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Background: Rapid and accurate detection of SARS-CoV-2 infection is the cornerstone of prompt patient care. However, the reliability of the antigen rapid diagnostic test (Ag-RDT) in the diagnosis of SARS-CoV-2 infection remains inconclusive., Methods: We conducted a field evaluation of Ag-RDT performance during the Shanghai Coronavirus disease 2019 (COVID-19) quarantine and screened 7225 individuals visiting our Emergency Department. 83 asymptomatic SARS-CoV-2 (+) individuals were enrolled in the current study. Simultaneously, Ag-RDT was performed to evaluate its testing performance., Results: For the Ag-RDT(-) cases, the average cycle threshold (Ct) values of the N gene were 27.26 ± 4.59, which were significantly higher than the Ct value (21.9 ± 4.73) of the Ag-RDT(+) individuals (p < 0.0001). The overall sensitivity of Ag-RDT versus that of RT-PCR was 43.37%. The Ag-RDT(+) individuals regarding the N gene's Ct value were 16 cases in the < 20 range, 12 in 20-25, 5 in 25-30, and 3 in 30-35. The corresponding sensitivity was 84.21%, 52.17%, 21.74% and 16.67%, respectively. Meanwhile, sampling had a straight specificity of 100% regardless of the Ct value., Conclusions: The Ag-RDT were extremely sensitive in asymptomatic COVID-19 individuals with a Ct value < 20., (© 2022. The Author(s).)

As the COVID-19 epidemic is still ongoing, a more rapid detection of SARS-CoV-2 infection such as viral antigen-detection needs to be evaluated for early diagnosis of COVID-19 disease. Here, we report the dynamic changes of SARS-CoV-2 viral antigens in nasopharyngeal swabs of COVID-19 patients and its association with the viral nucleic acid clearance and clinical outcomes. Eighty-five COVID-19 patients were enrolled for detection of SARS-CoV-2 viral antigens, including 57 anti-SARS-CoV-2 antibody negative cases and 28 antibody positive cases. The viral antigen could be detected in 52.63% (30/57) patients with SARS-CoV-2 antibody negative at the early stage of SARS-CoV-2 infection, especially in the first 5 days after disease onset (p = 0.0018) and disappeared in about 8 days after disease onset. Viral antigens were highly detectable in patients with low Ct value (less than 30) of SARS-CoV-2 nucleic acid RT-PCT assay, suggesting the expression of viral antigen was associated with high viral load. Furthermore, positive antigen detection indicated disease progression, nine cases with positive antigen (9/30, 30.0%), in contrast to two cases (2/27, 7.40%) (p = 0.0444) with negative antigen, which progressed into severe disease. Thus, the viral antigens were persistent in early stages of infection when virus was in highly replicating status, and viral antigen detection promises to rapidly screen positive patients in the early stage of SARS-CoV-2 infection.

Background: Viruses are the main infectious agents of acute respiratory infections in children. We aim to describe the epidemiological characteristics of viral pathogens of acute respiratory tract infections in outpatient children., Methods: From April 2018 to March 2019, the results of viral detection using oral pharyngeal swabs from 103,210 children with acute respiratory tract infection in the outpatient department of the Children's Hospital, Zhejiang University School of Medicine, were retrospectively analyzed. Viral antigens, including adenovirus (ADV), influenza A (FLUA), influenza B (FLUB) and respiratory syncytial virus (RSV), were detected by the colloidal gold method., Results: At least one virus was detected in 38,355 cases; the positivity rate was 37.2%. A total of 1910 cases of mixed infection with two or more viruses were detected, and the positivity rate of multiple infection was 1.9%. The ADV positivity rate was highest in the 3-6-year-old group (18.7%), the FLUA positivity rate was highest in the > 6-year-old group (21.6%), the FLUB positivity rate was highest in the > 6-year-old group (6.6%), and the RSV positivity rate was highest in the < 1-year-old group (10.6%). There was a significant difference in the positivity rate of viral infection among different age groups (χ 2  = 1280.7, P < 0.001). The rate of positive viral infection was highest in winter (47.1%). The ADV infection rate was highest in spring (18.2%). The rates of FLUA and FLUB positivity were highest in winter (28.8% and 3.6%, respectively). The rate of RSV positivity was highest in autumn (17.4%). The rate of positive viral infection in different seasons was significantly different (χ 2  = 6459.1, P < 0.001)., Conclusions: Viral infection rates in children differ for different ages and seasons. The positivity rate of ADV is highest in the preschool period and that of RSV is highest in infants; that of FLU increases with age. The total positive rate of viral infection in different seasons is highest in winter, as is the rate of FLU positivity.

Coronavirus disease-2019 (COVID-19), caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread globally since its first report and become a worldwide pandemic. In response to the outbreak of COVID-19, Center for Medical Device Evaluation, NMPA (CMDE) initiated emergency review and approval procedures to accelerate the process of reviewing emergent medical products and issued the Key Points of Technical Review for the Registration of SARS-CoV-2 Antigen/Antibody Tests (Key Points) to provide the requirements on the technical review of the tests. With uncontrolled spread and evolution of COVID-19 in the world, continuous prevention and measurements are necessary for fighting this pandemic and SARS-CoV-2 antigen/antibody tests are still urgently needed. This article is an attempt to expand clarification of the Key Points to wider audiences based on current understanding of SARS-CoV-2 to facilitate the development and application of SARS-CoV-2 antigen/antibody tests.

In this study, we isolated and identified 2 infectious bronchitis virus (IBV) strains from layer chickens soon after vaccination with the Massachusetts-Connecticut bivalent vaccine (Conn) and H120 and 4/91 booster vaccines in China in 2011. The results of cross-virus-neutralization tests and phylogenetic analysis of the S1 subunit of spike gene of these vaccine strains and other reference strains showed that strain LJL/110302 was of GI-19 lineage, whereas LLN/111169 was of the GI-1 lineage of the Conn serotype. Further comparative genomic analysis revealed that LLN/111169, an IBV strain with novel traits, originated from multiple recombination events (at least 3 recombination sites) between GI-19 and the Conn and 4/91 vaccine strains. LLN/111169 was pathogenic to specific pathogen-free (SPF) chickens. This is of prime importance because while IBV prevention measures worldwide are mainly dependent on modified live vaccine strains, our results showed that recombination between field and vaccine strains has produced a novel pathogenic IBV strain. In addition, LLN/111169 showed relatively broad tissue tropism (trachea, lungs, kidneys, and cecal tonsils) in infected SPF chickens. These results emphasize the importance of IBV surveillance in chicken flocks., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Porcine enteric alphacoronavirus (PEAV) was first discovered in China in February 2017, and the origin and virulence of this novel porcine coronavirus were not fully characterized. Here, we isolated a strain of PEAV, named GDS04 that is identified by immunofluorescence and typical crown-shaped particles observed with electron microscopy. Genomic analysis reveals that PEAV GDS04 shares a close relationship with SADS-CoV and SeACoV. Furthermore, newborn piglets orally challenged with PEAV GDS04 developed typical clinical symptoms as watery diarrhoea in neonatal piglets. Viral RNA was detected in faeces and various tissues of the infected piglets. Moreover, macroscopic and microscopic lesions in whole intestinal tract were observed, and viral antigen could be detected in the small intestines by immunohistochemical staining and electron microscopy. Importantly, the mortality rate of inoculated-newborn piglets was 100% and half of the cohabiting piglets died. Collectively, we demonstrate that PEAV is highly pathogenic in newborn piglets., (© 2018 Blackwell Verlag GmbH.)

Canine parvovirus (CPV) is an important pathogen in domestic dogs, and the original antigenic types CPV-2 and its variants, CPV-2a, 2b and 2c, are prevalent worldwide. A multiplex TaqMan real-time PCR method was developed for the detection and differentiation of four antigenic types of CPV. A set of primers and probes, CPV-305F/CPV-305R and CPV-2-305P (for CPV-2)/CPV-2a-305P (for CPV-2a, 2b and 2c), was able to differentiate CPV-2 and its variants (CPV-2a, 2b and 2c). Another set of primers and probes, CPV-426F/CPV-426R and CPV-2-426P (for CPV-2 and 2a)/CPV-2b-426P (for CPV-2b)/CPV-2c-426P (for CPV-2c), was able to differentiate CPV-2a (2), CPV-2b, and CPV-2c. With these primers and probes, the multiplex TaqMan real-time PCR assay detected effectively and differentiated CPV-2, 2a, 2b and 2c by two separate real-time PCRs. No cross reactivity was observed with canine distemper virus, canine adenovirus, and canine coronavirus. The detection limit of the assay is 10 1 genome copies/μL for CPV-2, CPV-2a, CPV-2b, and 10 2 copies/μL for CPV-2c. The multiplex real-time PCR has 100% agreement with DNA sequencing. We provide a sensitive assay that simultaneously detects and differentiate four antigenic types of CPV and the method was also used for quantification of CPVs viral genome., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Porcine rotavirus-A (PoRVA) is one of the common causes of mild to severe dehydrating diarrhea, leading to losses in weaning and postweaning piglets. A rapid, highly specific, and sensitive antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) was developed for detection of PoRVA, by using VP6 (a highly conserved and antigenic protein of group-A rotavirus)-directed rabbit polyclonal antibodies (capture antibody) and murine monoclonal antibodies (detector antibody). The detection limit of AC-ELISA was found to be equal to that of conventional reverse transcription-polymerase chain reaction (RT-PCR; about 10 2.5 TCID 50 /mL). For validation of the in-house AC-ELISA, 295 porcine fecal/diarrhea samples, collected from different provinces of China, were evaluated and compared with conventional RT-PCR and TaqMan RT-quantitative PCR (qPCR). The sensitivity and specificity of this in-house AC-ELISA relative to RT-qPCR were found to be 91.67% and 100%, respectively, with the strong agreement (kappa = 0.972) between these two techniques. Total detection rate with AC-ELISA, conventional RT-PCR, and RT-qPCR were found to be 11.2%, 11.5%, and 12.2%, respectively, without any statistical significant difference. Moreover, AC-ELISA failed to detect any cross-reactivity with porcine epidemic diarrhea virus, transmissible gastroenteritis virus, pseudorabies virus, and porcine circovirus-2. These results suggested that our developed method was rapid, highly specific, and sensitive, which may help in large-scale surveillance, timely detection, and preventive control of rotavirus infection in porcine farms.

An enzyme immunoassay (EIA) has been developed for hepatitis E virus (HEV) antigen (HEV-Ag) detection and marketed in China. This study aimed to evaluate the sensitivity of the assay and assess the value of HEV-Ag detection in the diagnosis of HEV infection in comparison with HEV RNA detection. Using serial dilutions of a genotype 4 HEV strain, significant correlation was found between the EIA (S/CO) and HEV RNA (IU/mL) concentration in the range 10(3.5) to 10(0.5) IU/mL HEV RNA, the Pearson correlation coefficient r approached 0.97. The EIA detection limit was 54.6 IU/mL, compared to 24 IU/mL for HEV RNA using real-time RT-PCR. In clinical samples from hepatitis E patients, the HEV-Ag and HEV RNA positivity rates were 55.6% (65/117) and 60.7% (71/117) in sera and 76.7% (56/73) and 84.9% (62/73) in stools, and the concordance of these two markers was 77.8% in sera and 80.8% in stools. In serum samples, the HEV-Ag positivity rate and the concordance between HEV-Ag and HEV RNA were inversely proportional to the presence of anti-HEV antibody. The presence of anti-HEV IgG could reduce the S/CO of the HEV-Ag EIA. These results reveal a significant correlation between the detection of HEV-Ag and HEV RNA. The sensitivity of the HEV-Ag EIA was lower than real-time RT-PCR but could be higher than conventional nested RT-PCR. Therefore, the detection of HEV-Ag in serum and faeces is valuable for the diagnosis and prognosis of HEV infection in developing regions where real-time RT-PCR is not available., (© 2015 John Wiley & Sons Ltd.)

In this study, a street rabies virus isolate, GXHXN, was obtained from the brain of one rabid cattle in Guangxi province of southern China. To characterize the biological properties of GXHXN, we first evaluated its pathogenicity using 4-week-old adult mice. GXHXN was highly pathogenic with a short incubation period and course of disease. Its LD50 of 10(-6.86)/mL is significantly higher than the LD50 of 10(-5.19)/mL of GXN119, a dog-derived rabies virus isolate. It also displayed a higher neurotropism index than the rRC-HL strain. However, the relative neurotropism index of GXHXN was slightly lower than that of GXN119. Analyzing antigenicity using anti-N and anti-G monoclonal antibodies (MAbs), all tested anti-N MAbs reacted similarly to GXHXN, CVS, and rRC-HL, but the reaction of anti-N MAbs to GXHXN was slightly different from GXN119. Moreover, 2/11 tested anti-G mAbs showed weaker reactivity to GXHXN than rRC-HL, whereas 4/11 showed stronger reactivity to GXHXN than CVS and GXN119, indicating that the structures of G might differ. In order to understand its genetic variation and evolution, the complete GXHXN genome sequence was determined and compared with the known 12 isolates from other mammals. A total of 42 nucleotide substitutions were found in the full-length genome, including 15 non-synonymous mutations. The G gene accounts for the highest nucleotide substitution rate of 0.70 % in ORF and an amino acid substitution rate of 0.95 %. Phylogenetic trees based on the complete genome sequence as well as the N and G gene sequences from 37 known rabies isolates from various mammals demonstrated that the GXHXN is closely related to the BJ2011E isolate from a horse in Beijing, the WH11 isolate from a donkey in Hubei, and isolates from dogs in the Fujian and Zhejiang provinces. These findings will be helpful in exploring the molecular mechanisms underlying interspecies transmission and the genetic variation of the rabies virus in different mammal species.

Background: Wild waterfowl are recognized as the natural reservoir for influenza A viruses. Two distinct lineages, the American and Eurasian lineages, have been identified in wild birds. Gene flow between the two lineages is limited. The H9N2 virus has become prevalent in poultry throughout Eurasia, and mainly circulates in wild ducks and shorebirds in North America., Methods: In this study, 22 H9N2 avian influenza viruses were isolated from wild waterfowl feces in East Dongting Lake Nature Reserve in November 2011 and March 2012. The phylogenetic, molecular, and antigenic characteristics of these viruses were analyzed based on analyses of the whole genome sequence of each isolate., Results: Phylogenetic analyses indicated that these H9N2 viruses were generated by reassortment events. The HA, NA, PA, and NS genes were derived from the American gene pool, and the other four genes were derived from the Eurasian gene pool. Antigenic analyses indicated that these viruses were significantly different from the Eurasian lineage viruses., Conclusions: This study presents the isolation of novel intercontinental recombinant H9N2 viruses from wild waterfowl in the East Dongting Lake wetland. The novel genotype H9N2 virus has not been detected in poultry in the region yet, and may be transmitted to naïve birds in poultry farms. Therefore, our results highlight the need for ongoing surveillance of wild birds and poultry in this region.

Background: Bovine viral diarrhea virus (BVDV) is a pathogen found worldwide in calves. It can cause significant economic losses in agriculture. Many BVDV strains have been isolated in China. However, the pathogenesis and complete gene characteristics of BVDV isolate have yet not been reported in China. Here, a BVDV isolate was isolated and its pathogenesis and complete genome were studied., Results: A new isolate of bovine viral diarrhea virus, named JL-1, was isolated from the spleen of a sick cow with diarrhea using MDBK cell culture. The complete genome of JL-1 is 12,276 nucleotides and contains a 5'-UTR of 382 nucleotides, a 3'-UTR of 188 nucleotides, and a large ORF encoding a polyprotein consisting of 3,901 amino acids. Genomic comparison and phylogenetic analyses of complete genomic sequence clearly showed that JL-1 fell into the BVDV-1b subtype. The result of pathogenesis of JL-1 strain showed that all infected calves developed clinical signs of elevated rectal temperatures, decreased leucopenia, and viral discharge. Viral antigen was detected in infected animal tissues using immunohistochemistry. Animals in the mock were normal. These results demonstrated that BVDV JL-1 was a virulent strain., Conclusions: This is the first study to report the pathogenesis and complete gene characterization of the BVDV strain in China. This report may set a good foundation for further study of BVDV in China.

Background: Outbreaks in poultry involving influenza virus from H7 subtype have resulted in human infections, thus causing a major concern for public health, as well as for the poultry industry. Currently, no efficient rapid test is available for large-scale detection of either antigen or antibody of H7 avian influenza viruses., Results: In the present study, a dual function ELISA was developed for the effective detection of antigen and antibody against H7 AIVs. The test was established based on antigen-capture-ELISA and epitope blocking ELISA. The two Mabs 62 and 98 which were exploited in the assay were identified to recognize two conformational neutralizing epitopes on H7 HA1. Both of the epitopes exist in all of the human H7 strains, including the recent H7N9 strain from China and > 96.6% of avian H7 strains. The dual ELISA was able to detect all of the five H7 antigens tested without any cross reaction to other influenza subtypes. The antigen detection limit was less than 1 HA unit of H7. For antibody detection, the sensitivity and specificity of the dual ELISA was evaluated and compared to HI and microneutralization using immunized animal sera to different H7 strains and different subtypes of AIVs. Results indicated that antibodies to H7 were readily detected in immunized animal sera by the dual ELISA whereas specimens with antibodies to other AIVs yielded negative results., Conclusions: This is the first dual-function ELISA reported for either antigen or antibody detection against H7 AIVs. The assay was highly sensitive and 100% specific in both functions rendering it effective for H7 diagnosis.

To investigate the epidemical characteristics and genotype distributions of bovine rotavirus (BRV) in China, 195 fecal samples were collected from calves with diarrhea in China. Fecal samples were detected for rotavirus A antigen using ELISA. The positive samples were screened for VP7 and VP4 by RT-PCR. G serotyping and P genotyping were conducted on 53 VP7 and VP4 positive samples using RT-PCR. The results showed that 82 samples were found positive for BRV. 752bp, 660bp and 285bp bands were amplified for G-typing. 478bp, 375bp and 361bp bands were amplified for P-typing. The G6 and G10 serotypes were 29 (54.7%) and 8 (15.1%) in positive samples for VP7. P[5] and P[11] genotypes were 28 (52.8%) and 10 (18.9%) in the positive samples for VP4. The main combinations of BRV G serotype and P genotype were G6P[5] (28.3%), G6P[5]P[11] (5.7%), G10P[5] (5.7%) and G10G6P[5] (5.7%), respectively. Other combinations (including untypable) of G serotype and P genotype were 54.6%. The dominant G serotype and P genotype were G6 and P[5] respectively. The predominant combination of G and P serotypes was G6P[5]. This has significance for establishing the preventive measures against diarrhea caused by group A rotaviruses in cattle., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: Three influenza pandemics outbroke in the last century accompanied the viral antigen shift and drift, resulting in the change of antigenic property and the low cross protective ability of the existed antibody to the newly emerged pandemic virus, and eventually the death of millions of people. The antigenic characterizations of the viruses isolated in central China in 2004 and 2006-2007 were investigated in the present study., Results: Hemagglutinin inhibition assay and neutralization assay displayed differential antigenic characteristics of the viruses isolated in central China in two periods (2004 and 2006-2007). HA genes of the viruses mainly located in two branches in phylogeny analysis. 53 mutations of the deduced amino acids of the HA genes were divided into 4 patterns. Mutations in pattern 2 and 3 showed the main difference between viruses isolated in 2004 and 2006-2007. Meanwhile, most amino acids in pattern 2 and 3 located in the globular head of the HA protein, and some of the mutations evenly distributed at the epitope sites., Conclusions: The study demonstrated that a major antigenic drift had occurred in the viruses isolated in central China. And monitoring the antigenic property should be the priority in preventing the potential pandemic of H5N1 avian influenza virus.

Domestic ducks in southern China act as an important reservoir for influenza viruses and have also facilitated the establishment of multiple H6 influenza virus lineages. To understand the continuing evolution of these established lineages, 297 H6 viruses isolated from domestic ducks during 2006 and 2007 were genetically and antigenically analyzed. Phylogenetic analyses showed that group II duck H6 viruses had replaced the previously predominant group I lineage and extended their geographic distribution from coastal to inland regions. Group II H6 virus showed that the genesis and development of multiple types of deletions in the neuraminidase (NA) stalk region could occur in the influenza viruses from domestic ducks. A gradual replacement of the N2 NA subtype with N6 was observed. Significant antigenic changes occurred within group II H6 viruses so that they became antigenically distinguishable from group I and gene pool viruses. Gene exchange between group II H6 viruses and the established H5N1, H9N2, or H6N1 virus lineages in poultry in the region was very limited. These findings suggest that domestic ducks can facilitate significant genetic and antigenic changes in viruses established in this host and highlight gaps in our knowledge of influenza virus ecology and even the evolutionary behavior of this virus family in its aquatic avian reservoirs.

Enterovirus 71 (EV71) is a highly infectious agent that causes hand-foot-mouth disease (HFMD) in humans. Effective vaccination against EV71 infection is critically important, given the recent outbreak of HFMD in the Asia-Pacific region, where it has shown significant mortality and morbidity. There is currently no approved anti-viral therapy available to treat the disease. While several vaccine manufacturers are actively developing EV71 vaccines, there are no international reference standards available to conduct quality control on EV71 vaccines or to assess the effectiveness of EV71 vaccines in immunized populations. In the current report, antigen reference standard based on the C4 subtype of the EV71 vaccine strain was developed. In addition, neutralizing antibody (NTAb) reference panels were analyzed and standards with various neutralizing titers were selected. These reference antigens were used to calibrate vaccine samples from several producers and found that five EV71 antigens and the national reference standards showed good linearity and parallelism. Moreover, mice immunized with various vaccines at doses standardized by these national references showed comparable NTAb responses. Finally, the national NTAb reference panels were found to effectively reduce assay discrepancy between different labs. Taken together, these national reference standards are highly valuable for the standardization and evaluation of EV71 vaccines., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Nasopharyngeal carcinoma (NPC) has remarkable epidemiological features, including regional, racial, and familial aggregations. The aim of this review is to describe the epidemiological characteristics of NPC and to propose possible causes for the high incidence patterns in southern China. Since the etiology of NPC is not completely understood, approaches to primary prevention of NPC remain under consideration. This situation highlights the need to conduct secondary prevention, including improving rates of early detection, early diagnosis, and early treatment in NPC patients. Since the 1970's, high-risk populations in southern China have been screened extensively for early detection of NPC using anti-Epstein-Barr virus (EBV) serum biomarkers. This review summarizes several large screening studies that have been conducted in the high-incidence areas of China. Screening markers, high-risk age range for screening, time intervals for blood re-examination, and the effectiveness of these screening studies will be discussed. Conduction of prospective randomized controlled screening trials in southern China can be expected to maximize the cost-effectiveness of early NPC detection screening.

Routine surveillance for porcine reproductive and respiratory syndrome virus (PRRSV) infections is crucial for the epidemiological control of this disease. Antibody tests are widely used but cannot differentiate between vaccination and reinfection. We developed a PRRSV antigen capture enzyme-linked immunosorbent assay (ELISA) using well-characterized monoclonal antibodies (MAbs) raised against the nucleocapsid (N) protein of North American and European PRRSV. This antigen assay detected purified N protein from both genotypes at levels as low as 0.4 and 0.8 ng, respectively. The specificity and sensitivity of the N antigen assay were evaluated with ground lung tissues from 8 PRRSV-infected and 16 healthy swine, and culture supernatants from six PRRSV isolates as well as other swine viruses were confirmed by reverse transcriptase PCR (RT-PCR). Antigen assays were positive in all eight infected tissues and with six different PRRSV isolates, with no false positives among healthy tissues and other swine viruses (i.e., pseudorabies and foot and mouth disease viruses). A number of sera, field collected from 466 vaccinated and asymptomatic pigs in Guangdong, China, between 2008 and 2009, tested positive by the N antigen assay (12.45%), RT-PCR (15.02%), and a commercial test for antibodies against PRRSV (78.97%). Of the 466 sera, 47 were positive by both antigen and RT-PCR tests, 11 by antigen test only, and 23 by RT-PCR only; the two assays had an overall agreement of 92.7%, indicating a significant percentage of active PRRSV in asymptomatic pigs despite previous immunization. These findings suggest that the antigen assay is a valuable field tool for the epidemiological control of PRRSV that can be used for rapid screening, particularly in asymptomatic animals.

During swine influenza surveillance from 2007 to 2008, 10 H1N1 viruses were isolated and analyzed for their antigenic and phylogenetic properties. Our study revealed the emergence of avian-origin European H1N1 swine influenza virus in China, which highlights the necessity of swine influenza surveillance for potential pandemic preparedness.

Surveys were carried out in 2003-2006 to better understand the epidemiology of hantaviruses in the Inner Mongolia Autonomous Region of China (Inner Mongolia). Hemorrhagic fever with renal syndrome (HFRS) was first reported in this region in 1955 and has been an important public health problem here since then. During 1955-2006, 8,309 persons with HFRS were reported in Inner Mongolia (average incidence rate 0.89/100,000), and 261 (3.14%) died. Before the 1990s, all HFRS cases occurred in northeastern Inner Mongolia. Subsequently, HFRS cases were registered in central (1995) and western (1999) Inner Mongolia. In this study, hantaviral antigens were identified in striped field mice (Apodemus agrarius) from northeastern Inner Mongolia and in Norway rats (Rattus norvegicus) from middle and western Inner Mongolia. Phylogenetic analysis of hantaviral genome sequences suggests that HFRS has been caused mainly by Hantaan virus in northeastern Inner Mongolia and by Seoul virus in central and western Inner Mongolia.

Objective: To understand the prevalence of rabies among wild animals and the animal species in rabies epidemic areas of Zhejiang province., Methods: One hundred and sixty samples were collected from the brain tissues of cats, stoats, Apodemus agrarius, Moschus chinensis, and Sus scrofa in Lishui and Chunan cities of Zhejiang province. Each sample was divided into four parts: cerebrum, mesencephali, cerebellum and gyms hippocampi which were used to determine the positive samples by detection of rabies virus specific antigens and nucleotides, using DFA and RT-PCR methods., Results: Positive slides in the tests contained a glaring, apple green brilliance fluorescence using rabies virus specific monoclonal antibody against nucleoprotein. Using Nested-PCR method targeted at part of N gene, five positive samples were identified which consisting of four positive samples from stoats with positive ratio as 8.33% (4/48) and one positive sample from Apodemus agrarius with positive ratio as 1.75% (1/57). However, no positive result was found from cats, Moschus chinensis, and Sus scrofa samples., Conclusion: Rabies virus positive samples were identified from stoats and Apodemus agrarius in the mountain areas, with biological diversity in Lishui and Chunan cities of Zhejiang province, indicating that stoats and Apodemus agrarius might have played a role in human rabies and acted as host of rabies virus. In order to effectively prevent and control rabies virus under these complicated geographical and ecological environment, we must understand and evaluate the infection situation among animals in these regions.

Objective: To isolate hantavirus from Lishui county--one of the epidemic regions for hemorrhagic fever with renal syndrome (HFRS), in Zhejiang province, and to identify the serotype and molecular/biological characteristics of a new HTN subtype hantavirus (HV) strains, hopefully to provide evidence for HFRS prevention and therapy., Methods: Data on the host animals was collected from Lishui, Zhejiang province in 2007. Direct immunofluorscece assay was adopted to determine HFRS antigens and the lung tissues from HV infected Vero-E6 cells for HV isolation, then total RNA was extracted from Hantavirus Lishui strains and amplified by RT-PCR M, S segments of strains genome were also cloned and sequenced and compared with those of other strains of HV., Results: 2 strains virus (ZLS6-11 and ZLS-12) were successfully isolated from 7 positive lung samples of mice and were identified as HTNV by anti-McAb and phylogenetic analysis. With sequence compation,we found that 2 strains with complete M and S segment had higher homology with HTN-type strains than with other types of HV, but 13.4%-20.7% and 10.3%-16.1% of the genes were found which were different from HTNV. The phylogenetic trees constructed by complete S and M segment showed that ZLS6-11 and ZLS-12 strains were located in HTNV group,and structured independent embranchment., Conclusion: ZLS6-11 and ZLS-12 Strains were believed to belong to HTN-type and phylogenetically different from the HTNV.

Background: Very little is known about human rotaviruses in the northwest of China. To investigate the genomic diversity, we evaluated the distribution of rotavirus genotypes in this region covering a 10-year period (1996-2005)., Methods: Rotavirus antigen was detected in stool specimens by enzyme immunoassay (EIA), and G and P genotyping was performed by reverse transcription-polymerase chain reaction and nucleotide sequencing methods., Results: A total of 783 stool specimens collected from children with diarrhea, under 5 years of age, attending an urban hospital in Xinjiang were tested for rotavirus antigen, and 398 (50.8%) were positive. Overall, the most prevalent rotavirus genotype was G1P[8] (40.0%), followed by G3P[8] (17.5%), G2P[4] (8.3%), and G2P[6] (6.5%). G1 rotavirus was the most prevalent genotype until 2004. However, in 2005, G3 rotavirus (51.9%) became a dominating strain. Only one G9 strain was isolated in this region (isolated for the first time in 1999) and it became a more prevalent strain (21.2%) in 2005., Conclusions: The results of this study are of importance to the decision makers in the evaluation of rotavirus vaccines in China.

To investigate whether healthy animals are potential carriers of rabies virus in China, 153 domestic dogs were collected from a rabies enzootic area, Anlong county in Guizhou Province, and monitored for 6 months. Initially, findings of rabies virus antigen in the saliva of 15 dogs by an enzyme-linked immunosorbent assay (ELISA) test suggested they might be carriers. These 15 dogs were kept under observation for 6 months. None of the dogs showed any clinical signs of rabies during the observation period. Moreover, using the ELISA test alone, detection of rabies virus antigen in saliva of some animals was not consistent during the observation period. However, none of the saliva samples collected either at the time of acquisition or during the observation period was found to be positive for rabies virus RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). Furthermore, neither viral antigen nor viral RNA was detected in the brain samples collected at the time of euthanasia. These results do not provide support for the contention that healthy dogs act as carriers in rabies. Caution is urged when preliminary and nondefinitive tests, such as ELISA, are used to infer clinical status related to rabies.

Objective: To investigate hepatitis E virus (HEV) infection among pigs in Henan province., Methods: A total of 623 swine sera, collected from 5 districts, were divided into two groups, under 3-month of age and over 3-month of age. They were tested for HEV antigen and antibody by using ELISAs, respectively. The sera positive for HEV antigen were tested for HEV RNA with RT-PCR. The positive products of RT-PCR were cloned and sequenced., Results: The positive rates of anti-HEV antibody of the groups under 3-month and over 3-month of age were 90.27% and 92.55%, respectively, without statistical difference, while those of HEV antigen were 15.93% and 5.69%, respectively, with significant difference. The positive rates of anti-HEV antibody and HEV antigen were significantly different among different districts. HEV RNA was detectable in 5 of 47 HEV antigen positive samples. The sequence analysis showed that in 4 of 5 specimens the sequence belonged to genotype 4 while in the remaining one the sequence was genotype 1., Conclusion: The prevalence rate of HEV infection in pigs was high in Henan province and the rate differed in different districts.

Objective: To investigate clinical features of childhood Weber-Christian disease (WCD) and the relationship between WCD and virus., Methods: The clinical characteristics, laboratory findings, therapy and clinical course of nine patients were reviewed and the viral antigens (EBV, CMV, HSV1 and HSV2) were detected., Results: They were six males and three females with a median age of 9 years. They included four simple and five systemic WCD, and all presented fever and tender subcutaneous nodules. Other clinical features included hepatomegaly in nine patients, splenomegaly in two, lymphadenhypertrophy in six, respiratory system involved in two, gastrointestinal tract involved in two and convulsion and bleeding in one. Anaemia was noted in seven patients, raised ALT in three, hypergammaglobulnaemia in three, proteinuria in one and three of six patients positive of antinuclear antibodies (ANA). No viral antigens were found. Corticosteroids therapy was administrated for all patients, immunoglobulin for two, non-steroidal anti-inflammatory agents for three and cyclophosphamide for one. Five patients released after therapy and three patients died., Conclusions: WCD is a severe disease characterized by relapsing, febrile subcutaneous nodules and biopsy is needed for early diagnosis. The viral infection may not be associated with WCD.

H9N2 influenza viruses have become established in terrestrial poultry in different Asian countries over the last 2 decades. Our previous study demonstrated that quail harbor increasingly diverse novel H9N2 reassortants, including both Chicken/Beijing/1/94 (Ck/Bei-like) and Quail/Hong Kong/G1/97 (G1-like) viruses. However, since 1999, the genesis and evolution of H9N2 viruses in different types of poultry have not been investigated systematically. In the present study, H9N2 viruses isolated from chickens, ducks, and other minor poultry species were characterized genetically and antigenically. Our findings demonstrate that Ck/Bei-like H9N2 viruses have been introduced into many different types of poultry in southern China, including quail, partridges, chukar, pheasant, guinea fowl, and domestic ducks, while G1-like viruses were commonly detected in quail, less frequently detected in other minor poultry species, and not detected in chickens and ducks. Genetic analysis revealed 35 genotypes of H9N2 viruses, including 14 novel genotypes that have not been recognized before. Our results also suggested that two-way interspecies transmission exists between different types of poultry. Our study demonstrates that the long-term cocirculation of multiple virus lineages (e.g., H5N1 and H9N2 viruses) in different types of poultry has facilitated the frequent reassortment events that are mostly responsible for the current great genetic diversity in H9N2 and H5N1 influenza viruses in this region. This situation favors the emergence of influenza viruses with pandemic potential.

An H6N1 virus, A/teal/Hong Kong/W312/97 (W312), was isolated during the "bird flu" incident in Hong Kong in 1997. Genetic analysis suggested that this virus might be the progenitor of the A/Hong Kong/156/97 (HK/97) H5N1 virus, as seven of eight gene segments of those viruses had a common source. Continuing surveillance in Hong Kong showed that a W312-like virus was prevalent in quail and pheasants in 1999; however, the further development of H6N1 viruses has not been investigated since 2001. Here we report influenza virus surveillance data collected in southern China from 2000 to 2005 that show that H6N1 viruses have become established and endemic in minor poultry species and replicate mainly in the respiratory tract. Phylogenetic analysis indicated that all H6N1 isolates had W312-like hemagglutinin and neuraminidase genes. However, reassortment of internal genes between different subtype virus lineages, including H5N1, H9N2, and other avian viruses, generated multiple novel H6N1 genotypes in different types of poultry. These novel H6N1/N2 viruses are double, triple, or even quadruple reassortants. Reassortment between a W312-like H6N1 virus and an A/quail/Hong Kong/G1/97 (HK/97)-like H9N2 virus simultaneously generated novel H6N2 subtype viruses that were persistent in poultry. Molecular analyses suggest that W312-like viruses may not be the precursors of HK/97 virus but reassortants from an HK/97-like virus and another unidentified H6 subtype virus. These results provide further evidence of the pivotal role of the live poultry market system of southern China in generating increased genetic diversity in influenza viruses in this region.

Background: Highly pathogenic avian influenza H5N1 virus has caused increasing human infection in Eurasia since 2004. So far, H5N1 human infection has been associated with over 50% mortality that is partly because of delay of diagnosis and treatment., Objectives and Methods: Here, we report that an H5N1 influenza virus infected a 31-year-old patient in Shenzhen in June 2006. To identify the possible source of the infection, the human isolate and other H5N1 influenza viruses obtained from poultry and wild birds in southern China during the same period of time were characterized., Results: Genetic and antigenic analyses revealed that the human H5N1 influenza virus, Shenzhen/406H/06, is of purely avian origin and is most closely related to viruses detected in poultry and wild birds in Hong Kong in early 2006., Conclusions: The findings of the present study suggest that the continued endemicity of H5N1 influenza virus in the poultry in southern China increases the chance for introduction of the virus to humans. This highlights the importance of continued surveillance of poultry and wild birds for determining the source for human H5N1 infection.

To provide a better understanding of hantavirus epidemiology in China, Korean field mice (Apodemus peninsulae) and striped field mice (Apodemus agrarius) were captured in Jilin province, China, where haemorrhagic fever with renal syndrome (HFRS) is endemic. Hantavirus antigens were detected in eight of the 130 A. peninsulae individuals and in four of the 193 A. agrarius individuals by using an immunofluorescence assay. Partial S and M segments were amplified from all of the antigen-positive samples. Furthermore, two hantaviruses (CJAp89 and CJAp93) were isolated successfully in cell culture and the entire S and M segments were amplified from one of them (CJAp93). Phylogenetic analysis of these sequences (partial or complete) showed that hantaviruses carried by A. peninsulae and A. agrarius form two distinct lineages, although viruses carried by A. peninsulae are similar to those isolated previously from A. agrarius in China and from HFRS patients in Russia. However, the viruses detected in A. peninsulae in China are genetically different from those detected in A. peninsulae in other countries. These data suggest that A. peninsulae is also a natural host for HTNV in north-eastern China.

Objective: To identify the etiological agent of acute gastroenteritis outbreaks occurred in 6 hospitals in Beijing from November to the end of 2006 and to characterize the virus on molecular biology., Methods: Rota-strip was used to detect rotavirus antigen and PAGE for rotavirus RNA in stool specimens collected from patients with gastroenteritis at the first stage. Reverse transcription-polymerase chain reaction(RT-PCR) was performed to detect Norovirus in stool specimens. Full length of Norovirus VP1 genes were amplified from Norovirus positive samples by RT-PCR and sequenced after the gene was cloned into vector pUCm-T. The sequences of partial VP1 gene at the 5' end of full-length gene were obtained from 2 of the Norovirus positive samples to analyze the relationship of these viruses at molecular level., Results: Norovirus was detected in 17 of the 30 stool specimens with an overall positive rate of 56.7%. Positive rates were all above 42.9% in specimens collected from each of the hospital. Sequence analysis on one of the full-length of VP1 amplified by RT-PCR from one of the positive specimens NV8-Beijing indicated that it belonged to G II-4 genotype. This strain shared 94.8% and 95.2% identities over the complete major capsid gene to Lanzhou strain form Lanzhou China and Farmington Hill strain from USA which belonged to G II-4 genotype, but only 91.1% identity to the CR2905 from Beijing China identified from specimen collected in late 2004. The sequences of 5' end of VP1 genes amplified from other two samples collected from different hospitals showed only one nucleotide mutation compared to NV8-Beijing in the correspondence part, indicating that these two strains also belonged to G II-4 genotype., Conclusion: Norovirus was the etiological agent causing outbreaks of acute gastroenteritis in hospitals in Beijing and the strain with G II-4 genotype which was closer to the Lanzhou and Farmington strains than Beijing strains identified in 2004.

Objective: To study the differences between epidemic strains of influenza virus subtype A3 circulated in China and Occident in past 18 years, in genetic level, and vaccine strains recommended by WHO in corresponding time., Methods: Amino acid sequences of HA1 regions of the epidemic strains, which circulated in China and Occident from 1988 to 2005, and the vaccine strains of influenza virus subtype A3 were compared by BioEdit and analyzed on the differences of HA1 and it's antigen determinants, Results: Differences between epidemic strains and vaccine strains recommended in corresponding year, both in HA1 and it' s antigen determinant regions, were obviously greater than that between epidemic strains and vaccine strains recommended in next round (P< 0.01). However, differences between epidemic strains in Occident and vaccine strains recommended in corresponding year were slightly greater than that between epidemic strains and vaccine strains recommended in next round and it was not marked (P >0.05). In addition, differences between epidemic strains and vaccine strains which being used for several years, whether in China or in Occident, constantly increased accompanying the used time prolonged., Conclusion: There was an obvious lag between vaccine strains recommended by WHO, analyzed in genetic level, and epidemic strains of influenza virus subtype A3 circulated in China.

Thirty-three tobacco samples showing typical symptoms of Potato virus Y (PVY) infection were obtained from tobacco fields in various regions of China. The results of indirect ELISA confirmed the infection with PVY. All the isolates had a capacity to infect tobacco systemically in greenhouse, causing either of two main symptoms: veinal necrosis and mosaic. The nucleotide and amino acid sequences of the coat protein (CP) gene and protein, respectively, of the isolates were determined. Comparison of the isolates revealed a high conservation of the CP gene with an identity of 83.2%. A phylogenetic tree of 41 Chinese isolates of PVY, based on complete CP gene, showed 3 groups corresponding to the strains PVYNTN (A group), PVYO (C group) and a putative new strain similar to PVYN (B group). The amino acid sequences of complete CP protein of the isolates showed an identity of 87.6%. The highest identity was observed in the C-terminal half of the CP protein, where only 11 amino acid differences could be observed, in contrast to the N-terminal half with 22 differences.

The importance of diseases of tomato caused by begomoviruses is increasing worldwide. Here, we report that several begomoviruses are associated with tomato leaf curl disease in Yunnan province, China. 14 tomato samples showing leaf curl symptoms were collected in three districts in Yunnan, and they fell into four groups according to their reaction with a panel of 16 monoclonal antibodies in TAS-ELISA. Comparison of partial DNA-A sequences amplified with degenerate primers confirmed the existence of several types of begomoviruses. The complete DNA-A sequences of 4 isolates (Y25, Y41, Y72, Y161), corresponding to the four groups, were determined. Sequence comparisons and phylogenetic analysis revealed that they corresponded to four previously identified begomoviruses. Groups I, II and IV are most closely related to Tomato yellow leaf curl China virus (TYLCCNV), Tobacco curly shoot virus (TbCSV) and Tobacco leaf curl Yunnan virus (TbLCYNV), respectively, while Group III shows close relationships with Tomato yellow leaf curl Thailand virus (TYLCTHV). In addition, all isolates in Groups I and III were found to be associated with DNAbeta molecules, while satellite DNA was not found in virus isolates in Groups II and IV. The complete DNAbeta sequences of three isolates from Group III (Y72, Y77, Y79) were determined. Sequence analysis showed that Y72beta, Y77beta and Y79beta seem to be different from other characterised DNAbeta, sharing the highest nucleotide sequence identity with DNAbeta of TbCSV.

Objective: To study the susceptibility of Aedes albopictus to dengue virus infection., Methods: Aedes albopictus from 15 collections in Guizhou province were challenged orally with dengue virus 1-4 types, respectively. The total RNA from mosquitos were extracted. The viral NS1 gene fragment was amplified with reverse transcriptase polymerase chain reaction (RT-PCR). Dengue virus in mosquitoes was isolated with C6/36 cells. Then the viral antigen was detected by indirect immunofluorescence assay (IFA). Antigen and nucleic acid of dengue virus from 15 geographic strains of Aedes albopictus orally infected with dengue viruses (DEN-1, DEN-2, DEN-3 and DEN-4) were detected by IFA, RT-PCR and the virus was isolated with C6/36 cells, respectively., Results: The rates of Aedes albopictus orally infected with DEN-1, DEN-2, DEN-3 and DEN-4 were 12/15, 12/15, 8/15 and 13/15, respectively., Conclusions: Different geographic strains of Aedes albopitus in Guizhou were susceptible to dengue viruses.

Mortality from myeloid leukosis was observed in commercial layers from 12 farms in northern China. Affected chickens were extremely thin and dehydrated, bleeding occurred in feather follicles and claws, combs were pale and anaemic, phalanges were swollen, and many yellowish-white tumours were seen on the visceral surface of the sternum. Focal tumour cells, with spherical eosinophilic granules in the cytoplasm, were found in the liver, spleen, kidney, ovary, oviduct, lung, bone marrow, proventriculus and gut by histopathological examination. Immunohistochemical studies with a monoclonal antibody to gp85 of avian leukosis virus subgroup J (ALV-J) revealed antigen in all organs examined. Polymerase chain reaction tests using a pair of ALV-J-specific primers H5/H7 (Smith et al., 1998) produced a 545 basepair fragment. The sequence of the Polymerase chain reaction product was compared with that of the ALV-J HPRS-103 prototype strain. The identity of nucleotides and predicted amino acids was 97.4% and 96.1%, respectively. On this basis the disease in the egg-type chickens was diagnosed as an ALV-J infection. This is the first report of field cases of myeloid leukosis caused by ALV-J in commercial egg-type chickens.

Hantavirus HV114, isolated from urine of a patient during epidemic of hemorrhagic fever with renal syndrome (HFRS) in China, was subjected to a detailed serological characterization using enzyme-linked immunosorbent assay (ELISA), neutralization test and indirect immunofluorescence antibody assay (IFA). It has been found that HV114 is antigenically similar to the hantavirus A9 strain isolated in China and to the Hantaan 76-118 virus (HTNV 76-118), but different from the hantaviruses isolated from Apodemus agrarius in the region endemic for HFRS.

The H5N1 influenza virus, which killed humans and poultry in 1997, was a reassortant that possibly arose in one type of domestic poultry present in the live-poultry markets of Hong Kong. Given that all the precursors of H5N1/97 are still circulating in poultry in southern China, the reassortment event that generated H5N1 could be repeated. Because A/goose/Guangdong/1/96-like (H5N1; Go/Gd) viruses are the proposed donors of the hemagglutinin gene of the H5N1 virus, we investigated the continued circulation, host range, and transmissibility of Go/Gd-like viruses in poultry. The Go/Gd-like viruses caused weight loss and death in some mice inoculated with high virus doses. Transmission of Go/Gd-like H5N1 viruses to geese by contact with infected geese resulted in infection of all birds but limited signs of overt disease. In contrast, oral inoculation with high doses of Go/Gd-like viruses resulted in the deaths of up to 50% of infected geese. Transmission from infected geese to chickens occurred only by fecal contact, whereas transmission to quail occurred by either aerosol or fecal spread. This difference is probably explained by the higher susceptibility of quail to Go/Gd-like virus. The high degree of susceptibility of quail to Go/Gd (H5N1)-like viruses and the continued circulation of H6N1 and H9N2 viruses in quail support the hypothesis that quail were the host of origin of the H5N1/97 virus. The ease of transmission of Go/Gd (H5N1)-like viruses to land-based birds, especially quail, supports the wisdom of separating aquatic and land-based poultry in the markets in Hong Kong and the need for continued surveillance in the field and live-bird markets in which different types of poultry are in contact with one another.

Immunoperoxidase histochemical assay with monoclonal antibody against human cytomaglovirus (HCMV) was used to detect immediate early antigen (IEA) and early antigen (EA) of HCMV infection in liver tissue of 72 pediatric cases (34 autopsies and 38 biopsies). The HCMV antigen was positive in 25% (18/27). Among them, 12 cases were both HCMV-IEA and EA positive; 4 were HCMV-IEA positive and 2 HCMV-EA positive only. Liver HCMV infection rate in neonates, the infants with the age < 1 year and > 1 year was 8.0%, 60.0%, and 14.8%, respectively, indicating that liver HCMV infection occurred at various ages. The liver HCMV infection rate in different diseases was 50.0% in infantile hepatitis syndrome; 70.0% in extrabiliary malformation, and 12.5% in other hepatopathies, suggesting that infantile hepatitis syndrome and extrabiliary malformation were related with HCMV infection in liver tissues.

Apodemus agrarius was trapped in the fields and Rattus norvegicus was trapped within the houses in the villages of Jiande County, a region in the Zhejiang Province of China endemic for hemorrhagic fever with renal syndrome (HFRS). Antibodies to hantaviruses were detected in three (16.7%) of 18 A. agrarius and 12 (13.5%) of 89 R. norvegicus, whereas hantavirus antigens were detected in the lung tissues of four (22.2%) of 18 and nine (10.1%) of 89 of these rodents, respectively. Three hantaviruses, one from A. agrarius and two from R. norvegicus, were isolated and found to be antigenically similar to Hantaan and Seoul serotype viruses, respectively. A serologic study of 437 clinically defined HFRS patients conducted in Jiande County in 1988 revealed that the ratio of Hantaan (72.5%) to Seoul (26.8%) serotype virus infections was 2.7:1. Two epidemic seasons were found, with a major peak in November and a minor peak in June, and both were associated with Hantaan serotype virus infections that coincided with two seasonal peaks of the A. agrarius population and local agricultural activities in the fields. Seoul serotype virus infections occurred with a small peak during the months of December through May, in which in-house activities were dominant. All data suggested that Jiande County was an area endemic for HFRS, predominantly of the Hantaan virus serotype, combined with Seoul serotype virus infections.

Forty-two cases of Chinese T-cell lymphoma were studied for expression of Epstein-Barr virus (EBV) encoded RNA (EBER-1) and EBV latent membrane protein-1 (LMP-1) using in situ hybridization and immunohistochemistry, respectively. EBV was detected in tumour cells in 24/39 peripheral T-cell lymphomas (62%), comprising 18/27 pleomorphic, medium and large cell lymphomas (67%), 4/6 angioimmunoblastic lymphadenopathy-like lymphomas (67%), 2/2 Lennert's lymphomas, 0/2 anaplastic large cell lymphomas, and 0/2 T-zone lymphomas. EBV was not found in three T-lymphoblastic lymphomas. EBV was associated with 12/24 nodal (50%) compared with 12/15 extranodal (80%) peripheral T-cell lymphomas. In EBV positive nodal lymphomas, 9/12 cases (75%) contained less than 10% EBER positive tumour cells. In EBV positive extranodal lymphomas, 9/11 cases (82%) showed EBV gene expression in more than 50% of the tumour cells, and in five of these almost all tumour cells were positive. Lymphomas of the nasopharynx (mainly midline granuloma-type) showed EBER-1 expression in nearly all tumour cells. LMP-1 was detected in 19/23 EBER positive peripheral T-cell lymphomas (83%). Our results show that EBV is strongly associated with peripheral T-cell lymphomas in Chinese. An important role for the virus is suggested in lymphomas of the nasopharynx. The significance of EBV in T-cell lymphomas that contain only a minor population of virally infected tumour cells is currently unclear.

Genital herpes is one of 8 legally reportable sexually transmitted diseases (STD) in China. Using a HSV antigen ELISA kit we detected and typed HSV antigen in 1,148 clinical specimens collected from the genital organs (penis, cervix, vagina and vulva) of 446 men and 702 women in Qindao and divided into 11 different professional and 2 special groups (patients with cervical cancer and pregnant women). The highest positive rate of HSV antigen was found among long-distance transport drivers (48.0%). The second and third high positive rates were among waiters and waitresses in private, restaurants (39.2%) and patients with cervical cancer (38.2%). The positive rates among self-employed retailers and employees in private inns and restaurants were notably higher than those among employees in state-run shops, restaurants and hotels. And, the positive rate among workers was higher than that among peasants. There was no notable difference between the positive rate of HSV antigen among men (24.2%) and that among women (21.5%). But the incidence of HSV-2 infection was much higher than that of HSV-1 infection. The results indicate that some special professional groups have high rates of genital HSV infection. More attention needs to be paid to these special groups in order to control sexually transmitted herpes diseases.

It has been known for some time that the Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC). The tumor cells are known to harbor EBV in a latent state. Latently-infected B cells that have become growth transformed by EBV in vitro express some 10 antigens, two of which (Epstein-Barr nuclear antigen 2 [EBNA2] and the latent membrane protein [LMP]) are associated with cellular transformation. We evaluated the expression of these two EBV antigens in NPC by probing tissue sections with monoclonal antibodies. We found that EBNA2 was not expressed and that LMP was expressed in seven of nine biopsy specimens. It is therefore postulated that either there are subsets of NPC or that LMP may be involved only in certain stages of tumor formation.

Eight strains of rotaviruses isolated from diarrheal animals (4 from calves and 4 from piglets) in China were compared by serotyping with reference animal rotavirus strains (bovine NCDV, porcine OSU and simian SA-11 and human rotavirus Wa strain). Two-way cross neutralization test showed no antigenic difference between all 4 local strains of bovine rotavirus (BRV007, BRV014, HN-7 and BRV6555) and reference NCDV, so they belonged to rotavirus serotype 6 (bovine rotavirus serotype 1 or NCDV-serotype). Meanwhile, the four strains of Chinese porcine rotavirus could be determined into 2 different serotypes. One (Li99) was neutralised to a high titer with the antiserum against reference OSU virus and probably related to OSU (serotype 5 or porcine serotype 1). The other three strains (Lin71, Nan86 and Jiang150) were antigenically obviously different from Li99 and did not react with the antiserum against OSU. They were tentatively considered as porcine rotavirus serotype 2. All the strains of bovine and porcine rotavirus did not cross-neutralise with simian SA-11 and human Wa strain. There was also no antigenic relationship between bovine rotaviruses and porcine rotaviruses.

A serological study was undertaken to determine the role of arboviruses as etiological agents of encephalitis in the People's Republic of China (PRC). Paired sera were collected during mosquito seasons in 1988-1990 from 614 patients with possible viral encephalitis in 15 regions of PRC and tested for haemagglutination inhibiting antibodies to selected arboviruses. Seroconversions were documented to alphavirus and flavivirus antigens in 13.0 and 18.7% of patients respectively in most of the study areas. No California group seroconversion was detected. The age of alphavirus seroconvertors ranged from 2 months to 32 years and of flavivirus seroconvertors from 6 months to 50 years, with higher numbers in males. Serious central nervous system manifestations were seen more commonly in flavivirus seroconvertors. This study affirms the importance of flavivirus as causative agents of encephalitis in PRC and provides evidence that one or more alphaviruses are causing symptomatic infections with neurological involvement in PRC.

Reassortant influenza A viruses bearing H1 haemagglutinin and N2 neuraminidase were isolated from humans in China between December 1988 and March 1989. As primary isolation of influenza A (H1N2) viruses from humans had not been reported previously, it was of interest to determine the genetic origin of these virus isolates. The haemagglutinins of the H1N2 viruses were antigenically and genetically related to those of H1 viruses isolated world-wide since 1986, and the neuraminidases of these viruses were antigenically and genetically related to those of recent H3N2 viruses. Partial sequencing of each gene segment of three of the H1N2 viruses revealed that all gene segments except that encoding the haemagglutinin gene were derived from virus of the H3N2 subtype. Sequence differences amongst the neuraminidase, nucleoprotein and nonstructural genes of these three H1N2 reassortant viruses as well as the isolation of reassortants in seven laboratories over a 4 month period make it unlikely that the H1N2 viruses are laboratory artefacts. The spread of these reassortant viruses to other countries has not yet been documented.

Biopsy and autopsy specimens of liver tissues of two series of patients, one of adults and the other children suffering from hepatitis B virus (HBV) infection were used to evaluate hepatitis delta virus antigen (HDAg) by direct immunoperoxidase staining method. The results showed that four HDAg positive cases were found among 30 cases of HBV infected adult patients (13.3%), and 6 were found in 44 cases in the children series (13.6%). Therefore, we are convinced that hepatitis delta virus (HDV) superinfection does exist in Guangzhou area. The superinfection rates in adults and children are almost identical.

2346 liver samples from 17 areas in China were investigated for intrahepatic hepatitis D antigen (HDAg) by direct enzyme-labelled technique. HDAg was detected in 167 out of 1764 samples of HBsAg positive individuals with the detection rate of 9.47%. Hepatitis D virus (HDV) infection existed in all the examined areas without any significant difference regarding HDAg detection rate. A relationship of intrahepatic HDAg to the pathologic type of the liver disease was observed. The HDAg detection rate in chronic liver diseases and severe hepatitis was higher than in other liver diseases. It suggested that HDV infection was associated with the progression and chronicity of the liver disease. Studies on the relationship between HDV infection and HBV replication showed that HBV replication might be suppressed by HDV infection. Both HDV and HBV, however, could replicate in the same hepatocyte simultaneously.