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Background Influenza A H5N1 has killed millions of birds and raises serious public health concern because of its potential to spread to humans and cause a global pandemic. While the early focus was in Asia, recent evidence suggests that Egypt is a new epicenter for the disease. This includes characterization of a variant clade 2.2.1.1, which has been found almost exclusively in Egypt. We analyzed 226 HA and 92 NA sequences with an emphasis on the H5N1 2.2.1.1 strains in Egypt using a Bayesian discrete phylogeography approach. This allowed modeling of virus dispersion between Egyptian governorates including the most likely origin. Results Phylogeography models of hemagglutinin (HA) and neuraminidase (NA) suggest Ash Sharqiyah as the origin of virus spread, however the support is weak based on Kullback- Leibler values of 0.09 for HA and 0.01 for NA. Association Index (AI) values and Parsimony Scores (PS) were significant (p-value < 0.05), indicating that dispersion of H5N1 in Egypt was geographically structured. In addition, the Ash Sharqiyah to Al Gharbiyah and Al Fayyum to Al Qalyubiyah routes had the strongest statistical support. Conclusion We found that the majority of routes with strong statistical support were in the heavily populated Delta region. In particular, the Al Qalyubiyah governorate appears to represent a popular location for virus transition as it represented a large portion of branches in both trees. However, there remains uncertainty about virus dispersion to and from this location and thus more research needs to be conducted in order to examine this. Phylogeography can highlight the drivers of H5N1 emergence and spread. This knowledge can be used to target public health efforts to reduce morbidity and mortality. For Egypt, future work should focus on using data about vaccination and live bird markets in phylogeography models to study their impact on H5N1 diffusion within the country. [ABSTRACT FROM AUTHOR]

Abstract: We characterized Influenza A/H5N1 virus that caused the first outbreak of highly pathogenic avian influenza (HPAI) in chickens in Bhutan in 2010. The virus was highly virulent to chicken, killing them within two days of the experimental inoculation with an intravenous pathogenicity index (IVPI) of 2.88. For genetic and phylogenetic analyses, complete genome sequencing of 4 viral isolates was carried out. The isolates revealed multiple basic amino acids at their hemagglutinin (HA) cleavage site, similar to other “Qinghai-like” H5N1 isolates. The receptor-binding site of HA molecule contained avian-like amino acids (222Q and 224G). The isolates also contained amino acid residue K at position 627 of the PB2 protein, and other markers in NS 1 and PB1 proteins, highlighting the risk to mammals. However, the isolates were sensitive to influenza drugs presently available in the market. The sequence analysis indicated that the Bhutan viruses shared 99.1–100% nucleotide homology in all the eight genes among themselves and 2010 chicken isolate from Bangladesh (A/chicken/Bangladesh/1151-11/2010) indicating common progenitor virus. The phylogenetic analysis indicated that the Bhutan isolates belonged to sub-clade 2.2.3 (EMA 3) and shared common progenitor virus with the 2010 Bangladesh virus. Based on the evidence of phylogeny and molecular markers, it could be concluded that the outbreaks in Bhutan and Bangladesh in 2010 were due to independent introductions of the virus probably through migratory birds. [Copyright &y& Elsevier]

The article discusses a study which examined Japanese pigeons with H5N1 highly pathogenic avian influenza (HPAI) viruses to evaluate their possible role in virus transmission to poultry. Topics discussed include the limited susceptibility of pigeons to the virus, serological analysis showing that chickens did not exhibit seroconversion after close contact with inoculated pigeons, and the risk posed by pigeons in terms of transmission of the virus to poultry compared with other avian species.

Abstract: One influenza pandemic preparedness strategy involves priming a population with a pre-pandemic subtype-specific vaccine and boosting the immunological response at the time of the pandemic with a strain-matched vaccine. In the current study, adults (n =469) randomised 15 months previously to receive an A/Indonesia/5/2005 (H5N1) influenza vaccine (3.75μg haemagglutinin antigen [HA]) administered alone or in combination with an oil-in-water emulsion based Adjuvant System containing 11.86mg (AS03A) or 5.93mg (AS03B) tocopherol per dose, received one booster dose of A/turkey/Turkey/1/2005 (H5N1) vaccine (3.75μg HA) with or without AS03A. An anamnestic antibody response that met US regulatory acceptance criteria was observed 15 months after priming. Although superior immunogenicity of AS03-adjuvanted compared to unadjuvanted priming was not demonstrated, higher antibody titres which persisted longer were seen when both priming and boosting regimens were adjuvanted. This may affect duration of response or heterologous immunity. The booster vaccines had a clinically acceptable safety/reactogenicity profile after adjuvanted or unadjuvanted priming. This study has been registered at www.clinicaltrials.gov NCT00771615. [Copyright &y& Elsevier]

Abstract: Outbreaks of H5N1 avian influenza virus were reported in 15 districts of West Bengal State in India in early 2008 and subsequent re-occurrence in 5 districts in December, 2008 to May, 2009. We have sequenced complete genome of 12 viruses isolated from early 2008 outbreak and from recurrent outbreak and determined the phylogenetic relationship between the viruses isolated from the two outbreaks. One of the virus isolated in early 2008 from Malda district (A/chicken/West Bengal/81760/2008) clustered with Korean and Russian isolates of 2006 in European-Middle Eastern-African (EMA) 3 sub-lineage of sub-clade 2.2, whereas other viruses showed close genetic relationship with 2007–2009 isolates of Bangladesh. Nucleotide sequence analysis revealed that the PB1-F2 protein expression might be completely abolished due to mutated start codon (95ATG97 → 95ACG97) in this isolate but in all other isolates it was completely expressed. Hence, we conclude that there were two separate introductions of H5N1 viruses in Malda district and this H5N1 virus was not epidemiologically dominant as the viruses isolated subsequently from the same district and region did not share close relationship with this virus. The failure of this virus to spread to adjoining areas suggests that the culling and disposal operations initiated by Government of India were effective. [Copyright &y& Elsevier]

This study reports the genetic characterization of highly pathogenic avian influenza (HPAI) virus (subtype H5N1) isolated from poultry in West Bengal, India. We analyzed all the eight genome segments of two viruses isolated from chickens in January 2010 to understand their genetic relationship with other Indian H5N1 isolates and possible connection between different outbreaks. The hemagglutinin (HA) gene of the viruses showed multiple basic amino acids at the cleavage site, a marker for high virulence in chickens. Of greatest concern was that the viruses displayed amino acid substitution from serine-to-asparagine at position 31 of M2 ion channel protein suggesting emergence of amantadine-resistant mutants not previously reported in HPAI H5N1 outbreaks in India. Amino acid lysine at position 627 of the PB2 protein highlights the risk the viruses possess to mammals. In the phylogenetic trees, the viruses clustered within the lineage of avian isolates from India (2008-2009) and avian and human isolates from Bangladesh (2007-2009) in all the genes. Both these viruses were most closely related to the viruses from 2008 in West Bengal within the subclade 2.2.3 of H5N1 viruses. [ABSTRACT FROM AUTHOR]

The apparent family clustering of avian influenza A/H5N1 has led several groups to postulate the existence of a host genetic influence on susceptibility to A/H5N1, yet the role of host factors on the risk of A/H5N1 disease has received remarkably little attention compared to the efforts focused on viral factors. We examined the epidemiological patterns of human A/H5N1 cases, their possible explanations, and the plausibility of a host genetic effect on susceptibility to A/H5N1 infection. The preponderance of familial clustering of cases and the relative lack of non-familial clusters, the occurrence of related cases separated by time and place, and the paucity of cases in some highly exposed groups such as poultry cullers, are consistent with a host genetic effect. Animal models support the biological plausibility of genetic susceptibility to A/H5N1. Although the evidence is circumstantial, host genetic factors are a parsimonious explanation for the unusual epidemiology of human A/H5N1 cases and warrant further investigation. [ABSTRACT FROM AUTHOR]

Abstract: Our aim was to characterize the A/ck/Israeli/1055/2008 (H5N1) avian influenza virus that was isolated at the beginning of 2008, and to establish the phylogenetic relationship of this isolate to other H5N1 viruses that were recently isolated in adjacent countries. In light of a study of complete nucleotide sequences of all the genes we found that the isolate (year 2008) was closely related to the H5N1 viruses isolated in Egypt, Israel and Gaza in 2006. The Israeli isolate had the hemagglutinin-connecting peptide with a polybasic amino acid insertion. The most host-restriction sites of the 2008 isolate were typical of avian hosts, with one exception: K627 at the PB2 protein. As compared with previous local H5N1 isolates, a high mutation rate was found at the HA gene, which antigenic sites were under positive selection pressure. [ABSTRACT FROM AUTHOR]

The article presents a study on the endemic status of highly pathogenic influenza H5N1 virus in wildlife in the Lake Qinghai area of northwest China. For the study, researchers initiated a continuous surveillance scheme from September 2005 to September 2007. They gathered 2,699 field samples in which 95 were found to be positive of the virus through a reverse transcription-polymerase chain reaction (RT-PCR) test of subtype H5 influenza virus. They found two 2007 isolates manifested more similarities of the hemagglutinin and neuraminidase genes with those of the 2005 and 2006 isolates.

Copyright of Avian Diseases is the property of American Association of Avian Pathologists, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Avian Diseases is the property of American Association of Avian Pathologists, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Since 1997, human infections with highly pathogenic zoonotic avian influenza viruses hive shown that the risk of influenza pandemic is significant. In Europe, infections caused by the highly pathogenic avian influenza A(H7N7) virus were confirmed in the human population in 2003 in the Netherlands. Moreover, outbreaks of A(H5N1) infections were observed in wild and farm birds in different European regions, including Poland in 2006-2008. This study presents 16 patients in Poland from whom clinical specimens were collected and tested for A(H5N1) highly pathogenic avian influenza. This article shows the results of laboratory tests and discusses the legitimacy of the collection and testing of the specimens. All patients were negative for A(H5N1) infection. Nevertheless, only two patients met clinical and epidemiological criteria from the avian influenza case definition. The conclusion is that there is still a strong necessity for increasing the awareness of medical and laboratory staff, as well as the awareness of sonic occupational groups about human infections with avian influenza viruses, including the importance of seasonal influenza vaccination, It should also be emphasized that in the case of patients suspected of being infected with avian influenza, the information about clinical symptoms is insufficient and must be accompanied by a wide epidemiological investigation. [ABSTRACT FROM AUTHOR]

Abstract: The wide distribution of H5N1 highly pathogenic avian influenza viruses is a global threat to human health. Indonesia has had the largest number of human infections and fatalities caused by these viruses. To understand the enzootic conditions of the viruses in Indonesia, twenty-four H5N1 viruses isolated from poultry from 2003 to 2007 were phylogenetically characterized. Although previous studies exclusively classified the Indonesian viruses into clades 2.1.1–2.1.3, our phylogenetic analyses showed a new sublineage that did not belong to any of the present clades. In addition, novel reassortant viruses were identified that emerged between this new sublineage and other clades in 2005–2006 on Java Island. H5N1 viruses were introduced from Java Island to Sulawesi, Kalimantan, and Sumatra Island on multiple occasions from 2003–2007, causing the geographical expansion of these viruses in Indonesia. These findings identify Java Island as the epicenter of the Indonesian H5N1 virus expansion. [Copyright &y& Elsevier]

Summary: The viral dissemination in a patient with avian influenza A subtype H5N1 infection was retrospectively studied by the immunohistochemical localization of viral nucleoprotein antigen. The pathology was marked by diffuse alveolar damage, lymphoid depletion, and reactive hemophagocytic syndrome. Besides the lung and the upper respiratory tract, viral antigen was detected in the small and large intestinal epithelial cells, hematopoietic cells in the bone marrow, glial cells and neurons of the brain, and lymphocytes. The results confirmed that H5N1 virus disseminated to multiple organs beyond the respiratory system. However, specific pathological changes were noted in the respiratory system only, and productive viral replication confirmed by culture was noted only in the lung. More postmortem studies are needed to elucidate the pathogenesis of this highly fatal zoonotic disease. [Copyright &y& Elsevier]

Objectives: This article aims to quantify the risk factors associated with the human cases of HSN1 avian influenza in South-east Asian countries and China; a dangerous region for this disease that has the potential for a pandemic outbreak. Study design: A statistical model with time and spatial dimensions was built to capture the international spread patterns of this disease. Methods: The grid search method was used to fit the model with 2004-2006 data. The grid search approach is a simple procedure that allows the fit of any function to data. Results: This study found that: (1) when the number of domestic HSN1 human cases increases by one person in a certain time period, the chance that the country will have a human case in the next period increases by 22.10%; (2) when the number of human cases in a neighbouring country increases by one person in a certain time period, the chance that the country will have a human case in the next period increases by 1.62%; (3) when the number of avian cases in a neighbouring country increases by one, the chance that the country will have a human case increases by 0.02%; (4) as the human population increases by one unit, the chance that the country will have a human case increases by 0.10%; (5) when the quantity of imported poultry increases by 1000 metric tons, the chance that the country will have a human case increases by 0.03%; (6) when the outbreak of the disease among domestic birds increases by one, the chance that the country will have a human case increases by 0.19%; and finally (7) when the number of birds destroyed increases by 1000, the chance that the country will have a human case decreases by 0.30%. Conclusions: These findings shed new light on the spatiotemporal characteristics of the epidemic, and thus need to be taken into consideration in interdisciplinary and scientific discussion of the disease. [ABSTRACT FROM AUTHOR]

In view of the tenacity of viruses in the feathers, many workers have suggested the importance of using feathers as the diagnostic material for epidemiological surveillance of highly pathogenic avian influenza (HPAI) H5N1 virus infections. In this study, we have compared the efficiency of two different processing methods, immersion method and trituration method for elution of HPAI H5N1 virus from the feathers of avian influenza negative ducks in terms of virus isolation in 9-to 11-day-old embryonated specific pathogen free chicken eggs and viral RNA detection by haemagglutinin gene based real-time RTPCR. The recovery of virus by immersion method in terms of percent infectivity in 3 replicates was 96.67, 93.33 and 96.67, whereas in trituration method, percent infectivity was 26.67, 20 and 16.67. In real-time RTPCR, viral RNA could be detected in 17 out of 18 samples by immersion method and from only 2 out of 18 samples by trituration method. The study revealed that the immersion method gave higher viral infectivity percentage and could also be easily detected by real-time RTPCR. We conclude that immersion method of virus elution could be useful for processing of shed duck feathers present in the environment for epidemiological screening against HPAI H5N1 virus infections. [ABSTRACT FROM AUTHOR]

Abstract: DNA vaccination is an effective means of eliciting both humoral and cellular immunity. Most of influenza vaccines targeted at hemagglutinin (HA) show efficient immunogenicity for protecting subjects against influenza virus infection. However, major antigenic variations of HA may facilitate the virus in developing resistance against such vaccines. DNA vaccines encoding conserved antigens protect animals against diverse viral subtypes, but their potency requires further improvement. In the present study, a DNA vaccine encoding the conserved nucleoprotein (NP) with a tissue plasminogen activator (tPA) signal sequence (ptPAs/NP) was generated, and immune responses were examined in vaccinated mice. A higher level of NP expression and secretion was observed in lysates and supernatants of the cells transfected with ptPAs/NP when compared to a plasmid encoding the wild-type full-length NP (pflNP). Immunofluorescence studies showed the cytoplasmic localization of the NP protein expressed from ptPAs/NP, but not from pflNP. In mice, the ptPAs/NP vaccine elicited higher levels of the NP-specific IgG and CD8+ T cell-stimulating responses than that of pflNP. Vaccination with ptPAs/NP efficiently cleared the homologous H5N1 influenza virus in the infected lungs and induced partial cross-protection against heterologous, highly pathogenic H5N1 strains in mice. Our results may contribute to the development of protective immunity against diverse, highly pathogenic H5N1 virus subtypes. [Copyright &y& Elsevier]

Abstract: The avian H5N1 influenza virus has the potential to cause a new pandemic. Since it is difficult to predict which strain of influenza will cause a pandemic, it is advantageous to produce vaccines that confer cross-protective immunity. Mucosal vaccine administration was reported to induce cross-protective immunity by inducing secretion of IgA at the mucosal surface. Adjuvants can also enhance the development of fully protective mucosal immunity. Here we show that a new mucosal adjuvant, polyI:polyC12U (Ampligen®), a Toll-like receptor 3 agonist proven to be safe in a Phase III human trial, is an effective adjuvant for H5N1 influenza vaccination. Intranasal administration of a candidate influenza vaccine with Ampligen resulted in secretion of IgA, and protected mice that were subsequently challenged with homologous A/Vietnam/1194/2004 and heterologous A/HK/483/97 and A/Indonesia/6/2005 virus. [Copyright &y& Elsevier]

Background Influenza A viruses are classified into subtypes depending on the antigenic properties of their two outer glycoproteins, hemagglutinin (HA) and neuraminidase (NA). Sixteen subtypes of HA and nine of NA are known. Lately, the circulation of some subtypes (H7N7, H5N1) has been closely watched because of the epidemiological threat they present. Objectives This study assesses the potential of using gel-based microchip technology for fast and sensitive molecular subtyping of the influenza A virus. Methods The method employs a microchip of 3D gel-based elements containing immobilized probes. Segments of the HA and NA genes are amplified using multiplex RT-PCR and then hybridized with the microchip. Results The developed microchip was validated using a panel of 21 known reference strains of influenza virus. Selected strains represented different HA and NA subtypes derived from avian, swine and human hosts. The whole procedure takes 10 hours and enables one to identify 15 subtypes of HA and two subtypes of NA. Forty-one clinical samples isolated during the poultry fall in Novosibirsk (Russia, 2005) were successfully identified using the proposed technique. The sensitivity and specificity of the method were 76% and 100%, respectively, compared with the ‘gold standard’ techniques (virus isolation with following characterization by immunoassay). Conclusions We conclude that the method of subtyping using gel-based microchips is a promising approach for fast detection and identification of influenza A, which may greatly improve its monitoring. [ABSTRACT FROM AUTHOR]

The panzootic of H5N1 influenza in birds has raised concerns that the virus will mutate to spread more readily in people, leading to a human pandemic. Mathematical models have been used to interpret past pandemics and outbreaks, and to thus model possible future pandemic scenarios and interventions. We review historical influenza outbreak and transmission data, and discuss the way in which modellers have used such sources to inform model structure and assumptions. We suggest that urban attack rates in the 1918–1919 pandemic were constrained by prior immunity, that R0 for influenza is higher than often assumed, and that control of any future pandemic could be difficult in the absence of significant prior immunity. In future, modelling assumptions, parameter estimates and conclusions should be tested against as many relevant data sets as possible. To this end, we encourage researchers to access FluWeb, an on-line influenza database of historical pandemics and outbreaks. [ABSTRACT FROM AUTHOR]

Abstract: An H5N1 influenza A virus was isolated from duck meat processed for human consumption, imported to Japan from Shandong Province, China in 2003. This virus was antigenically different from other H5 viruses, including the Hong Kong H5N1 viruses isolated from humans in 1997 and 2003. Sequence analysis revealed that six genes (PB1, PA, HA, NA, M, and NS) of this virus showed > 97% nucleotide identity with their counterparts from recent H5N1 viruses, but that the remaining two genes (PB2 and NP) were derived from other unknown viruses. This duck meat isolate was highly pathogenic to chickens upon intravenous or intranasal inoculation, replicated well in the lungs of mice and spread to the brain, but was not as pathogenic in mice as H5N1 human isolates (with a dose lethal to 50% of mice (MLD50) = 5 × 106 50% egg infectious doses [EID50]). However, viruses isolated from the brain of mice previously infected with the virus were substantially more pathogenic (MLD50 = ∼102 EID50) and possessed some amino acid substitutions relative to the original virus. These results show that poultry products contaminated with influenza viruses of high pathogenic potential to mammals are a threat to public health even in countries where the virus is not enzootic and represent a possible source of influenza outbreaks in poultry. [Copyright &y& Elsevier]

Abstract: In Japan, between the end of December 2003 and March 2004, four outbreaks of acute, highly transmissible and lethal disease occurred in birds in three prefectures separated by 150–450 km, involving three chicken farms and a group of chickens raised as pets. The cause of each outbreak was an H5N1 influenza A virus—the first highly pathogenic virus to be isolated from the outbreaks in Japan since 1925. The H5N1 virus was also isolated from dead crows, apparently infected by contact with virus-contaminated material. These H5N1 viruses were antigenically similar to each other, but could be differentiated from other H5 viruses, including those isolated from Hong Kong in 1997 and 2003, by use of a panel of monoclonal antibodies in hemagglutination inhibition assays. Genetically, the H5N1 viruses in Japan were closely related to each other in all genes and were genetically closely related to a single isolate of genotype V that was isolated in 2003 in the Guandong Province of mainland China (A/chicken/Shantou/4231/2003). The virulence of the index isolate (A/chicken/Yamaguchi/7/2004) was studied in chickens and mice. Chickens intravenously or intranasally inoculated with the isolate died within 1 or 3 days of inoculation, respectively. In mice, although this virus replicated well in the lung without prior adaptation and spread to the brain, the dose lethal to 50% of the mice was 5 × 105 50% egg infectious doses (EID50), which is less pathogenic than the Hong Kong 1997 H5N1 viruses isolated from humans. Our findings indicate that the H5N1 viruses associated with the influenza outbreaks in chickens in Japan were genotypically closely related to an H5N1 virus isolated from chicken in China in 2003 (genotype V), but were different from those prevalent in southeastern Asia in 2003–2004 (i.e., genotype Z) and that these highly pathogenic viruses can be transmitted to crows, which are highly susceptible to these viruses. [Copyright &y& Elsevier]

In Hong Kong in 1997, an avian H5N1 influenza virus was found for the first time to be transmitted from poultry to humans. Of the 18 infected persons, 6 (33%) died. In February 2003 in Hong Kong, avian H5N1 virus was again transmitted to humans; one of the two infected persons died. Here we provide an overview of the pathogenicity of H5N1/97 viruses in mammals. In addition, we present recent findings on the effect of single viral-gene mutations on pathogenicity in mice and discuss the influence of the H5N1/97 NS gene on pathogenicity in pigs and mice. Finally, we discuss the possibility that in some instances the unusual severity of H5N1 virus-induced disease in mice is due to a cytokine imbalance caused by the virus''s NS gene. [Copyright &y& Elsevier]

Both H5N1 and H7N9 subtype avian influenza viruses cause enormous economic losses and pose considerable threats to public health. Bivalent vaccines against both two subtypes are more effective in control of H5N1 and H7N9 viruses in poultry and novel egg-independent vaccines are needed. Herein, H5 and H7 virus like particle (VLP) were generated in a baculovirus expression system and a bivalent H5+H7 VLP vaccine candidate was prepared by combining these two antigens. Single immunization of the bivalent VLP or commercial inactivated vaccines elicited effective antibody immune responses, including hemagglutination inhibition, virus neutralizing and HA-specific IgG antibodies. All vaccinated birds survived lethal challenge with highly pathogenic H5N1 and H7N9 viruses. Furthermore, the bivalent VLP significantly reduced viral shedding and virus replication in chickens, which was comparable to that observed for the commercial inactivated vaccine. However, the bivalent VLP was better than the commercial vaccine in terms of alleviating pulmonary lesions caused by H7N9 virus infection in chickens. Therefore, our study suggests that the bivalent H5+H7 VLP vaccine candidate can serve as a critical alternative for the traditional egg-based inactivated vaccines against H5N1 and H7N9 avian influenza virus infection in poultry., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Hu, Peng, Li, Zhang, Li, Wang, Gu, Hu, Hu, Liu, Jiao, Peng and Liu.)

Since 1997, the largest epidemic of highly pathogenic avian influenza (H5N1) ever recorded has caused 172 human and several billion bird deaths. Recently administered questionnaires determined that live poultry exposures have declined by ≈63% in Hong Kong since 2004 and that, in Vietnam, domestic backyard exposures to poultry are likely more important than retail exposures.

The article details a study which examined the efficacy of inactivated H5N1 avian influenza (AI) vaccine in protecting chickens against different highly pathogenic H5N1 avian influenza viruses isolated in China and Vietnam. The study included groups of three-week-old specific-pathogen-free chickens that were intramuscularly injected with one dose of the vaccine. It found that H5N1 A/goose/Guangdong/1/96 (GS/GD/06)-based vaccine offers sound protection against clade 1, 2.2 and 3.3.4 viruses but not A/chicken/Shanxi/2/06 (CK/SX/06) virus. Study authors concluded that the antigenic match between inactivated vaccine and circulating virus can determine the efficacy of a vaccine in preventing H5N1 influenza virus replication and transmission.

The article discusses the susceptibility of whooper swans on contacting the avian flu virus (H5N1) due to its migration behaviors. It notes that the swans infected with H5N1 display asymptomatic characteristics. The immunohistochemical tests demonstrate the presence of virus antigens on feather epidermis. It cites the application of genetic sequence using paraffin section which confirmed the avian influenza virus on swans. Moreover, it suggests that feathers increase the risk of zoonotic infection on wild swans.