Search

Objective: To identify measles vaccine failures in Tianjin, China using a measles virus IgG avidity assay., Methods: The China Information System for Disease Control and Prevention (CISDCP) was used to collect information about measles cases and blood specimens in Tianjin from 2013 to 2015. Measlesspecific IgM and IgG antibodies were detected using Enzyme-Linked Immunosorbent Assay (ELISA). Avidity testing for measles IgG was performed using a commercial enzyme immunoassay (EIA)., Results: A total of 284 confirmed measles cases were identified. Of this total, 262 (92.25%) were in patients aged ⪖ 20 years. High avidity was exhibited in 172 (60.56%) cases, while 80 (28.17%) cases demonstrated low avidity. High avidity was detected in only 21.43% of cases in patients aged < 1 year. The proportion of high avidity increased with age, and was significantly higher in patients aged 30-39 years at 70.07% (χ2 = 17.27, P = 0.002). Of the 52 measles cases in patients with a history of vaccinations, 41 (78.85%) cases showed high avidity, indicating secondary vaccine failures (SVF). In these vaccinations, there was no significant difference (P > 0.05) in clinical severity between high avidity and low avidity cases. However, regardless of vaccination status, clinical severity was significantly lower in high avidity cases (P < 0.001) than in low avidity cases. The percentages of positive measles IgM results in high avidity and low avidity cases were 66.28% and 91.25%, respectively. Geometric Mean Concentration (GMC) was significantly lower in high avidity cases at 33.73 U/mL, compared to 166.07 U/mL in low avidity cases., Conclusion: Low clinical severity and inconclusive IgM antibody results are more likely in high avidity measles cases. Measles cases were more common in adults. Therefore, a further dose of vaccines should be recommended for 30-39 years in Tianjin.., (Copyright © 2019 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.)

This study analyzed the genetic characterization on first imported measles virus of genotype D8 in Chinese mainland. Serums were collected from the suspicious MV patients to detect IgM antibody in ELISA. Throat swabs were cultured in Vero/SLAM cell line to get measles virus isolates. Part of the nucleotide sequence of the 3' terminus of nucleoprotein (N) gene of these isolates were amplified by RT-PCR, and the amplicons were directly sequenced. The phylogenetic analysis was based on the nucleotide sequence about 456 base pairs of the 3' terminus of nucleoprotein (N) gene. Results showed that it reported 1 105 suspicious measles cases in shanghai, 2012, including 590 confirmed cases and 2 clinical case. The reported morbidity was 2.52 per one hundred thousand. 247 measles viruses were isolated from 984 throat swabs specimen. Most of them belonged to sub-genotype H1a except Shanghai12-239 was genotype D8. The homology of nucleotide and amino acid sequences were 97.8% and 98.6% respectively between Shanghai12-239 and WHO reference strain (Manchester. UNK30.94(D8)AF280803). Those were 89.6%-94.5% and 88.7%-95.3% between Shanghai12-239 and WHO reference strains of other genotypes.

Objective: To carry out the molecular epidemiological study of the wild-type measles virus isolated in Qinghai Province during 2000-2011, and provide a scientific basis for the measles elimination., Methods: Measles viruses were isolated using B95a cell line or Vero/SLAM cell line from throat swabs collected from suspected measles cases during measles outbreak and sporadic in 6 prefectures during 2000-2011. The fragment of 696 nucleotides of N gene carboxy terminal was amplified by using RT-PCR methods. The PCR products were sequenced and analyzed. The phylogenetic tree was conducted with the viruses isolated in viruses from other province., Results: Total 19 measles viruses were isolated during 2000-2011 in Qinghai province and all belong to genotype H1a. The results of phylogenetic tree showed that viruses in 2000-2005 and in 2009-2011 were distributed in two different lineages, and it revealed that these strains belonged to at least 2 viral transmission chains and the viruses circulated during 2000-2005 were not detected after 2005., Conclusion: Genotype H1a was the predominant genotype circulated in Qinghai province during 2000-2011. Qinghai measles virus strains had not evolved independently, but coevolved with the measles virus strains in other provinces in mainland China. The variation of important amino acid sites of measles virus should be continuous monitored and provide the scientific strategy for the measles elimination.

Objective: To analyze the genetic characterizations of wild type measles viruses caused the measles outbreak in Xinjiang., Methods: Vero/Slam cell were used for measles viruses isolation from the specimens collected from measles outbreaks patients. Fragment of 676 nucleotide acids of the carboxylend of nucleoprotein gene were amplified using reverse transcription-polymerase chain reaction (RT-PCR) method and then the PCR products were directly sequenced and analyzed. Phylogenetic tree was constructed based on 450 nucleotide acids of the N-terminus of nucleoprotein gene, and homological analysis was performed at nucleotide acid level., Results: 11 measles viruses were sequenced and all belonged to H1a subgenotype. The nucleotide difference was 0-0.2% between 11 Xinjiang isolates. And the nucleotide difference was 2.2%-2.4% between Xinjiang isolates and H1 genotype reference strain., Conclusion: The Measles viruses causing the measles outbreak in Xinjiang were H1a subgenotype.

This study reported the first imported measles case associated with genotype D4 measles virus in Shanxi province in China. The clinical specimen of throat swab was inoculated into Vero/SLAM culture to isolate the virus. A RT-PCR (Reverse transcription polymerase chain reaction, RT-PCR) was performed to amplify the 676 nucleotides sequence corresponding to the carboxyl terminus of measles virus nucleoprotein. The phylogenetic tree based on the 450 nucleotide acids of carboxyl terminus of N protein was constructed and the homology similarity was analyzed. The Shanxi isolate MVi/Shanxi. CHN/20. 09/1 was clustered within the same genotype group with WHO genotype D4 reference strain, Montreal. CAN/89, and the homology of nucleotide acid between Shanxi isolate and WHO genotype D4 reference strain was 97.3%. The homology of nucleotide acid and amino acid between Shanxi isolate and 2009 genotype D4 representative strain circulating in USA, Canada, India and Russian were 98.0%-100% and 97.3%-100%, respectively. These results showed that the virus isolated from the imported measles case was genotype D4. This is the first report that the genotype D4 measles virus was imported and isolated in China. It is important to accumulate baseline data of China and help to measure transmission pathways and to clarify epidemiological links.

Objective: To study the genotype and gene characterization of measles wild viruses circulated in Jilin provinces, and to provide scientific evidences for setting down controlling and preventing strategy and measures., Methods: 38 strains of measles virus isolated in 2001-2006 were genotyped by RT-PCR-RFLP, some strains of measles virus in Jilin province were chosen for the phylogenetic analysis and for the homology analysis of nucleotide and amino acid sequences., Results: All the 38 strains of measles virus were identified as H1 genotype by RT-PCR-RFLP, and 29 strains of them were identified further as H1 a by sequence analysis. The homology of nucleotide was 88.0%-89.4% and the homology of amino acid was 91.8%-92.7% .The average diversity was less than 1.4%., Conclusion: The measles virus of H1a genotype was the circulating virus within recent years in Jilin province. There were the same measles virus strains circulating and transmitting at different years and also the different H1a measles virus strains co-circulating at the same year. There were the same transmission chain caused by the same measles virus with other provinces.

Objective: A new simple RT-LAMP method was applied to detect measles virus nucleic acid and compared with nest-RT-PCR., Methods: Compare the detection rate of the RT-LAMP method with that of nest-RT-PCR by detecting measles virus nucleic acid from measles virus and clinical samples., Results: The nucleic acid positive rates of all 23 strains of measles virus are all 100% by the two methods. But to the detection of 18 clinical samples which are negative in measles isolation, the nest-RT-LAMP showed 56.52% positive rate of nucleic acid of measles virus and nest-RT-PCR showed 47.83%., Conclusion: RT-LAMP is more sensitive than nest-RT-PCR.

Objective: To develop pathogenic surveillance on measles and to effectively isolate measles virus. To know the genetic characterizations and molecular epidemiology of wildtype measles viruses from 2005 to 2007 in Guangdong Province, and provide the scientific basis for measles control and eradication., Methods: Vero/Slam cell line were used, measles viruses were isolated from throat swabs or urine specimens collected from uspected measles patients in outbreaks and sporadic patients. A 450 nucleotides fragment of the C-terminal of the nucleoprotein (N) gene was amplified and by RT-PCR and subjected to sequence and phylogenetic analysis using Bio-Edit software., Results: 82 wild-type measels virus were obtained from 377 throat swabs and urine specimens from 2005 to 2007 in Guangdong Province measles lab. The measles isolation rate was 23.58% in 2005, 17.11% in 2006, 39.13% in 2007. The succeed rate of virus isolation is related to the quality of specimens collected and the days after rash occurrence., Conclusions: We have grasped the technicalability of measles virus isolation and confirm action, and got higher isolation ratio. The wild-type measles virus isolated from Guangdong Province is of H1 genotype from 2005 to 2007, which is the same as the dominant genotype circulation.

Objective: To study the genetic characterization of wild-type measles viruses isolated in Xinjiang in 2003 and 2004., Methods: Peripheral blood mononuclear cells (PBMC) from 19 suspected measles cases collected between June 2003 and April 2004 were used to isolate measles virus by cocultivation with phytohemagglutinin (PHA)-stimulated cord blood mononuclear cells (CBMC). For positive samples, 676 nucleotides of the C-terminus of the nucleoprotein (N) gene of the measles virus genome were amplified by reverse transcription-polymerase chain reaction and then sequenced. These sequences were compared with those of other measles reference strains available in GenBank or measles isolates elsewhere in China using BLAST searches and phylogenetic analyses., Results: 6 measles virus strains were isolated with 3 strains (XJ03-26, XJ03-27, XJ03-74) from 2003 and 3 (XJ04-146, XJ04-150, XJ04-152) from 2004. The strain XJ03-26, differed from the Chinese measles vaccine strain S-191 (genotype A) by less than 1% at nucleotide level, and therefore appeared a vaccine-associated strain. The other 5 strains as XJ03-27, XJ03-74, XJ04-146, XJ04-150 and XJ04-152 were proved to be genotype H1 strains,among which XJ03-27, XJ03-74, XJ04-150 and XJ04-152, showing their nucleotide diversity were varied from 0.5% to 1.6%, when compared to the H1a reference strain China9322, and identified as H1a strains. XJ04-146 showed a nucleotide similarity of 98.7% when compared to H1b reference strain China9475, and was identified as H1b strain. Additionally, we found that there were two sets of strain (XJ03-27 and XJ04-150; XJ03-74 and XJ04-152), with almost identical nucleotide sequences, circulating in 2003 and 2004 and both having more nucleotide variability (up to 6.1%, 27 nucleotides)., Conclusion: Genotype H1 measles virus had been proven to have been circulated in Xinjiang, China during 2003 and 2004. H1a was the predominant epidemic strain while H1b strain stood the next.

Objective: To investigate genotype of wild-type measles viruses circulated in Beijing in 2003., Methods: Throat swabs specimens were collected from patients seen during an outbreak of measles and from clinically suspected sporadic measles patients in 2003. Vero/SLAM cell lines recommended by WHO were used to isolate measles virus. Four hundreds and fifty nucleotides of COOH-terminal of nucleoprotein (N) genes were amplified by using PR-PCR. The amplified products were sequenced and the sequences were compared with references viruses from GeneBank., Results: Eight strains of measles viruses were isolated from throat swabs of patients who came from seven districts and counties of Beijing. Sequence analysis of the 450 nucleotides of COOH-terminal of nucleoprotein (N) genes indicated that these 8 strains belonged to H1a genotype. The average genetic distances of these 8 strains to H1a genotype, Chin9322, H1b genotype, Chin9475 and H1c genotype, Chin9427, were 0.004 - 0.011, 0.026 - 0.031 and 0.015 - 0.022, respectively. The average genetic distances of these 8 strains to H1a genotype, Anhui 01 - 1/Anhui 02 - 2, were 0.000 - 0.009 (0 - 5 nucleotide variation)., Conclusions: Major genotypes of wild-type measles viruses circulated in Beijing in 2003 were H1a genotype. The genotypes H1c, H1b and H2 may have disappeared in Beijing.