Virological characterization of influenza A(H3N2) virus in Mainland China during 2011-2012 / 病毒学报

To study the prevalence and variation of influenza A(H3N2) viruses, the antigenic and genetic characteristics of influenza A(H3N2) viruses circulating in Mainland China during April 2011 to March 2012 were analyzed. The results showed that influenza A(H3N2) viruses increased gradually since 2012 and became the dominant strain since March. The viruses were antigenically closely related to the vaccine strain A/PER/16/09 (87.2%) and the representative virus A/FJ/196/09 (76.0%) in Mainland China. The genetic characteristics analysis results showed that recently isolated viruses belonged to the Vic/208 clade, and most of the low reaction strains also fell into the same clade. Crystal structure analysis of HA protein found that, compared with the vaccine strain A/PER/16/09, the recently isolated viruses had amino acid substitutions in the antigenic site A, B and C areas, in addition to gaining potential glycosylation sites at the amino acid position of 45 of HA and 367 of NA. Although the majority of circulating influenza A (H3N2) viruses in 2011-2012 season in Mainland China were antigeniclly matched by current influenza vaccine strain and the selected representative viruses, low reaction strains have increased since 2012, therefore it is necessary to strengthen the surveillance on the variation of influenza virus and to provide solid information for the vaccine strain selection.

Development of a real-time reverse transcriptase PCR assay for detection of E119V amino acid change in neuraminidase of influenza A (H3N2) using the TaqMan-MGB probe / 中华预防医学杂志

<p><b>OBJECTIVE</b>To develop a rapid duplex Real-time reverse transcription PCR (rRT-PCR) method to detect E119V mutation on neuraminidase (NA) of influenza A(H3N2) subtype with drug resistance to oseltamivir.</p><p><b>METHODS</b>Twenty-six NA genes of influenza A(H3N2) virus between 2000 and 2012 in GenBank database were selected as the target genes, and specific TaqMan-MGB probe was designed to target the E119V amino acid change in neuraminidase protein. rRT-PCR was then performed and evaluated for the sensitivity, specificity and reproducibility using virus with E119V mutation and clinical samples.</p><p><b>RESULTS</b>This study described the validation of a highly sensitive and specific duplex rRT-PCR for detection of substitutions leading to the E119V amino acid change in NA protein of influenza A(H3N2). Fluorescence signals could be detected even when diluted a A (H3N2) virus (HA = 8) into 10(-5) and linear correlation between the logarithm of the viral titer with the Ct values was observed. In addition, the assay was highly specific in that there was no cross-react with other respiratory viruses, nor did two TaqMan-MGB probes. E119V substitution in quasispecies with both sensitive and resistant viruses could be detected as well. The limit of detection was 5% for quasispecies with high concentrations and 50% for quasispecies with low concentrations. The average coefficient of variation (CV) for within-run assays was 2.32% and 0.57% for H3N2-119E and H3N2-119V primer/probe sets separately, 1.77% and 0.97% for average CV of between-run assays, which exhibited good repeatability. Sequence analysis of twenty NA genes verified glutamic acid (E) at amino acid site 119, which was in consistent with the results from our rRT-PCR method.</p><p><b>CONCLUSION</b>The assay developed in this study is highly sensitive and specific, and easy to operate; thereby it could be used for identification of A(H3N2) virus with E119V amino acid change in NA protein.</p>

Virological characterization of influenza B virus in mainland China during 2011-2012 / 病毒学报

In order to understand the prevalence and variation of influenza B viruses, the antigenic and genetic characteristics of influenza B viruses circulating in Mainland China during April, 2011 to March, 2012 were analyzed. The results showed the B Victoria lineage viruses were much more prevalent than B Yamagata lineage during this period, phylogenetic analysis showed vast majority of Victoria lineage viruses belong to genetic group 1, intra-clade reassortant between HA1 and NA gene was identified in a minor proportion of the viruses. 72.8% of the B/Victoria-lineage viruses were antigenically closely related to the vaccine strain B/Brisbane/60/2008. B Yamagata component was not included in the trivalent influenza vaccine in China during the study period, however vast majority of B Yamagata lineage viruses were antigenically and genetically closely related to the representative virus B/Hubei-Wujiagang/158/2009(97.8%) and B/Sichuan-Anyue/139/2011(85.2%) in China, reassortant between HA1 and NA was not identified in B Yamagata lineage viruses. Overall, the predominant circulating influenza B viruses in 2011-2012 season in China were matched by current influenza vaccine and the selected representative viruses were proved to represent the antigenic and genetic characteristics of the circulating viruses.

Emerged Pdm09 influenza virus increased purifying selection of seasonal H1N1 influenza virus / 病毒学报

Pdm09 virus outbreak occurred in Mainland China in May 2009, a few months later, the prevalence of seasonal H1N1(sH1N1) influenza virus that already circulated in human for tens of years began to decline and disappeared afterwards. To identify the reason for the rapid decline of sH1N1 in mainland China, we sequenced the HA1 of sH1N1 during 2006-2011, and then analyzed the selective pressure in different phases. Our results showed before Pdm09 outbreak, the omega value was 0. 36 while after Pdm09 outbreak the omega value was 0. 28 and significant difference (t test, P<0. 05) was identified. We concluded that sH1N1 obtained stronger purifying selection after Pdm09 outbreak in China. This might one of the major reasons causing the disappearance of sH1N1 in human.

Development of multi-pathogen detection techniques for respiratory viruses / 病毒学报

Viral respiratory tract infection is among the leading causes of mortality and morbidity worldwide. Rapid screening methods for multiple detection of a wider range of pathogens become very important for diagnosis of respiratory infection. This article describes conventional detection technologies and several emerging multiplex assays that have potential applications in the diagnosis and monitoring of respiratory viral infections. These techniques include new rapid culture system, multiplex reverse transcription-PCR, real-time reverse transcription PCR, solid and suspension microarrays, mass spectrometry as well as metagenomics methods. The development and application of these techniques will not only improve the ability of rapid detection and control of viral respiratory infection, but play pivotal roles in the rapid characterization of new viral pathogens.