Interferon-induced Transmembrane Protein 3 Prevents Acute Influenza Pathogenesis in Mice / 生物医学与环境科学（英文）

Objective@#Interferon-induced transmembrane protein 3 (IFITM3) is an important member of the IFITM family. However, the molecular mechanisms underlying its antiviral action have not been completely elucidated. Recent studies on IFITM3, particularly those focused on innate antiviral defense mechanisms, have shown that IFITM3 affects the body's adaptive immune response. The aim of this study was to determine the contribution of IFITM3 proteins to immune control of influenza infection .@*Methods@#We performed proteomics, flow cytometry, and immunohistochemistry analysis and used bioinformatics tools to systematically compare and analyze the differences in natural killer (NK) cell numbers, their activation, and their immune function in the lungs of -/- and wild-type mice.@*Results@#-/- mice developed more severe inflammation and apoptotic responses compared to wild-type mice. Moreover, the NK cell activation was higher in the lungs of -/- mice during acute influenza infection.@*Conclusions@#Based on our results, we speculate that the NK cells are more readily activated in the absence of IFITM3, increasing mortality in -/- mice.

Reverse genetics platform construction of influenza pandemic virus strain / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>Reverse genetics was used to construct the platform of flu pandemic strain A/California/07/2009 (H1N1).</p><p><b>METHODS</b>Eight genes fragements were amplified and ligated with bidirectional vector, recombinant plasmids were co transfected to the 293 T cells and rescued the virus. Gene sequencing, antigenic analysis and growth property were used to evaluate the rescued virus.</p><p><b>RESULTS</b>Rescued virus show the genes sequence correct, keep the same antigenicity and similar growth property compared with wild type virus.</p><p><b>CONCLUSION</b>The pandemic virus reverse genetics platform of A/California/07/2009 (H1N1) were built. Based on this platform, rescued virus hold the similarity of antigenicity and growth ability with wild type virus.</p>

Selection pressure analysis of H3N2 influenza virus from China between 1992 and 2012 / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>In order to investigate the relationship between selection pressure and the prevalence of antigenic clusters, we sequenced and analyzed the H3N2 influenza virus from China between 1992 and 2012.</p><p><b>METHODS</b>The H3N2 influenza virus (n = 1206) in China from 1992 to 2012 was analyzed, include global selection pressure and sites positive selection pressure analysis.</p><p><b>RESULTS</b>Considering all the H3N2 influenza viruses during these 21 years, a total of four amino acid sites subject to positive selection. The global selection pressure varies with the variation of different antigenic clusters and three years with peak bottom selection pressure were identified.</p><p><b>CONCLUSION</b>The global selection pressure rise from the peak bottom, a new antigenic clusters will appear andprevalent in the population, indicating the best time to replace the vaccine strain.</p>

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.

Identification of dual receptor-binding specific strains of human H5N1 viruses in China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>Both the 2, 6 linkage and its topology on target cells are critical for the recognition by human influenza virus. The binding preference of avian flu virus H5N1 HA to the 2, 3-linked sialylated glycans is considered the major factor limiting its efficient infection and transmission in humans. To monitor potential adaptation of H5N1 virus in human population, the surveillance of receptor-binding specificity was undertaken in China.</p><p><b>METHODS</b>The binding specificity of 32 human H5N1 virus strains isolated from 2003 to 2009 was tested by 2, 3-specific sialidase-treated chicken red blood cell (CRBC) agglutination assay and a solid-phase direct binding assay with synthetic sialylglycopolymers.</p><p><b>RESULTS</b>Dual binding preference to 2, 3 and 2, 6-glycans were found in two strains: A/Guangdong/1/06 (A/GD/1/06) and A/Guangxi/1/08 (A/GX/1/08). Though minor effect of short-2, 6-binding was detected in A/GX/1/08 at a low virus titer, both showed high affinity to the oligosaccharide at a high load. Notably both are of the long-2, 6-recognition, with the same topology as that of human H1N1 and H3N2 viruses.</p><p><b>CONCLUSION</b>The findings suggest that human H5N1 virus in China likely acquired the potential human-adaptation ability. Further research and surveillance on receptor-binding specificity of H5N1 viruses are required.</p>

Gene expression profiles comparison between 2009 pandemic and seasonal H1N1 influenza viruses in A549 cells / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To perform gene expression profiles comparison so that to identify and understand the potential differences in pathogenesis between the pandemic and seasonal A (H1N1) influenza viruses.</p><p><b>METHODS</b>A549 cells were infected with A/California/07/09 (H1N1) and A/GuangdongBaoan/51/08 (H1N1) respectively at the same MOI of 2 and collected at 2, 4, 8, and 24 h post infection (p.i.). Gene expression profiles of A549 cells were obtained using the 22 K Human Genome Oligo Array, and differentially expressed genes were analyzed at selected time points.</p><p><b>RESULTS</b>Microarrays results indicated that both of the viruses suppressed host immune response related pathways including cytokine production while pandemic H1N1 virus displayed weaker suppression of host immune response than seasonal H1N1 virus. Observation on similar anti-apoptotic events such as activation of apoptosis inhibitor and down-regulation of key genes of apoptosis pathways in both infections showed that activities of promoting apoptosis were different in later stage of infection.</p><p><b>CONCLUSIONS</b>The immuno-suppression and anti-apoptosis events of pandemic H1N1 virus were similar to those seen by seasonal H1N1 virus. The pandemic H1N1 virus had an ability to inhibit biological pathways associated with cytokine responses, NK activation and macrophage recognition.</p>

Study on the antigenicity and HA1 gene characteristics of influenza A viruses during 2004-2008 year in China / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To under stand influenza A viruses epidemic, antigenicity and genetic characteristics variation between the vaccine and Circulation strains during 2004-2008 year in China.</p><p><b>METHODS</b>The influenza A viruses (H1N1, H3N2) isolated from 2004-2008 year were under took antigenic and sequence analysis. Influenza A virus antigenicity and genetic characteristics were analyzed thought amino acid variation compassion of HA1 protein of influenza A virus isolates.</p><p><b>RESULTS</b>The antigenicity of influenza H1N1 subtype viruses isolated from 2004 to 2007 is very similar with vaccine strain A/New Caledonia/20/1999 (HIN1)-like virus. The influenza H1N1 viruses circulated in 2008 year had similar antigenic characteristics with A/Brisben/59/2007 (H1N1) which is component of influenza vaccines for northern hemisphere 2008-2009 year. The influenza H3N2 subtype viruses of 2004-2005 year had antigenic variation comparatively with vaccine strain A/Fujian/411/12002 (H3N2), The antigenicity of 2006-2007 H3N2 viruses and 2008 year's is A/Wiscansin/67/2006(H3N2) and A/ Brisben/10/2006(H3N2) respectively.</p><p><b>CONCLUSION</b>There is change of influenza A viruses (H1N1, H3N2) antigenic and genetic characteristics during 2004-2008 in China.</p>

The virus isolation analysis of the H5N1 subtype human avain influenza cases in mainland China from 2005 to 2009 / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To analyse the correlation between the virus isolation and the specimen collection of the H5N1 human high pathogenic avain influenza cases in Mainland China.</p><p><b>METHODS</b>The specimens were collected in Mainland China from 2005.10 to 2009.3 and the H5N1 viruses were isolated by passage in embryonated chicken eggs.</p><p><b>RESULTS</b>Most specimens were obtained within 14 days after disease onset. For the specimens collected within 7 days, the isolation rate was relatively high and the difference of the positive rate between different years was lower than those specimens collected after 7 days. Most of the samples in our study were collected from the upper or lower respiratory tract with few from blood, feces, et al. The isolation rate of lower respiratory specimens was higher and the difference of the positive rate between different years was relatively lower than those from upper respiratory specimens.</p><p><b>CONCLUSION</b>We suggest that the samples should be collected from lower respiratory tract during the acute phase to get the higher isolation rate.</p>

Establishment of a method for rapid detection of the nucleic acid of the novel A (H1N1) influenza virus / 病毒学报

A new flu caused by a novel influenza A(H1N1) virus has spread over the United States, Mexico and more than 40 other countries. And because of the immediate global concern, WHO has announced that the current level of influenza pandemic alert is raised to phase 5, indicating approaching of an influenza pandemic. As patients suffering from the influenza A (H1N1) have the similar symptoms as patients with seasonal influenza, differential detection and identification of the influenza virus have to depend on specific laboratory tests. We have successfully developed a RT-PCR based method for detection of the influenza A (H1N1) virus, and had applied the method to detection of clinical samples.

Laboratory confirmation of the first influenza A (H1N1) imported case in Mainland China / 病毒学报

The clinical throat swab specimen of an imported suspected case of influenza A (H1N1) was detec ted with real-time PCR, RT-PCR and subsequently confirmed by gene sequencing. The presence of influ enza A (H1N1) virus confirmed the first case with A (H1N1) infection in Mainland China.

Antigenic and genetic study of influenza virus circulated in China in 2006 / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To analyse seasonal influenza epidemic situation in 2006, and to analyse the genetic and antigenic characteristics of viral hemagglutinin (HA) gene.</p><p><b>METHODS</b>The single-way hemagglutination inhibition (HI) tests were used to test the antigenic characteristics of these viruses from influenza surveillance network, and the HA1 genes were sequenced based on the antigenic test results according to different isolation times and sites.</p><p><b>RESULTS</b>The influenza virus types A and B co-circulated in 2006. influenza A H1N1 subtype and Victoria-like B influenza circulated preponderantly during this epidemic season. The HA1 gene sequence of H1N1 viruses showed that 192, 193, 196, 198 positions (located at antigenic site B) have an amino acid substitute, compared with the last circulating strain A/Hubeihongshan/53/2005(H1N1). Two amino acid changes at 142 and 144 positions compared with A/Yunnan/1145/2005 (H3N2). There was no change in influenza B viruses either Victoria-like B or Yamagata-like B virus, i.e . antigenic characteristics is analogous to B/shenzhen/155/2005 and B/tianjin/144/2005, respectively.</p><p><b>CONCLUSION</b>The H1N1 and H3N2 influenza viruses had changing antigenic and genetic characteristics in 2006. Influenza virus types B did not change in 2006.</p>

Study on the correlation of human influenza A/H3N2 hemagglutinin gene variation and the epidemic from 1995 to 2005 in China / 病毒学报

To study the correlation of human influenza A/H3N2 hemagglutinin gene variation and the epidemic from 1995 to 2005 in China, 550 HA1 sequences of H3N2 viruses isolated in China were analyzed with phylogenetic tree. The results showed that the evolution of HA1 represented a long trunk with short side branches. The animo acid changes of HA1 mostly located at the antigenic sites or aside of them, but also may occur at the other sites simultaneously. The analysis also showed three possibilities of HA1 variation to cause H3N2 epidemic, the first is multiple site mutations happened simultaneously; the second is mutation sites happened gradually and then accumulated to multiple sites; the third is a single antigenic site mutation occurred simultaneously with the receptor binding site variation.

Characteristic analysis of NA gene of human influenza viruses (H3N2) isolated from 1996 to 2005 in China / 病毒学报

The NA genes of 395 strains of human H3N2 influenza virus isolated from 1996 to 2005 in China were sequenced, analyzed with bioinformatics tools. The NA nucleotide sequence of phylogenetic tree showed a main evolution branch with multiple short side branches. The strains in the same year may be divided into several branches. There was an obvious lag between vaccine strains recommended by WHO and the Chinese circulating strains in phylogenetic tree of the NA nucleotide. The result also showed no amino acid deletion and insertion in the NA. In NA antigen sites, where including residues 197-199 aa, 431-434 aa and 339-347aa the mutation was higher, in contrast, the residues including 153 aa, 328-336 aa, 367-370aa and 400-403 aa, the mutation was lower. Besides the antigenic determinant sites, there also had the other amino acid mutated highly, such as 18, 23, 30, 93, 143, 208, 216, 221, 249, 265, 267, 307, 385 and 437 aa, among them 143 and 267 mutation were higher than that in antigenic determinant sites, their biological significance are not clear yet. The neuraminidase active-site residues in NA were highly conservative and the same were the disulphide bond and the glycosylation sites in NA. In conclusion, our analysis provides some information for influenza prevention and control and the NA inhibitor medicine application.

Evolutionary characterization of HA1 of influenza H1N1 hemagglutinin gene surveyed in 1981-2005 in China / 病毒学报

To understand the evolutionary characterization of HA1 of H1N1 influenza virus HA gene circulaing from 1981 to 2005 in China, viral RNAs of 370 H1N1 strains were extracted and transcribed into cDNA by reverse transcriptase and amplified by PCR. The products of PCR were sequenced. The sequences were analyzed through biometic software. The results showed that all the four antigenic sites were mutated, bigger change occurred on the Sb and Ca sites; the 130 loop of receptor binding sites(RBS) of HA1 amino acid deleted at the 134th site in 1991 firstly, then the number of the deleted strains were increasing, since 2000, all the strains had deleted at the 134th site, and simultaneously, the amino acid at 137th site was substituted by S for T. The change of HA1 glycosylation sites was found and 7 sites kept stable from 2000 to 2005. The H1N1 strains of the same year almost clustered in the same group on the phylogenetic tree and were irrelevant to virus isolated time and area. There appeared two groups of 2005 H1N1 virus strains that differed in time of virus isolation.

Application of single radial hemolysis technique for diagnosis of influenza A (H5N1) / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To understand the optimal condition of single radial hemolysis (SRH) for diagnosis of avian influenza A (H5N1) virus in order that SRH could be performed in general laboratories.</p><p><b>METHODS</b>The effect of different concentration of virus and species of red blood cells, as well as kind and concentration of agarose on testing sensitivity of SRH was determined. Meanwhile the sensitivity and specificity of this method were compared with those of micro-neutralization test.</p><p><b>RESULTS</b>The optimal condition of SRH included the viral concentration of 1000 HA units per 0.1 ml packed chicken red blood cells, the agarose concentration of 1.0%, the compliment added into agarose-virus-rbc slides after diffusion of sera. The sensitivity and specificity of SRH were very similar to those of micro-neutralization test. Meanwhile, no cross reaction between antibodies, especially antibodies against N1 antigens, H5N1 and H1N1 viruses was detected.</p><p><b>CONCLUSION</b>The sensitivity and specificity of SRH were very similar to those of micro-neutralization assay. SRH could be performed in normal laboratories and be used for testing large scale serum samples.</p>

Antigenic and genetic study of influenza virus B circulated in China in 2004-2005 / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To analyze the genetic and antigenic characteristics of hemagglutinin (HA) gene of human influenza B virus isolated from the mainland of China since 2004-2005.</p><p><b>METHODS</b>The single-way hemagglutinin inhibition (HI) tests were used to test the antigenic characteristics, and the HA1 gene was sequenced based on the antigenic results.</p><p><b>RESULTS</b>The Yamagata-like and Victoria-like viruses co-circulated in 2004-2005. For the Yamagata-like virus, the single-way HI results showed that 3.7% and 4.5% of the viruses had 4-fold greater HI titer difference compared with B/Shanghai/361/02 in 2004 and 2005, respectively. The HA1 sequence data showed that the virus had amino acid mutation, and there was one more glycosylation site at 196th site. For the Victoria-like virus, the single-way HI results showed that 8.5% and 20.6% of the viruses had 4-fold greater HI titer difference compared with B/Hong kong/330/01 in 2004 and 2005, respectively. The HA1 sequence data showed that the virus had replacement of 9 amino acids, and there was one more glycosylation site at 197th site.</p><p><b>CONCLUSION</b>The results showed that influenza B viruses had changed antigenic and genetic characteristics compared with B/Shanghai/361/02, B/Hong kong/330/01 in 2004-2005.</p>

Antigenic and genetic study of influenza virus (H1N1) circulated in China in 2004-2005 / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To analyze the genetic and antigenic characteristics of hemagglutinin (HA) gene of human influenza (H1N1) virus isolated from the mainland of China since 2004 to 2005.</p><p><b>METHODS</b>The single-way hemagglutination inhibition (HI) tests were used to test the antigenic characteristics, and the HA1 gene was sequenced based on the antigenic results.</p><p><b>RESULTS</b>The single-way HI results showed that no virus isolates had 4-folds greater HI titer compared with A/Shanghai/1/1999 (H1N1) in 2004, but there was 6.3% virus had 4-fold greater difference in 2005. The HA1 sequence data showed that the H1N1 virus had the following amino acid mutations such as 54 K > R, 90 T > K, 101 Y > H, 149 R > K, 169 V > A, 190 D > N, 212 R > K, 219 K > R, 245 W > R, 246 Y > F, 258 T > N, 318 V > A and the 54 and 190 amino acids located in antigenic group of HA1.</p><p><b>CONCLUSION</b>The H1N1 virus was changing in antigenic and genetic characteristics.</p>