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Objective To reveal evolution characteristics and antigenic epitope variabilities of hemagglutinin (HA) gene of H3N2 viruses in Guangdong during 2014-2015.Methods The HA gene nucleotide sequence of influenza H3N2 virus isolated during 2014-2015 in Guangdong Province was selected by spatial-temporal distribution.The HA gene nucleotide sequences were compared with global HA genes downloaded from GenBank and GISAID and the gene nucleotide mutations were analyzed.The phylogenetic tree and the entropy chart were conducted.Results Compared with HA gene of vaccine strain A/Texas/50/2012,the substitutions of 25 amino acid sites occurred in the HA gene of the 17 Guangdong strains during 2014 to 2015.The epitope A,B,D and E of the HA1 gene developed mutations,which involved 11 amino acid sites.One glycosylation site deletion occurred in A/Guangdong/ 55/2015 in virtue of the N38K site mutation.The high mutation site was at 175 with entropy value of 1.16.The 363 site might be the positive selection while the 368 and 425 sites might be the negative selection sites by comprehensive evaluation of the screening results of the single likelihood ancestor countincy (SLAC),fixed effects likelihood (FEL) and internal fixed-effects likelihood (IFEL) model.Conclusions The mutations emerge in the epitopes A,B,D and E of HA gene of the Guangdong H3N2 stains.Evolution at 363 site is positive selection while those at 368 and 425 sites are negative selection.The mutation accumulation might lead to the epidemic of influenza H3N2.
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Objective To detect the positive rates of antibodies against avian influenza virus (AIV) subtypes H5, H6, H7 and H9 among people in poultry occupations in Guangdong province and to analyze the transmission of various subtypes of AIV from poultry to human contacts for the prevention and control of novel AIV infection in human beings.Methods Serum specimens were collected from 1066 peo-ple in poultry occupations ( occupational group) and 205 people not in poultry occupations ( non-occupational group) in 10 cities of Guangdong province.The inactivated AIV strains, isolated from poultry or environment of Guangdong province, were used as antigens to detect antibodies against AIV subtypes H5, H6, H7 and H9 by using the hemagglutination inhibition ( HI) assay.Results The positive rates of antibodies against AIV subtypes H5, H6, H7 and H9 carried by people from the occupational group were respectively 0.44%, 0%, 0.30%and 0.30%in 2013 and 1.08%, 0.0%, 0.0%and 0.27%in 2014.Only the anti-H9 anti-bodies were detected in serum samples collected form people in the non-occupational group in 2013 with a positive rate of 0.95%.No significant differences with the positive rates of anti-AIV antibodies were found between the occupational group and the non-occupational group.However, the geometric mean titer ( GMT) of anti-AVI antibodies in people from the occupational group was higher than that of the non-occupational group.Conclusion Although a grand spread of AIV from avian to human is not likely to happen yet, con-tacting with poultry is the risk factor for AIV infection in Guangdong population.A long-term surveillance of anti-AIV antibodies in serum should be strengthened among people in poultry occupations for the timely pre-vention and control of novel AIV outbreak.
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Objective To investigate the susceptibility to oseltamivir of influenza pandemic A (H1N1) 2009 viruses in Guangdong province during 2009,provide valuable information of prescription for clinics,and elucidate the variant trend of the epidemic strain based on phylogenetic analysis.Methods During April to December 2009,clinical specimens were collected from sentinel hospitals covering the whole Guangdong province.Virus isolation was performed by in MDCK cells or embryonated chicken eggs.A fluorescence-based neuraminidase (NA) enzyme inhibition assay was conducted to measure influenza susceptibility.The NAI susceptibility of influenza virus was expressed as the concentration of NAI needed to inhibit the NA enzyme activity by 50％.A subset of 68 viruses were performed NA sequencing for detecting resistant mutations and studying variant trends.Results During surveillance,221 influenza pandemic A ( H1N1 ) viruses were isolated.All strains were sensitive to oseltamivir inhibition assay,with a median IC50 of 0.24 nmol/L (range 0.02 -1.66 nmol/L).No mutation related to resistance was found.Phylogenic analysis illustrated that these NA genes were homology high to 99.5％ - 100.0％ with those from other countries.Conclusions influenza pandemic A (H1N1) 2009 viruses were sensitive to oseltamivir in Guangdong,and useful for prophylaxis and treatment of influenza infection.Little selective pressure was found by phylogenic analysis.Our laboratory will continue to observe antiviral-resistance among circulating influenza viruses.
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Objective To understand the evolutionary characterization of hemagglutinin (HA)gene of pandemic H1N1 influenza virus in Guangdong during 2009-2011. MethodsWe selected 83 pandemic H1N1 strains isolated in Guangdong during 2009-2011. The HA1 genes were sequenced and analyzed comparatively by Bioedit 7.0 and MEGA 4.0. ResultsThe evolutionary rate of Hal gene of pandemic H1N1 and seasonal H1N1 viruses was 5.2×10-3 substitutions/site/year, higher than that of seasonal H1N1 viruses. Most amino acid changes in HA1 molecules accumulated on the surface of the molecule and were partly located in antigenic sites. Two fatal infections were detected with a mutation at HA residue 222, in one virus with a change D222G, and in one virus D222N. ConclusionThe phylogenetic analysis demonstrates that the influenza epidemic in Guangdong at the beginning of 2011 are due to occurrence of genetic changes of pandemic H1N1 virus. The amino acid change at residue 222 of the HA1 are likely to be associated with severe or even fatal illness.
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Objective To analyze the genetic characterization(evolution, antigenicity, enzyme activity sites and glycosylation sites)of the neuraminidase(NA)gene of the novel influenza virus A/H1N1 in 2009 pandemic in Guangdong Province. Methods The viral RNA was extracted from 69 isolates of influenza virus A/H1N1 from patients in 2009 pandemic in Guangdong Province. NA gene fragments were amplified by reverse transcription polymerase chain reaction (RT-PCR) and sequenced. The other 52 NA gene sequences of influenza virus A in different years and different regions were retrieved from GenBank. The analysis of evolution and amino acid sequences were analyzed by MEGA 4.0 software. Results The homology of 2009 novel H1N1 influenza viruses in Guangdong and avian H5N1 influenza virus strains was high(＞85 % ). The amino acid distributions of potential antigenic sites were identical. The enzyme activity sites of NA genes of all virus strains were strictly conserved, which had eight glycosylation sites. But there were amino acid substitutions in 5 glycosylation sites, while it was identical with the 2001 avian H5N1 influenza virus. Conclusion The NA genes of 2009 novel H1N1 influenza viruses in Guangdong are high homologous with avian H5N1 influenza virus and the viral specific binding sites of neuraminidase inhibitor are not changed.