An analysis on epidemiological characteristics of Japanese encephalitis in Zhejiang Province / 预防医学

Objective To analyze the epidemiological characteristics of Japanese encephalitis (JE) in Zhejiang Province from 2007 to 2016 for developing the measures of control and prevention. Methods The data were collected from national notifiable diseases registry system (NNDRS) and case-based JE surveillance system (JESS) from 2007 to 2016, and they were analyzed through descriptive epidemiological method and Microsoft Office Excel 2010. Results From 2007 to 2016, a total of 595 JE cases were reported in Zhejiang Province, with an average annual incidence of 0.114 per 100000 population, among which, 559 (93.95%) were laboratory confirmed. During the ten years, 20 cases died and the average annual case fatality rate was 3.36% . Cases were distributed mainly in Wenzhou, Ningbo and Taizhou Cities, which accounting for 54.79% of the total.The peak months were July, accounting for 86.89% of all the cases.And 85.71% of all the cases were in the age of 0-14 years and 47.73% were scattered children.And 22.77% of the JE cases were vaccinated but 14.01% of them did not complete the whole course.And 77.23% of the cases did not have the experience of vaccination or unknown.Conclusion The incidence of JE is decreasing. The occurrence of JE is sporadic with distinct seasonal peak and mainly concentrating in young-age children.

A study on the development of a triplex real -time RT -PCR for simultaneous detection of enteroviruses and differentiation of EV 71 and CA 16 / 预防医学

Objective To develop a multiplex real -time RT -PCR assay for simultaneous detection of enteroviruses and differentiation of EV71 and CA16.Methods Specific primers and probes were designed for enteroviruses,EV71 and CA16.The probes labeled with various fluorescent reporter dyes,and a triplex real -time RT -PCR technique was developed to simultaneously detect these viruses.A total of 91 clinical specimens with suspected HFMD were analyzed by this method.Results This assay could simultaneously detect enterovirus and differentiation of EV71 and CA16,and the sensitivity of the assay was up to 0.1 TCID50 /mL,and only need 2 to 3 hours for completing the detection.A total of 91 clinical specimens were detected by this assay in 28 of the 91(30.77%)specimens contained EV71,9 of the 91(9.89%) contained CA16,and 5 of the 91 (5.49%)contained other enteroviruses.Conclusion This assay would be a useful molecular diagnostic tool for large -scale screening of clinical samples,especially at the peroid of HFMD outbreaks.

Etiological and molecular-epidemiological analysis on enterovirus associated encephalitis in Zhejiang, 2008-2012 / 中华流行病学杂志

Objective In order to investigate etiology and molecular-epidemiological characteristics of enterovirus associated encephalitis (EAE) in Zhejiang,2008-2012.Method Cerebrospinal fluid and stool specimens were collected from suspected EAE patients,who were admitted to our hospitals.RD and Hep-2 cell lines were used to isolate enterovirus (EV).Serotypes of these EV isolates were identified through neutralization test by using serotype specific anti-sera.VP 1 genes of these isolates were sequenced,compared and used for the construction of phylogenetic tree.Results 127 (20.6％) human enterovirus (HEV) strains were isolated from 616 samples,which were collected from 610 patients.Serotypes of these EV isolates,including 60 coxsackievirus (CV),and 67 Echovirus (E) appeared to be CVA9,CVB1,CVB3-5,E3,E4,E6,E9,El4,E25 and E30,respectively.Predominant EV serotypes on EAE from 2008 to 2012 were seen as CVB3,CVB5,E6,E30 and E30,respectively.The full length of VP1 genes from different EV isolates was between 834 and 918 nucleotides.The VP1 gene similarities between these isolates and the reference strains were from 76.7％ to 85.0％ (nucleotides level) and 91.1％ to 97.9％ (amino acids level).The VP1 genes from E6 serotype isolates appeared most diverged,reaching 20.4％ (nucleotides level) attd 4.8％ (amino acids level).Based on the generated phylogenetic tree,all the EV isolates were fallen on the same branch of HEV-B,and the isolates in the same serotype formed one sub-branch,suggesting there existed geographical and temporal effects.E6 isolates diverged into two branchlets.Conclusion EVs from HEV-B were the etiologic agents for EAE in Zhejiang province from 2008 to 2012.All these EV isolates showed 12 serotypes,with predominant isolates varied every year.E30 was determined as the most dominant serotype while serotype E6 diverged into two sub-genetypes.

Study on the complete sequence of CA24 variant isolated during the acute hemorrhagic conjunctivitis outbreaks in Zhejiang province during 2002 to 2010 / 中华流行病学杂志

Objective To analyze the genetic characteristics of the complete sequence of coxsackievirus A24 variant(CA24v) isolated from acute hemorrhagic conjunctivitis (AHC) outbreaks in Zhejiang province during 2002 to 2010.Methods Complete sequences of CA24v epidemic strains isolated in different years were amplified under the RT-PCR assay,while the sequences of whole genome,VP1,and 3C region of Zhejiang strains were compared with epidemic strains isolated in other areas of China and abroad.Results The whole genome of Zhejiang CA24v strains isolated in 2002 and 2010 was 7456-7458 bp in length,encoding a polyglutamine protein which containing 2214 amino acid residues.There was a insertion with T on site 97 and 119 within 5' non-coding region between epidemic strain Zhejiang/08/10 and strains isolated in 2002.The rates of amino acid homology among Zhejiang/08/10 and other strains isolated since 2002 were between 94.7％ and 100.0％.Compared with the representative strains circulated within the recent 60 years,the largest average amino acid variations had been occurred on region 2A and 3A,with the ratios as 8.4％ and 7.3％ respectively.The smallest variation happened in region 3D,with the ratio only as 1.9％.The rates of stable amino acid variation on the whole genome between strains isolated since 1987 and 2002 were 38 and 20.P-distance within groups appeared that region 3C was more stable than VP1 of strains isolated in 2002-2010,and the 3D of early strain Jamaica/10628/87 might have had a nature of recombination but not observed on those epidemic strains in recent years.Conclusion Within the evolution of CA24v strains,the time course was more significant than the geographical differences.There had been sporadic epidemics of AHC caused by CA24v in Zhejiang province since 2002.

Genomic sequences of human infection of avian-origin influenza A(H7N9)virus in Zhejiang province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the etiology and genomic sequences of human infection of avian-origin influenza A(H7N9)virus from Zhejiang province.</p><p><b>METHODS</b>Viral RNA was extracted from patients of suspected H7N9 influenza virus infection and real-time RT-PCR was conducted for detection of viral RNA. All 8 segments of influenza virus were amplified by one-step RT-PCR and genomic sequences were assembled using the sequencing data. All the currently available HA and NA genes of the novel H7N9 virus, some other HAs from H7 subtype and NAs from N9 subtype were downloaded from public database for phylogenetic analysis, using the Mega 5.1 software. Mutations and variations were analyzed, using the genomic sequence data.</p><p><b>RESULTS</b>Reactions for influenza type A, subtype H7 and subtype N9 were all positive and all the genomic fragments were amplified for sequencing. After alignment, sequences were subjected for phylogenetic analysis. The results revealed highest homology with A/duck/Zhejiang/12/2011(H7N3)in HA gene and with A/wild bird/Korea/ A14/2011(H7N9)in NA gene of the H7N9 influenza virus. All 6 genes coding for internal proteins shared highest identities with H9N2 avian influenza which were circulated in the Chinese mainland, in the last two years. The sequenced virus showed Q226L mutation in HA protein, but E627K was not presented in PB2 protein of this virus. The E627K mutation was shared by all the other novel H7N9 viruses resulted in human infections through analysis on the currently available sequences.</p><p><b>CONCLUSION</b>Using the clinical samples, both detection of the viral genes and amplification of all 8 segments of the novel H7N9 influenza virus were accomplished. High homology of the novel H7N9 influenza viruses was observed by phylogenetic test, using the currently available sequences. The virus showed Q226L mutation on HA protein but E627K did not present on PB2 protein of this virus.</p>

Identification of genotype III Japanese encephalitis virus isolated in Zhejiang province / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the molecular characteristics and genotype of Japanese encephalitis virus (JEV) found in vector mosquitoes in Zhejiang province from 1982 to 1983.</p><p><b>METHODS</b>A total of 3188 mosquitoes were collected in Dinghai district and Yiwu city in Zhejiang province, during year 1982 and 1983. The virus was isolated by C6/36 cell, and then identified by hemagglutination inhibition test. The isolated strains were activated in year 2011, and plaque forming unit (PFU) were applied to test the virus titer. The suckling rats were tested under intracranial inoculation, where PrM and E genes were amplified and sequenced. Their nucleotide and amino acid sequences were analyzed and compared with the JEV vaccine strain SA14-14-2 and the JEV isolated in Zhejiang province during 2007 and 2010; and phylogenetic tree were constructed by bioinformatic software.</p><p><b>RESULTS</b>From the 3188 mosquitoes captured, eleven virus strains were isolated and found to be able to cause cytopathogenic effect (CPE) in C6/36 cells within 72 hours. Virus titer ranged from 2.5 to 6.47 lg PFU/ml. The suckling rats would die within 72 hours since the inoculation. The phylogenetic analysis with the PrM and E genes showed that the JEV isolated in Zhejiang during 1982 and 1983 belonged to genotype III; while the JEV isolated in Zhejiang during 2007 and 2010 belonged to genotype I. The analysis of E genes from 5 isolated strains found that the homology of nucleotide sequence was over 98.9%, and the homology of amino acid sequence was over 99.8%. The compare between the 5 virus strains and the vaccine strain SA14-14-2 found 10 common amino acid variation sites, and showed that the homology of nucleotide sequence was over 97.7%, and the homology of amino acid sequence was 99.2%. The compare between the 5 virus strains and the JEV isolated in Zhejiang during 2007 and 2010 found a 87.7% - 87.9% nucleotide homology and an over 98.8% amino acid homology.</p><p><b>CONCLUSION</b>The JEV isolated from the mosquitoes in Dinghai district and Yiwu city between year 1982 and 1983, were genotype III.</p>

Study on the molecular characteristics of Japanese encephalitis virus living in vector mosquitoes, in Zhejiang province, 2009-2010 / 中华流行病学杂志

Objective To investigate the molecular characteristics of Japanese encephalitis virus (JEV) living in vector mosquitoes,from Zhejiang province.Methods A total of 13620 mosquitoes were collected from the monitoring stations located in Cixi city and Xianju county in Zhejiang province,in July and August,2009-2010.Nucleic acid of JEV from the mosquitoes was monitored by using real-time RT-PCR.The virus strains were isolated with BHK-21 cell line,with E genes of the isolated viruses amplified,sequenced and their phylogeny and homology analyzed.Results The positive rates of JEV for those mosquitoes collected in the stations of Cixi and Xianju were 17.0％ (27/159) and 3.4％ ( 1/29 ),respectively.Twenty-two JEV strains were isolated,accounted for 15.4％ among the 143 batches of mosquitoes collected in 2010.All E genes in the 6 sequenced virus isolates contained 1500 nucleotides encoding 500 amino acids,in which no inserts and deletions were identified.The identity rates of nucleotide and amino acid in E gene were 99.2％-99.8％ and 100.0％ among the 6 JEV strains isolated from Zhejiang,99.1％-99.3％ and 99.2％-99.8％ between the Zhejiang strains in 2009-2010 and the Zhejiang strains in 2007-2008,respectively,87.6％-88.0％ and 97.8％ between the 6 Zhejiang strains and the vaccine strain SA 14-14-2 of JEV,respectively.The phylogeny tree of E gene indicated that the JEV isolates in Zhejiang during 2009-2010 was located in the branch of the genotype Ⅰ.Conclusion Mosquitoes collected from Cixi and Xianju areas carried JEV,with the rate of JEV in Cixi higher than in Xianju.All the Zhejiang isolates in 2009-2010 were proven to be the genotype Ⅰ of JEV.

Study on the etiological and molecular characteristics of aseptic meningitis epidemic in Zhejiang Province in 2002-2004 / 病毒学报

In order to confirm the cause of the outbreak of aseptic meningitis in Zhejiang Province in 2002-2004, trace the pathogen and analyze the molecular characteristics, 271 cerebrospinal fluid (CSF) and faeces specimens were collected from suspected patients. The virus strains from the specimens were isolated with RD and Hep-2 cell lines. The VP1 and VP4/VP2 genes of the isolated viruses were sequenced, and their phylogenetic and homology trees were also constructed. Of the total 271 samples, 78 Echovirus type 30 (E30) strains were isolated. All of the complete VP1 genes in 31 sequenced virus isolates of E30 were composed of 876 nt without any insertion or deletion, encoding 292 amino acids (aa). The identity of nucleotide and amino acid in VP1 gene were 84.7%-86.3% and 92.1%-94.2% between the 31 Zhejiang strains and the prototype strain Bastianni of E30, and 87.1%-99.4% and 96.2%-100% among the 31 Zhejiang strains, respectively. The Zhejiang strains of E30 in the phylogenetic tree of the VP1 gene were attributed into two branches of the G and H genotype, respectively. In G genotype, the Shangdong and Jiangsu E30 strains in 2003 among domestic strains and Ukraine E30 strain in 1999 among overseas strains had maximum similarity with the Zhejiang strains, while H genotype had maximum similarity with the Korea E30 strains in 2008. The phylogenetic tree of the VP4/VP2 genes was similar to that of VP1 gene. The results indicated that the outbreak of aseptic meningitis in Zhejiang Provinec in 2002-2004 was caused by the G and H genotypes of E30 strains existing simultaneously. The H genotype was a new variant strain, which was first isolated in Zhejiang Province in 2002.

Study on the pathological and molecular characteristics of AHC epidemic in Zhejiang Province in 2010 / 病毒学报

To identify and trace the pathogen of acute hemorrhagic conjunctivitis (AHC) epidemic in Zhejiang Province in 2010. Viral nucleic acid of Enterovirus (EV) and Coxsackievirus A24 variant (CA24v) were directly detected by real-time RT-PCR from the conjunctival swab collected from suspected patients. The virus was isolated from the swab samples using Hep-2 cell. The viral RNAs were extracted from the isolated viruses and followed by RT-PCR to amplify VP1 gene and 3C protease region(3C). The amplified fragments were sequenced and phylogenetic trees were also constructed. Eight out of 13 swab samples from suspected patients were both positive for EV and CA24v RNA (61.5%), 6 CA24v strains were isolated (46.2%). The complete VP1 genes of CA24v in 4 sequenced virus strains were 915 nt in length and the complete 3C genes were 549 nt in length. All VP1 and 3C genes were confirmed without any insertion or deletion. The identity of nucleotide and amino acid in 3C between the 2010 isolated strains and the prototype strain EH24/70 were 85.2%-85.8% and 96.2%-96.7%, and that between the 2010 Zhejiang strains and the Zhejiang,Yunnan and Guangdong CA24v strains isolated between 2007-2008 were 93.4%-93.8% and 96.7%-97.3%, respectively. The phylogenetic tree of 3C indicated that the isolated CA24v viruses of Zhejiang in 2010 located in the CA24v IV genotype cluster 4 (GIV-C4) and all the VP1 genes located in the human Enterovirus C (EV-C) CA24v. These findings indicated that AHC epidemic in Zhejiang Province in 2010 was caused by CA24v GIV-C4 viruses and they most likely evolved from CA24v viruses circulating locally in external environment from 2002.

Study on the pathological and molecular characteristics of viral meningitis outbreaks in Linhai county, Zhejiang province, 2004 / 中华流行病学杂志

Objective In order to confirm the causes of viral meningitis outbreaks in Linhai county,Zhejiang province in 2004,and to analyze the relationship between hereditary variation and evolution of the pathogen.Methods 60 cerebrospinal fluid(CSF)specimens were collected from the suspected patients.Virus strains from the specimens were isolated with RD and Hep-2 cell lines,and identified through neutralization test.VP1 and VP4/VP2 genes of the isolated viruses were sequenced.Both phylogcnetic and homological trees were also constructed.Results 19 Echovirus type 30(E30)strains were isolated from 60 CSFs,in which E30 accounted for 31.7％.All of the complete VP1 genes in 4 sequenced virus isolates of E30 were composed of 876 nt,encoding 292 amino acids(aa).The identity of nucleotide and amino acid in VP1 gene were 82.4％-84.1％ and 93.5％-94.2％ between the 4 Linhai strains and the prototype strain Bastianni of E30,were 87.1％-99.9％ and 97.9％-100.0％ among the 4 virus strains of E30 from Linhai,respectively.The 4 Linhai strains could be classified into two classes.The diversity of nt and aa was minimal in the same class but obvious between the two classes,with the range of diversities as 12.9％ and 2.1％,respectively.The Linhai E30 strains had maximum similarity with the Zhejiang E30 strains in 2002-2003.The 4 Linhai strains of E30 in the phylogenetic tree of the VP1 gene were attributed into two branches of the G and H genotype,respectively.The G branch also included the E30 strains from Zhejiang,Jiangsu and Shangdong in 2003,while the H branch including E30 strains from Zhuji,Zhejiang in 2002.The phylogenetic tree of VP4/VP2 genes was similar to that of VP1 gene.Conclusion The outbreak of viral meningitis in Linhai county in 2004 was caused by the two classes of E30 strains with G and H genotype existed simultaneously.The Linhai E30 strains had maximum genetic relations to the Zhejiang,Jiangsu and Shangdong strains of E30.The H genotype was inferred to be a new variant strain,which was first isolated in Zhejiang province in 2002.

Genetic variation of the hemagglutinin and neuraminidase of influenza B viruses isolated in Zhejiang province during 1999-2010 / 中华流行病学杂志

Objective To Characterize the genetic diversity of hemagglutinin(HA)and neuraminidase(NA)of influenza B viruses isolated in Zhejiang province during 1999-2010.Methods Respiratory specimens were collected from patients with flu-like syndrome during the influenza outbreaks or from the hospitals which carrying out influenza surveillance project in Zhejiang province.Samples were detected by real-time RT-PCR and isolated for influenza virus.HA1 and NA genes of influenza B virus isolates were amplified and sequenced.Phylogenetic comparison and genetic diversity analysis were performed using the bioinformation software.Results A total of 34 influenza B viruses were evolved in this study including Victoria-like and Yamagata-like strains according to the results of the HI test.The mutation rate of Victoria-like HA1 gene was 4.5% and Yamagata-like HA1 gene was 3.4%,respectively.The Victoria-like influenza B isolates had appeared to be all re-assortants having a Victoria lincage HA and Yamagata lineage NA since 2004.The predominant type of influenza virus isolates in 2010 was also influenza B virus after the H1N1 flu pandemic in Zhejiang province.The isolated strains were antigenicaily and genetically similar to B/Brisbane/60/2008--the vaccine strain proposed for 2009-2010.Many difierences of HA1 and NA amino acids existed in the current isolates when compared to previous influenza B strains.Conclusion Significant diversity was generated among influcnza B virus isolated from 1999 to 2010 in Zhejiang province.Genetic re-assortment and antigenic drift seemed the main evolutionary mechanism on influenza B virus.

Diagnosis of a dengue fever outbreak in Yiwu city, Zhejiang province in 2009 and its molecular tracing of the pathogen / 中华预防医学杂志

<p><b>OBJECTIVE</b>To determine a dengue fever outbreak in Yiwu city, Zhejiang Province in 2009 and to trace the origin of the pathogen.</p><p><b>METHODS</b>The dengue virus IgM, IgG antibodies and viral nucleic acid were detected and virus was isolated using 40 serum samples from the suspected patients. The viral RNA of the isolated virus strains was extracted and the E gene was amplified by RT-PCR. The amplicons were sequenced and the phylogenetic and homological analyses were also constructed.</p><p><b>RESULTS</b>Among 40 serum samples from dengue fever suspected patients, 17 were positive from for dengue IgM (42.5%); 4 were IgG positive (10.0%); 34 samples were dengue virus RNA positive (85.0%), 28 dengue virus type 3 (D3) strains were isolated (70.0%). The complete coding region of envelope genes (E) from 13 D3 strains was all 1479 nt without any insertion or deletion, which encoded with 493 amino acids (aa). E gene from the 13 D3 strains from Zhejiang in 2009 (D3/ZJ/2009) was 100.0% identical. The strain from Saudi Arabia shared the highest similarity with the D3 strain, 99.3% and 100.0% of their E genes and deduced amino acids were identical, respectively, whereas they were 93.4% and 97.4% between D3/ZJ/2009 strain and its prototype strain (D3/H87/1956), and 93.6% and 97.4% between D3/ZJ/2009 and a D3 strain isolated in Guangxi Province in 1980. The phylogenetic tree of E genes also indicated that D3/ZJ/2009 had maximum similarity with the D3/Saudi Arabia/2004. They all belonged to the D3/GIII branch, which was originated from Indian Subcontinent.</p><p><b>CONCLUSION</b>The outbreak of dengue fever in Zhejiang in 2009 was caused by type 3 dengue virus III genotype. The virus was most likely originated from Saudi Arabia.</p>

Traceability of the A/H3N2 virus borne influenza pandemic in Zhejiang province,1998 / 中华流行病学杂志

Objective To trace back to the influenza pandemic caused by A/H3N2 virus happened in Zhejiang province,1998.Methods The whole genome of three isolates related to Zhejiang influenza virus was amplified through RT-PCR,and the identified sequences were aligned with the sequences downloaded from GenBank of the H3N2 strains which were circulating in other regions during 1995 to 1998.The crossing HAI titers of the reference strains were measured by HAI test and antigenic ratios were calculated.Results The Phylogenetic tree,constructed based on HA sequence showed that the dominant strains A/Zhejiang/11/98 and A/Zhejiang/18/98 were significant different from the isolates circulated in other regions during 1995 to 1996 and the strains isolated in the mainland of China,in 1997.Although the A/Zhejiang/11/98 and A/Zhejiang/18/98 strains were distributed in the same cluster with A/Sydney/5/97,the two strains were closer to the epidemic strains isolated in Hong Kong and New York in the later part of 1997.Based on HAI,NA and MP genes,A/Zhejiang/18/98 seemed to be the closest one to the Hong Kong epidemic strains,and the genetic distances between A/Zhejiang/18/98 and New York strains were shorter than that with A/Sydney/5/97 based on PA,HA and NS genes.There were only 1-3 amino acid differences between A/Zhejiang/18/98 and Hong Kong or New York strains,whereas 7 amino acid differences with A/Sydney/5/97,in which three were located in the antigenic determinant regions.Data from the crossing HAI test showed that the antigenic ratio between A/Zhejiang/18/98 and A/Sydney/5/97 had reached 2.0,indicating the antigenic difference to a certain extent.Additionally,the onset of the influenza epidemic during 1997 to 1998 also suggested the possible route of transmission related to this H3N2 virus.Conclusion The influenza pandemic occurred in Zhejiang province in 1998 was possibly caused by the importation of a newly identified H3N2 influenza variant via Hong Kong and New York in late 1997.

Molecular epidemiology of Norovirus in outbreaks of gastroenteritis in Zhejiang from 2006 to 2007 / 中华流行病学杂志

Objecfive To study the molecular epidemioiogical characteristics of Norovirus gastroenteritis outbreaks in Zhejiang.Methods During January 2006 and December 2007.fecal specimens of patients collected from outbreaks of acute viml gastroenteritis were tcsted for Norovirus.Epidemiological data were also collected.Noroviruses were detected by a reverse transcription polymerase chain reaction(RT-PeR)and Real.time RT-PCR.Some positive samples were randomly selected and Rrr-PCR products were sequenced.Comparing to the nucleotide sequences of norovirus genotype Ⅰ,Ⅱ reference strains from GenBank,sequence analysis was undertaken based on partial sequence of RNA dependent RNA polymerase(RdRp)and capsid protein(VPI)gene.Results 5 Outbreaks of viral gastroenteritis caused bv Norovirus were reported.A total of 63 stools were obtained from cases with acute gastroenteritis.Noroviruses alone were detected in 45 cases and the illness appeared in autumn.Phylogenetic analysis revealed that Norovirus belonged to G Ⅱ/G Ⅱ 4 type.The strains isolated from Zhejiang were almost identical on G Ⅱ/4 variants that causing epidemics in Beijing and in the Netherlands with the homology of 99.7%and 98.5%-99.O%respectively.Phylogenetic analysis revealed that the isolates were located at the same branch as the norovirus G Ⅱ/4 variants found in Beijing and Netherlands.Conclusion Norovirus iS a major cause of outbreaks of viral gastroenterifis in Zhejiang province.GenogroupⅡ/4 variants viruses were the prevalent strains.

Comparative analysis of measles genome between vaccine strain and wild-type strain in Zhejiang province of China / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the distinction between wild-type strain MVi/Zhejiang, CHN/7.05/4 and vaccine strain Shanghai-191 at genome level.</p><p><b>METHODS</b>After sequencing of measles wild-stain MVi/Zhejiang. CHN/7.05/4, the distinction between the wild-type strain and the vaccine strain was analysed by MEGA 3.1 software at genome level, and the antigen variation was studied by means of combining the epidemiological data.</p><p><b>RESULTS</b>There were 822 nucleotide differences (5.17%) and 161 amino acid differences between these two strains, including three glycosylation sites variation found. Meanwhile, the antigen ratio between wild-type strain and vaccine strain was found to be 5.66.</p><p><b>CONCLUSION</b>There should be certain differences between the contemporary wild-type strain MVi/Zhejiang, CHN/7.05/4 and vaccine strain Shanghai-191 at genome level, and the protective effects of measles vaccine should be studied further.</p>

Molecular characteristics and its evolution of the complete genome of avian influenza H5N1 virus isolated in Zhejiang province from 2002 to 2006 / 中华流行病学杂志

Objective To analyze the molecular characteristics and evolution reassortment of the complete genome of avian influenza H5N1 virus isolated in Zhejiang province in recent years. Methods Complete genomes of avian influenza H5N1 viruses isolated in Zhejiang province from 2002 to 2006 were sequenced. Molecular and evolution reassortment characterization of these virus strains were analyzed by Mega 3.0 bioinformatics software. Results Through study on the HA genes from all these strains,our data revealed that there were multiple basic amino acids at the cleavage site, which was typical for HPAIV.Compared with Gs/Guangdong/1/96,all these strains had a 20 amino acid deletion in the stalk of the NA, except for Dk/Zhejiang/2/02 and Ck/Zhejiang/8/03. Results from phylogenetic analysis showed that from2002 to 2003 the H5N1 viruses belonged to the genotype of B,W,X,Y,Z, and other genotypes were prevailed in corresponding year. However, different gene fragments of several strains belonged to different genotypes. Conclusion Recombinant might be widespread among the poultry in Zhejiang province. The genetic genes of viruses isolated after 2005, the Ck/Zhejiang/24/05 and Zhejiang/16/06 strains were almost all originated from the FJ-like genotype stably.

Study on the genetic characteristics of the avian influenza virus strain A/Zhejiang/16/2006 / 中华流行病学杂志

Objective To study the genetic characteristics of avian influenza virus strain A/Zhejiang/16/2006 which was isolated from the case first reported in Zhejiang province.Methods Complete genome of A/Zhejiang/16/2006 including eight segments were sequenced and compared on the genetic homogeneity with sequences of the similar strains provided through domestic and overseas sources.Results There were 11 amino acids showing differences on HA between A/Zhejiang/16/2006 and the H5N1 isolates of neighboring countries,but these differences had not affected the stability of glycosylation sites.In the NA region,20 amino acids located in the 49th to 68th position were found absent in the isolates obtained after 1997.Eight segments of H5N1 isolates,circulating in the mainland of China in the recent years,formed a separate branch compared to the strains in neighboring countries and there was also obviously different from the strains isolated in Hong Kong and Guangzhou in 1996 and 1997.However,several Chinese strains were close to the Hong Kong strains isolated in 1997 but diffferent from the current strains in the phylogenetic tree.Conclusion The influenza virus strain A/Zhejiang/16/2006 formed a separate branch with the strains isolated in the mainland of China in the past years but it presented an obvious difference with the isolates from the neighboring countries.

Genetic analysis on HA1 and NA regions of influenza virus subtype A3 isolates of Zhejiang province during 1998-2005 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the relationship between influenza epidemic and genetic characteristic on HA and NA regions of influenza virus subtype A3 isolates of Zhejiang province in the recent years.</p><p><b>METHODS</b>RNA of 25 influenza virus subtype A3 isolates, circulated in Zhejiang province during 1998 to 2005, was extracted. HA1 and NA regions were amplified and sequenced. All the sequence data were analyzed using BioEdit.</p><p><b>RESULTS</b>HA1 and NA regions of all the isolates belonged to 987nt and 1362nt, encoding protein of 329 and 454 amino acids respectively. Isolates shared amino acid homology of 90.9%-99.3% and 95.2%-99.5% on HA1 and NA regions, while divergence on HA1 was greater than that on NA region. During a period of 8 years, 30 amino acids on HA1 region were substituted and 14 of which refer to 4 antigenic determinant sites. Meanwhile,21 amino acids on NA region were substituted and 5 of which referred to 3 antigenic determinant sites. Significant divergences, both in HA1 and NA, were observed among isolates in 1998 and 2002, showing that they belonged to absolutely different branches. Additionally, influenza virus subtype A3 isolates identified in recent years, with 11 N-linked glyeosylation sites in HA1 region, had 5 sites more than early A/Aichi/2/68 strain. Since 1998,3 sites had been inserted in epidemic strains, indicating the accelerated trend of glyeosylation sites were increasing.</p><p><b>CONCLUSION</b>There is a correlation between antigenic drift of influenza virus subtype A3 and the two epidemics in Zhejiang province in 1998 and 2002.</p>

Study on the neutralization capacity of different types of human measles virus vaccine and the epidemic strains / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the neutralization capacities of different types of human serum to measles virus epidemic strains and vaccine strain.</p><p><b>METHODS</b>Neutralization antibody (NT) to Shanghai 191 and measles virus isolates in 2005 were tested using acute and convalescent serum samples from diagnosed measles patients, children serum samples collected before and after vaccination and serum samples of migrant residents, from 3 different regions. Additionally, animal immune serum referring to vaccine strain and 3 epidemic strains were prepared and used to undergo crossing neutralization test with corresponding strains mentioned-above. Antigenic ratios were calculated.</p><p><b>RESULTS</b>GMT value of NT of after-immune serum to vaccine strains was 50.82,1.86 times higher than that to MVi/ZJ/05/7 (GMT was 27.35), whereas GMT value of convalescent serum to MVi/ZJ/05/7 (GMT was 386.95) was obviously higher than that to vaccine strain (GMT was 1:151.83),and GMT value of migrant residents' serum in 3 regions to MVi/ZJ/05/7 were 2.22-4.17 times lower than that to vaccine strain. Meanwhile,the antigenic ratios between MVi/ZJ/ 99/1, MVi/ZJ/04/1, MVi/ZJ/05/7 and vaccine strain were found to be 4.28,5.24 and 5.66 respectively. Additionally,low NT titers to vaccine strain were found in patients' acute sera and GMT value was over 1:4.</p><p><b>CONCLUSION</b>There were obvious differences on neutralization antibody of different types of serum to measles vaccine strain and epidemic strains which indicating the antigenic diversity of epidemic strains had influenced the protective effectiveness of vaccine antibody to epidemic strains. It was of significance to carry on research projects on the antigenic diversity and effectiveness of measles vaccine.</p>

Study on the differences on HA1 regions between epidemic strains and vaccine strains of influenza virus subtype A3 from 1988 to 2005 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the differences between epidemic strains of influenza virus subtype A3 circulated in China and Occident in past 18 years, in genetic level, and vaccine strains recommended by WHO in corresponding time.</p><p><b>METHODS</b>Amino acid sequences of HA1 regions of the epidemic strains, which circulated in China and Occident from 1988 to 2005, and the vaccine strains of influenza virus subtype A3 were compared by BioEdit and analyzed on the differences of HA1 and it's antigen determinants</p><p><b>RESULTS</b>Differences between epidemic strains and vaccine strains recommended in corresponding year, both in HA1 and it' s antigen determinant regions, were obviously greater than that between epidemic strains and vaccine strains recommended in next round (P< 0.01). However, differences between epidemic strains in Occident and vaccine strains recommended in corresponding year were slightly greater than that between epidemic strains and vaccine strains recommended in next round and it was not marked (P >0.05). In addition, differences between epidemic strains and vaccine strains which being used for several years, whether in China or in Occident, constantly increased accompanying the used time prolonged.</p><p><b>CONCLUSION</b>There was an obvious lag between vaccine strains recommended by WHO, analyzed in genetic level, and epidemic strains of influenza virus subtype A3 circulated in China.</p>