Effect of Coxsackievirus A16 on primary gerbil muscle cells and its mechanism / 预防医学

Objective To explore the killing mechanism induced by Coxsackievirus A16 (CV-A16) in primary muscle cells of gerbils, and to lay the foundations for elucidation the pathogenesis of CV-A16 and the further application of gerbil model. Methods The primary muscle cell model was established by digestion of trypsase/collagenase double enzyme hydrolysis. Primary muscle cells were infected by different dose of CV-A16 and the cell viability was detected by CCK-8 assays. Chromatin condensation and break were measured by Hoechst 33258 staining. The early and last stage of apoptosis cells were measured by AnnexinV/PI double staining. Expression changes of Caspase-3, Caspase-8, JNK and NF-κB pathway proteins were detected by Western Blot. Results The cell viability were 88.95％ and 64.05％ at groups of different multiplicity of infection (MOI=0.50 and 1.00), which was significantly different from those of the negative control group. The cell viability and multiplicity of infection were negative correlation (rs=-0.857, P=0.014) . The apoptosis rates were 7.2％, 21.8％ and 50.7％ at MOI=0.01,0.10 and 1.00 groups, respectively. The apoptosis rate and MOI were positive correlation (rs=1.000, P<0.001) . When the primary cells were infected by CV-A16, cleavage of Caspase-3 and Caspase-8 were detected. Western Blot assays showed that the expression of NF-κB pathway proteins IκBα, p65 and p-p65 were reduced, which was different in enterovirus 71-infected cells. The JNK kinase was actived. Conclusion CV-A16 could induce apoptosis in primary muscle cells from gerbils.

Study on comprehensive monitoring of mouse and effect of hemorrhagic fever with renal syndrome vaccine in high prevalence areas of natural focus infectious disease of Zhejiang province in 1994--2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the comprehensive monitoring mechanism of mouse and the effect of hemorrhagic fever with renal syndrome (HFRS) vaccine in the high prevalence areas of natural focus infectious disease of Zhejiang province in 1994 - 2010.</p><p><b>METHODS</b>The night trapping method was used to monitor the population proportion, density and the rate of hantavirus (HV) carriers in mice in Xikou township Longyou county in August and September from 1994 to 2010. The healthy residents in Xikou township aged 16 to 60 years were recruited. The subjects were randomly selected as vaccination group and control group according to age, sex, occupational distribution (10 178 in intervention group and 16 159 in control group). Intervention group was given purified and inactivated vaccine from suckling mouse brain, while the control group received no intervention. The prevention effect was evaluated by protective rate of vaccine.</p><p><b>RESULTS</b>The mouse population was stable in the sixteen years and the apodemus agrarius was the main type (76.5% (564/737)). The average density of mouse was 4.73% (1170/24 727). The average rate of virus carrier of mouse was 3.87% (41/1033). In 1994 - 1995, the density of mouse was 22.82% (186/815) and the rate of virus carrier was 7.0% (10/143). In 2009 - 2010, the density of mouse decreased to 2.75% (119/4330) and the rate of virus carrier was 5.5% (13/237). The average antibody positive rate of mouse from 2005 to 2010 was 4.8% (35/728) and the rate was 4.4% (6/138), 0.0% (0/113), 11.8% (16/136), 1.0% (1/104), 3.7% (4/109) and 6.3% (8/128) in each year (P < 0.01). The protective rate of HFRS vaccine was 96.2% (1 case in intervention group and 41 cases in control group).</p><p><b>CONCLUSION</b>The density of mouse decreased significantly in Zhejiang province. The rate of virus carrier of mouse is stable. The vaccine is effective.</p>

Genotype of hantavirus in Zhejiang province / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To identify the genotype and clades of hantavirus (HV) in Zhejiang province.</p><p><b>METHODS</b>The partial S and M segment of the HV in Zhejiang province were amplified with RT-PCR using genotype-specific primers, and then were sequenced and compared with other known hantaviruses.</p><p><b>RESULTS</b>The genotype of 11 strains were HTNV and other 7 strains were SEOV by homology and phylogenesis analysis, yet the clade distribution was significantly different among foci of Zhejiang with 5 clades of HTNV and 3 clades of SEOV. There also existed special clade of HTNV named ZNB-1, ZNB-2, A3 and of SEOV named Gou3, ZJ5. The homology of M segments of ZNB-1 and ZNB-2 with other HTNV clades were 69.7%-74.0% except Nc167, A3 with other HTNV clades were 73.6%-76.3% except B78.</p><p><b>CONCLUSION</b>Zhejiang province is co-circulating with HTN and SEO. Say the least of the clades are 5 of HTNV and 3 of SEOV and there also existed special clade of HTNV and SEOV.</p>

A study of immunoassay by using quantum dots to detect Hantavirus infection / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To develop a new method to detect anti-Hantavirus IgG antibodies (HV IgG) based on quantum dots (QDs) and indirect immune technique.</p><p><b>METHODS</b>The carbodiimide crosslinking method was used to couple protein G and goat antihuman IgG on the surface of water-solubility QDs. The coverglass covered HV antigen was used as carrier, and QDs-PG-IgG conjugates was used as labeled second antibody to detect the HV-IgG in the serum samples. The detecting conditions were optimized.</p><p><b>RESULTS</b>The optimum reaction time, pH and goat antihuman IgG concentration for conjugating the QDs with goat antihuman IgG were 6.0, 2h, and 20 microg/ml, respectively. The optimum working dilution of QDs-PG-IgG conjugates was 1: 200. The detection limit of the serum samples was about 1: 1280 dilution.</p><p><b>CONCLUSION</b>The method established in this study has been demonstrated to be a specific, sensitive, rapid test for detecting HV antibodies, laying the foundation of single molecule detection. The anti-fluorescence quenching ability of this method was significant improved.</p>

The expression and bioactivity of S gene in Vero-E6 cells using baculovirus vector / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>The S gene of a Hanta Virus (HV) Z10 strain was cloned into a baculovirus shuttle bacmid pDual-CMV contained a CMV promoter to generated a recombinant baculovirus BAC-pDual-CMV-HVS, then the recombinant baculovirus was transfected into Vero-E6 cell. The cells with recombinant baculovirus were applied to the detection of HV antiserum.</p><p><b>METHODS</b>To generate the recombinant baculovirus BAC-pDual-CMV-HVS, the sequence of CMV promoter was obtained from the plasmid pEGFP-N1 by PCR, and subsequently cloned to the baculovirus shuttle bacmid pFastBacDUAL resulting the recombinant plasmid pDual-CMV. Then the sequence of HV-S gene was inserted to the plasmid pDual-CMV, to generate the plasmid pDual-CMV-HVS. Plasmid pDual-CMV-HVS was transformed into the DH10BAC competent cells to get the recombinant baculovirus BAC-pDual-CMV-HVS. The antigen substrate slides were made by transfecting the recombinant virus into Vero-E6 cells.</p><p><b>RESULTS</b>The plasmid pDual-CMV-HVS was verified by sequencing. The recombinant virus BAC-pDual-CMV-HVS was generated according to the protocol of the baculovirus and transfected into Vero-E6 cells. The expression of the HV-S gene was verified by positive HV antiserum.</p><p><b>CONCLUSION</b>[corrected] The recombinant virus were successfully generated and applied to prepare the antigen substrate slides. The antigen substrate slides was conveniently prepared without special equipments, and can be used to detect the antiserum of HV virus.</p>

Study on the transmission of Hantaan virus and Orientia tsutsugamushi by naturally dual infected Leptotrombidium scutellare through stinging / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate whether Leptotrombidium scutellare could be naturally infected by both Hantaan virus (HV) and Orientia tsutsugamushi (OT) and transmission status by stinging.</p><p><b>METHODS</b>3459 Leptotrombidium scutellares from mice bodies and 3265 which were free were collected in the epidemic area of hemorrhagic fever with renal syndrome (HFRS) and tsutsugamushi disease.15 days later, the suspensions of lung and spleen of mice with 6 in a group stung by 1, 5 or 10 infected mites were injected intra-cerebrally into other mice for the detection of HV and OT in the next 6 generations of the mice, with immunofluorescent antibody technique (IFAT) and Giemsa staining technique. The passages of Vero-E6 cells inoculated on the aseptic filtrations from different number of infected mites were used to detect HV and OT pathogens. HV-RNA and OT-DNA were detected by PCR.</p><p><b>RESULTS</b>After passage, HV positive mouse body mite group out of both 5 and 10 mites in the sixth generation, OT positive mouse body mite group out of the 10 mites in the sixth generation, both HV and OT positive mouse body mite group out of 1 mite in the fifth and sixth generation, both HV and OT positive mouse body mite group out of 5 and 10 mites in the sixth generation, and free mites group out of 1, 5 and 10 mites in the sixth generation, were found one mouse infected by both HV and OT, respectively. Out of the fourth generation of Vero-E6 cells, one sample was found both HV and OT positive out of 5 and 10 HV and OT mouse body mite group, respectively. In the sixth generation, both HV and OT positive cells were detected in one mouse mite group and the 1, 5, 10 free mite groups, respectively. HV-RNA and OT-DNA were all detected by PCR.</p><p><b>CONCLUSION</b>Both HV and OT could be coexisted in wild Leptotrombidium scutellare and transmitted by stinging.</p>

Molecular evolution analysis of hantaviruses in Zhejiang Province / 病毒学报

In order to analyze the molecular epidemiology of Hantavirus (HV) in Zhejiang Province, the complete M and S genome sequences of 12 HV strains from different hosts and locations in Zhejiang Province of China during the period of 1981-2007 were analyzed on genetic evolution by DNAstar and MEGA 4.0 software in this research. Phylogenetic analyses revealed that HTN and SEO strains were co-circulating in Zhejiang Province, and the difference in sequence similarity and the phylogeny was closely related to the isolated regions, but had no distinct relationship with the isolate year and the host, indicating a relationship between epidemiology of HFRS and the distribution region, especially in HTNV. The isolates in the same region could be assigned in same or near phylogenetic clade sharing high sequence similarity. Interestingly, the Gou3 strain and ZJ5 strain isolated from Jiande region in Zhejiang Province formed a distinct phylogenetic lineage in SEOV clade, and different from the other SEOV variants outside China. We believed that the special SEOV variants were distributed in Jiande region.

The distributions of mosquito vectors carrying Japanese encephalitis virus in Zhejiang province / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the natural infection and genotype of Japanese encephalitis virus in mosquitoes and swine in some areas of Zhejiang province.</p><p><b>METHODS</b>Samples of mosquitoes and sera of swine were collected in three counties (Xianju, Longquan and Cixi) of Zhejiang province from May to October in 2007. 10 662 mosquitoes were collected during 2007, of which, C.pipiens pallens and C.quinquefasciatus were the most dominant species and 204 pig serum samples were detected. Japanese encephalitis virus in mosquitoes were detected by virus isolation and real time RT-PCR. The antibody against Japanese encephalitis virus in swine was detected by ELISA. The isolated strain were identified by real time RT-PCR. The PrM gene of the isolated strain was amplified by RT-PCR. Three strains were typed by the gene of PrM.</p><p><b>RESULTS</b>Seven positive mosquitoe samples were identified by real time RT-PCR. Three strains were isolated and identified by real time RT-PCR. The PrM gene was cloned and sequenced. The phylogenetic analysis showed that three isolates belong to genotype I of Japanese encephalitis virus. Of 204 swine serum samples, 121 positive samples were identified positives. Above 50% sera samples from swine were positive in June.</p><p><b>CONCLUSION</b>The vector of Japanese encephalitis virus existed and carried the Japanese encephalitis virus in these areas of Zhejiang province. Three strains of Japanese encephalitis virus were isolated from mosquito pools collected in Zhejiang province. It should be the first isolation of genotype I Japanese encephalitis virus in Zhejiang province in recent years.</p>

Expression of partial S gene of Hantavirus Z10 in Pichia pastoris / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>The purpose of this study is to express partial S gene of Hantavirus Z10.</p><p><b>METHODS</b>The 300 bp S gene of Z10 strain was synthesized by using a successive PCR method for the optimal expression in Pichia pastoris and subcloned into pMD19-T. The SP300 gene was constructed into pPICZaA and sequenced. The recombinant pPICZaA-SP300 and pPICZaA-S300 was transformed into Pichia with LiCI.</p><p><b>RESULTS</b>The recombination Pichia were cultivate, and expressed the SP300 or S300 gene induced in Pichia by methanol.</p><p><b>CONCLUSION</b>The nucleocapsid secreted from the Pichia can be detected by ELISA and WesternBlot.</p>

Development and evaluation of TaqMan-based one-step reverse transcription-polymerase chain reaction assay for the detection of Japanese encephalitis virus / 中华流行病学杂志

Objective To establish a TaqMan based real-time reverse transeription-polymerase chain reaction (RT-PCR) assay for the detection of Japanese encephalitis virus. Methods The gene sequences of Japanese encephalitis virus downloaded from the GenBank was aligned, using the biologic software. Specific primers and probes were designed in the conserved region of the C gene for Japanese encephalitis virus. The real-time RT-PCR reactive condition was optimized and the sensitivity, specificity and the stability of the assay were evaluated. Mosquitoes collected from Zhejiang province were detected by this assay. Results Mg2+, primer and probe were optimized at 5 mmol/L, 0.2 μmol/L and 0.1 μmol/L respectively. The specificity of the assay was high and there were no cross reactions with dengue virus, rabies virus, seoul virus or hantan virus. The detection limits of the assay was 0.1 TCID50. Results from preliminary application showed that TaqMan RT-PCR for Japanese encephalitis virus was sensitive, easier and faster to perform the process of traditional virus isolation and identification. It took only three hours to extract viral RNA and perform the real-time RT-PCR. Conclusion This TaqMan-based one-step RT-PCR assay was a quick, sensitive and specific tool for molecular diagnosis of Japanese encephalitis virus.

Study on the difference of genes and the type identification of hantavirus from Lishui,Zhejiang province / 中华流行病学杂志

Objective To isolate hantavirus from Lishui county-one of the epidemic regions for hemorrhagic fever with renal syndrome(HFRS),in Zhejiang province,and to identify the serotype and molecular/biological characteristics of a new HTN subtype hantavirus(HV)strains,hopefully to provide evidence for HFRS prevention and therapy.Methods Data on the host animals was collected from Lishui,Zhejiang province in 2007.Direct immunofluorscece assay was adopted to determine HFRS antigens and the lung tissues from HV infeeted Vero-E6 cells for HV isolation,then total RNA was extracted from Hantavirus Lishui strains and amplified by RT-PCR M,S segments of strains genome were also clened and sequenced and compared with those of other strains of HV Results 2 strains virus(ZLS6-11 and ZLS-12)Were successfully isolated from 7 positive lung samples of mice and were identified as HTNV by anti-McAb and phylogenetic analysis.With sequence compation.We found that 2 strains with complete M and S segment had higher homology with HTN-type strains than with other types of HV,but 13.4%-20.7%and 10.3%-16.1%of the genes were found which were difierent from HTNV.The phylogenetic trees constructed by complete S and M segment showed that ZLS6-11 and ZLS-12 strains were located in HTNV group,and structured independent embranchment.Conclusion ZLS6-11 and ZLS-12 Strains were believed to belong to HTN-type and phylogenetically different from the HTNV.

Complete genome sequence analysis of Japanese encephalitis virus newly isolated in China / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To study the complete genome sequence of Japanese encephalitis virus (JEV) strain XJ69 isolated in ZheJiang province and explore its evolution.</p><p><b>METHODS</b>Overlapping primers were designed according to the full-length genomes from GenBank. RT-PCR was used to amplify the fragments and RT-PCR products were cloned T vector, sequenced and analyzed.</p><p><b>RESULTS</b>The genome of strain XJ69 and XJP613 were 10 964 nucleotides in length with a single open reading frame encoding 3432 amino acids. Comparison of the complete genome sequences of different JEV isolates showed XJ69 and XJP613 were 83.5%-99.2% and 83.4%-99.4% nucleotide sequence homology among them respectively, which resulted in 94.8%-99.7% amino acid sequence homology. Phylogenetic analysis through PrM/C,E and full-length genome showed that the XJ69 and XJP613 strain belonged to genotype I.</p><p><b>CONCLUSION</b>The nucleotitede sequence and deduced amino acid sequence of XJ69 and XJP613 strain were similar to that of those of genotype I of Japanese encephalitis virus. It belonged to genotype I and were close to the isolates SH17M-07.</p>

Molecular characterization of hantavirus Zhejiang isolate ZT10 strain from M. fartis / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To learn about the complete genomic sequence of the Seoul virus strain ZT10 isolated from M. fartis.</p><p><b>METHODS</b>The total RNA was extracted from the infected Vero E6 cells and amplified by RT-PCR. The purified PCR products were cloned into T-vector and sequenced.</p><p><b>RESULTS</b>The results demonstrated that the complete genome of ZT10 was comprised of L(6530), M(3651) and S(1753) segments which encoded 2151-1133 and 429 amino acids respectively.</p><p><b>CONCLUSION</b>Analysis of sequence revealed that the ZT10 belonged to Seoul virus. The nucleotide sequence identity of the M gene with Seoul virus was 84.0%-96.3%. The identity with Hantan vrisu (Prospect Hill virus, Tula virus) isolated from M. fartis was 57.5%-60.9%. The sequence identity of the S gene with Seoul virus was 87.9%-96.0% at nucleotide level and 96.9%-97.9% at amino acid level.</p>

Molecular characterization and sequence comparison of the M and S segments of Hantavirus ZJ5 strain / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>In order to understand the molecular characters of Hantavirus ZJ5 strain, its complete M and S genome were sequenced and compared with that of other hantavirus strains.</p><p><b>METHODS</b>We prepared the total RNA from ZJ5. Infected cells and the raw or purified RT-PCR product was cloned and sequenced.</p><p><b>RESULTS</b>With sequence compation, we found ZJ5 strain complete M and S segment had higher homology with SEO-type strains than other type of HV, but differential genes were 11.7%-19.2% and 6.7%-14.5% from SEOV. The phylogenetic trees constructed by complete M ind S segment showed that ZJ5 strain was located in SEOV group, and structured alone embranchment.</p><p><b>CONCLUSION</b>The ZJ5 strain was believed to belong to SEO-type virus,and suggest that ZJ5 strain is a new subtype S SEOV group,and structured alone embranchment.</p><p><b>CONCLUSION</b>The ZJ5 strain was believed to belong to SEO-type virus, and suggest that ZJ5 strain is a new subtype from other SEO viruses.</p>

Isolation and identification of Japanese encephalitis virus from mosquitoes in Zhejiang province / 中华流行病学杂志

Objective To study the situation of arboviruses carried by mosquitoes in Zhejiang province.Methods Mosquitoes were collected from Zhejiang province in 2007.Virus strains were isolated by the inoculation of homogenates of the mosquitoes onto BHK-21 cell line.The isolated strains were identified by serological(IFA)and molecular methods(RT-PCR).Results Two strains were isolated from mosquitoes causing cytopathogenic effect(CPE)in BHK-21 cells.Results from serological tests showed that both of the two strains were positive for the antibody to Japanese encephalitis virus(JEV).PrM and E gene were then cloned and sequenced.Results from the phylogenetic analysis showed that the isolates belonged to genotype Ⅰ JEV while through sequence analysis it showed that the homology of nucleotide sequences and amino acid sequences between the two strains were 99.0% and 98.8% respectively.Compared with the JEV vaccine strain SA14-14-2 and two strains,the homology of nucleotide sequences Was up to 87.7% and homology of amino acid sequences was up to 96.4%.When comparing with the vaccine strain SA14-14-2,there were 14 common amino acid variations in all the two strains.Conclusion Two strains of JEV were isolated from mosquitoes collected in Zhejiang province whiCh was the first isolation of genotype Ⅰ JEV in the province in recent years.

Study on the recombinant expression of Hantaan virus protein N and the establishment and application of rNP-IgM direct capture ELISA / 中华流行病学杂志

<p><b>OBJECTIVE</b>To clone the gene encoding nucleocapsid protein (NP) of hantavirus strain Z10 (HV-Z10), to construct its prokaryotic expression system as well as to establish a rNP-IgM direct capture ELISA based on HRP-labeled recombinant NP (rNP), in order to detect serum samples of patients suffering from hemorrhagic fever with renal syndrome (HFRS) and to evaluate the effects of detection.</p><p><b>METHODS</b>Gene encoding NP of strain HV-Z10 was amplified by PCR and then its prokaryotic expression system pET28a-Z10N-E. coli BL21DE3 was constructed, using routine genetic engineering method. SDS-PAGE was applied to measure the expression of rNP and ion-exchange plus Ni-NTA-affinity chromatography was performed to purify the recombinant product. Western blot assay was used to determine the specific immuno-reactivity of rNP while HRP-labeled rNP-IgM direct capture ELISA was established to detect the serum samples from 95 cases of confirmed HFRS patients. The detection effect was compared with that by routine HV-IgM indirect capture ELISA method.</p><p><b>RESULTS</b>pET28a-Z10N-E. coli BL21DE3 was able to express rNP with high efficiency. The purified rNP only showed a single protein fragment in the gel after SDS-PAGE. HV-IgG could efficiently recognize rNP and hybridize with the recombinant protein. 94.73% (90/95) of HFRS patients' serum samples were positively confirmed by rNP-IgM direct capture ELISA, while a positive rate of 92.63% (88/95) in the same samples was confirmed by HV-IgM indirect capture ELISA. The distributions of A450 values of the serum samples detected by the two IgM capture ELISAs as well as the changes of the A450 mean values from several serum samples with different dilutions were similar.</p><p><b>CONCLUSION</b>We successfully constructed a high efficient prokaryotic expression system of NP encoding gene of hantavirus strain HV-Z10. The rNP-IgM direct capture ELISA that established in this study could be used as a new serological test for HFRS diagnosis because of its simplicity, safety, with high sensitivity and specificity.</p>

Molecular analysis on the S gene of three Crimean-Congo hemorrhagic fever virus strains in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To compare the molecular characteristics of 3 Crimean-Congo hemorrhagic fever viruses(CCHFV) isolated in Xinjiang province.</p><p><b>METHODS</b>YL05035, YT05099 and LT05146 were isolated in 2005 from Hyalomma ticks and viral RNA was extracted from suckling mouse brains infected with these three strains respectively. The polymerase chain reaction(PCR) products of S segments from the 3 strains of CCHFV were directly sequenced.</p><p><b>RESULTS</b>The full-length'S RNA from the 3 strains of CCHFV all comprised 1673 nucleotides with ORF of them including 1449 nucleotides and encoding a protein which comprised 482 amino acids in a viral complementary sense. The sequences indicated that the three strains of CCHFV isolated from ticks in Xinjiang province were highly homologenic. Data from the phylogenetic analysis showed that the obtained sequences were identical. The homology between 3 strains of CCHFV was 99.5%. Their homologies compared with that of the other strains isolated from other region of Xinjiang were also high at nucleotide levels (92.7%-99.8%). The three strains which were clustered together with 7001 strain and 79121 strain (isolated from patient and rat in Xinjiang respectively) was only different by 2%-3%. The genetic difference from the prototype CCHFV Nigerian strain IBAR10200 was 13%. In comparison, the Nigerian CCHFV tick isolate was more divergent when compared with the reference China strains 66019 and with the three variants mentioned above.</p><p><b>CONCLUSION</b>The CCHFV isolated from China comprised a group of genetically high conserved strains.</p>

Molecular Cloning and Nucleotide Sequence Analysis of th e M Genome Segment of Hantavirus Z37, a Chinese HFRS Vaccine Strain / 中国病毒学

One of the strain of bivalent HFRS vaccine, Z37 strain was isolated from Rattus norvegicus and identified as SEO virus by serological test. The M segment cDNA of Hantavirus Z37 strain was obtained by reverse transcripti on and polymerase chain reaction, subsequently cloned into pGEM-T vector. The s equence of positive recombinants was determined by the method of dideoxy chain t ermination, which revealed that the M genomic segment is 3651 nucleotide in len gth with a predicated long open reading frame encoding a protein of 1133 amino acids. Comparison with HNT type (76-118, A9, HV-114 strains) indicated that th ere were 71.8%～72.1% homology at the nucleotide level, 76.2～76.7% homology at the amino acid level. Comparison with SEO type (R22,L99,80-39 strains) showed 95.3～96.1 homology at the nucleotide level, 95.3～99.2% homology at the amino acid level. The results of nucleotide and amino acid comparison indicated that Z 37 strain is SEO viruses in molecular level.