Frequent Import and Multiple Sources of Dengue Fever have Changed the Epidemic Situation of the Disease in Fujian Province, China / 生物医学与环境科学（英文）

Objective@#The aim of this study was to update the epidemic situation of dengue fever (DF) and provide new insights for the consideration of disease control in Fujian province, China.@*Methods@#Details about DF cases in Fujian reported during 2004-2017 were collected and analyzed. The envelope (E) genes of isolates of dengue virus (DENV) were sequenced for phylogenetic analysis.@*Results@#The number of imported DF cases had increased dramatically since 2013, and the source regions expanded from Southeast Asia to South Asia, America, Oceania, and Africa, as well as the surrounding provinces. This resulted in local outbreaks and indigenous cases of DF that occurred more frequently, with 10 of 13 local outbreaks and 85.9% (1,252/1,458) of indigenous cases reported in 2013-2017. Compared with only two coastal cities before 2013, four coastal and one inland city in 2013-2017 experienced the local DF outbreaks. The phylogenetic analysis of E genes confirmed that the import of DENV, not only from abroad but also from the surrounding provinces, played an important role in dissemination and local outbreaks of DF in Fujian.@*Conclusions@#The frequent import of DF cases from not only abroad but also the surrounding provinces resulted in increased incidence, frequent local outbreaks, and expansion of distribution in Fujian in recent years. There is a need for urgent measures to improve disease control in this province.

RT-nPCR Assays for Amplification and Sequencing of VP1 Genes in Human Enterovirus A-D from Clinical Specimens / 生物医学与环境科学（英文）

Objective@#To develop RT-nPCR assays for amplifying partial and complete VP1 genes of human enteroviruses (HEVs) from clinical samples and to contribute to etiological surveillance of HEV-related diseases.@*Methods@#A panel of RT-nPCR assays, consisting of published combined primer pairs for VP1 genes of HEV A-C and in-house designed primers for HEV-D, was established in this study. The sensitivity of each RT-nPCR assay was evaluated with serially diluted virus stocks of five serotypes expressed as CCID @*Results@#The sensitivity of RT-nPCR assays for amplifying partial VP1 gene of HEVs was 0.1 CCID @*Conclusion@#This RT-nPCR system is capable of amplifying the partial and complete VP1 gene of HEV A-D, providing rapid, sensitive, and reliable options for molecular typing and molecular epidemiology of HEVs in clinical specimens.

Laboratory investigation of a clustered respiratory tract infection with human adenovirus / 中国人兽共患病学报

In order to investigate the pathogens associated with a clustered event of fever occurred in a kindergarten in Fuzhou,Fujian Province,samples were collected from pediatric cases in the kindergarten and screened for various possible viral agents by real-time PCR.Of 10 respiratory specimens,7 were positive of human adenovirus (HAdV).The positive samples were inoculated into HEp-2 cell-lines for viral isolation.The PCR products of the hypervariable regions of Hexon gene were sequenced,followed by BLAST searches for viral type identification.In comparison with the strains prevalent in domestic or abroad in recent years,the deduced amino acid sequences showed no amino acid mutation in the hypervariable regions of Hexon.Combined with clinical manifestation and field epidemiological data,human adenovirus type 7 could be confirmed as the pathogen linked to the clustered event.

Molecular epidemiology of HFMD-associated pathogen coxsackievirus A6 in Fujian Province, 2011-2013 / 病毒学报

In order to characterize the molecular epidemiology of HFMD-associated Coxsackievirus A6 (CVA6) in Fujian Province, a total of 1340 specimens from non-EV71 non-CVA16 HFMD patients were collected during 2011-2013. Isolated virus strains were identified and subtyped. Full-length coding regions for the VP1 gene of the predominant serotype CVA6 isolates were amplified and sequenced. Among the 375 non-EV71 non-CVA16 HFMD cases confirmed by virus isolation and molecular subtyping, 182 (48.5%) were found to be caused by CVA6, accounting for 7.9%, 16.2% and 39.6% HFMD-associated enteroviruses in FujianProvince during 2011, 2012, and 2013, respectively. Compared with general features observed in the HFMD epidemic, no difference in CVA6-specificity or severity rates was observed between geographical origins, gender, or age groups. Nucleotide sequence analyses of VP1 genes revealed high diversity levels of 16.2%-18.6% among CVA6 strains from Fujian Province, in contrast to the prototype CVA6 strain, and showed low levels of diversity in the amino acid sequences (4.3%-6.2%). Phylogenetic analysis also indicated that CVA6 isolates from Fujian Province were distinct from the prototype strain and other isolates from abroad; however, it was homologous to domestic strains, although the Fujian isolates clustered into multiple branches. These results suggested that significant changes in the pathogenic spectrum of HFMD in Fujian Province occurred during 2011-2013, as CVA6 was one of the predominant serotypes of HFMD. CVA6 isolates from Fujian Province were co-circulating and co-evolving with other domestic strains as multiple closely related CVA6 transmission chains were observed in Fujian Province overall and within each prefecture.

Characteristics of complete genome of pandemic A/H1N1/2009 influenza virus isolated in Fujian Province, China / 病毒学报

This study aims to investigate the characteristics of genomic variation of pandemic A/H1N1/2009 influenza virus isolated in Fujian Province, China. Complete genome sequence analysis was performed on 14 strains of pandemic A/H1N1/2009 influenza virus isolated from Fujian during 2009-2012. All virus strains were typical low-pathogenic influenza viruses, with resistance to amantadine and sensitivity to neuraminidase inhibitors. Eight genome fragments of all strains were closely related to those of A/California/07/2009 (H1N1) vaccine strain, with > or = 98.2% homology. Compared with the vaccine strain, the influenza strains from Fujian had relatively large variation, and variation was identified at 11 amino acid sites of the HA gene of A/Fujiangulou/SWL1155/2012 strain, including 4 sites (H138R, L161I, S185T, and S203T) involved inthree antigen determinants (Ca, Sa, and Sb). In conclusion, the influenza vaccine has a satisfactory protective effect on Fujian population, but the influenza strains from Fujian in 2012 has antigenic drift compared with the vaccine strain, more attention should therefore be paid to the surveillance of mutations of pandemic A/H1N1/2009 influenza virus.

Construction of sub-unit dengue vaccines and analysis of its immunogenicity / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To construct sub-unit vaccines of dengue virus type 1 to 4 and to analyze its immunogenicity.</p><p><b>METHODS</b>Envelope domain III s of dengue serotypes 1 and 2, as well as 3 and 4, were spliced by a linker (Gly-Gly-Ser-Gly-Ser)3 and cloned into vector pET-30a, then transformed into E. coli to express recombinant fusion proteins. The recombinant proteins were purified by high-performance liquid chromatography and mixed to immunize BALB/c mice. The neutralizing antibodies were tested by neutralizing assay, as well as in newborn mice challenged intracranially with dengue virus type 1 to 4.</p><p><b>RESULTS</b>Mice immunized with proteins could produce neutralizing antibodies, with titers of 1:34. 9, 1: 45.3, 1: 24.7 and 1:38.4 for DEN-1 to 4 respectively. 100% newborn mice challenged with DEN-1 or 2 in combination with sera from mice immunized with recombinant proteins were protected, whereas 83% protection was obtained when challenged with DEN-3 or 4.</p><p><b>CONCLUSION</b>The recombinant proteins possess excellent immunogenicity to induce neutralizing antibodies and would be valuable for development of a tetravalent sub-unit vaccine.</p>

Study on the epidemiology and etiologic agent of Dengue fever outbreaks in Fuzhou in 2004 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the epidemiology and etiologic characteristics of a Dengue fever outbreak in Fuzhou from the beginning of September to the end of October in 2004 in order to understand the source of infection.</p><p><b>METHODS</b>Data on descriptive epidemiology was collected to study the characteristics and related factors to the epidemic. Dengue virus was isolated through the use of C6/36 cell line while viral serotypes were identified by indirect immunofluorecent assay with type-specific monoclonal antibody. The sources of infection were traced by nucleotide sequencing.</p><p><b>RESULTS</b>During the epidemic, 93 cases occured consistently with the region entomoplily growth and decay. The viruses of 6 strains isolated from 10 patients' blood specimens were identified as dengue virus type 1. Phylogenetic evidence suggested that the viral isolate had high genetic relation with the isolates from Kampuchea (DENV-1/KHM/2001; GenBank Accession No. L0904278).</p><p><b>CONCLUSION</b>The epidemic was caused by introduction of patients migrating into Fuzhou.</p>

Expression of truncated 56 kDa antigen gene of Orientia tsutsugamushi in different vectors / 中华流行病学杂志

<p><b>OBJECTIVE</b>To construct recombinant plasmids containing the truncated gene of the major surface antigen sta56 of Orientia tsutsugamushi (Ot.) Karp strain for expression antigen in E. coli so as to compare the expression efficiency in different systems.</p><p><b>METHODS</b>From the recombinant plasmid TOPO-sta56 containing sta56 of Orientia tsutsugamushi Karp strain, several truncated genes of sta56 with different length were amplified and subcloned into the expression vectors pPROEX HTb and pET30a. These genes were expressed in E. coli DH5alpha and BL21(DE3) respectively when induced by IPTG. The expressed recombinant proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot.</p><p><b>RESULTS</b>Six recombinant plasmids containing truncated sta56 genes of different length were constructed as follow: pHTbOt957, pHTbOt498, pHTbOt342 and pETOt957, pETOt498, pETOt342. The recombinant sta56 proteins were highly expressed as 6 x His fusion proteins in E. coli DH5alpha and BL21(DE3) respectively. The fusion proteins showed as different bands of different molecular weight respectively when analyzed with SDS-PAGE. Western blot demonstrated that the recombinant proteins were recognized by the positive serum of Ot. patients.</p><p><b>CONCLUSION</b>The sta56 gene of Orientia tsutsugamushi Karp strain could be highly expressed in E. coli and its expression showed better efficiency in pET30a than in pPROEX HTb. The recombinant sta56 antigen with immunoreactivity could be used as diagnostic reagent for Ot. infection.</p>