狂犬病病毒的流行及防治

由于狂犬病病毒在犬类中传播迅速,危害性大,因此,随着城市、农村养犬数的增加,狂犬病疫情形势也越来越严峻。狂犬病症在感染初期是很难察觉到的,即使传统的把脉方式和现代先进的医疗检测仪也束手无策。据研究记载,狂犬病一旦发作,死亡率达百分之百,世人闻之,无不惊叹万分,更令人人惧怕这种病症会传染到自己。

狂犬病流行现状及防治措施

狂犬病是由狂犬病病毒引起的一种温血动物的中枢神经系统发生严重病变的急性、接触性、高致死性人畜共患传染病,是危害人及家畜的主要传染病之一,发病者几乎100%死亡。由于狂犬病病毒在犬类中传播迅速,

Cloning the Structure Genes and Expression the N Gene of Porcine Epidemic Diarrhea Virus DX

The structure genes spike(S) ,nucleocapsid(N) ,membrane(M) ,small membrane(sM) of a porcine epidemic diarrhea virus(PEDV) strain DX isolated in Gansu province,North-west of China,were cloned,sequenced and compared with published sequences of PEDV strains. The nucleotide sequences encoding the entire S,sM,M and N genes open reading frame(ORF) of DX were 4 152,231,681 and 1 326 bases long respectively. There were transcription regulatory sequences(TRSs) upstream of the initiator ATG of the S,N and M genes. The amino acids sequences of S,M and N contained 30,3 and 7 potential asparagine(N) -linked glycosylation sites. Homologous analysis and phylogenetic trees showed that DX had the closest relationship with strains LJB/06,JS-2004-2Z and CH/HLJH/06 that were also isolated from China and indicated the prevalence of some PEDV isolates in China were widespread since the JS-2004-2Z strain originated from the south of the China,and LJB/06 and CH/HLJH/06 were isolated from northeast China. The N gene was cloned using two primers which contained Nco I and BamH I restriction enzyme sites and subcloned into expression vector pET30a. The recombinant plasmid was then transformed into E.coli Rossta. SDS-PAGE showed there was a protein of about 55kDa as expected and Western blot indicated the N protein had biological activity.

Research on Propagation Characteristics of DifferentIsolates of Porcine Circovirus Type 2 in vivo

[Objective]The aim of this study is to explore the dynamic changes of Porcine circovirus type 2 (PCV2) and the propagation differences between different PCV2 strains.[Method]A rapid, sensitive and SYBR Green I-based real-time quantitative PCR assay was developed to detect PCV2 in mice. The Balb/c mice were inoculated with 200 μL of 1×10^6 TCID 50 /mL different strains of PCV2;the serum and tissues of mice were collected at different time. SYBR Green I fluorescent quantitative PCR was used to determine the viral titer in the serum and tissues of mice.[Result]The results indicated that the SYBR Green I PCR could speci fically detect PCV2 with high specificity. All strains were detected in the serum 14 d after infection, and 2007HA strain had the highest level of 1.21×10^8 copies/mL. The titers of all strains decreased 21 d after infection and then increased 28 d after infection. In addition, 2010NJ strain had the highest titer in serum 28 d after infection. The two PCV2b isolates, 2010NJ and 2009ZJ, had the highest titer in lungs and spleens. [Conclusion]All results showed that different PCV2 isolates have different proliferation ef ficiencies in Balb/c mice, even if they belong to the same subtype. In addition, the proliferation rate of 2009ZJ in visceral organs was significantly higher than that in serum. However, this phenomenon is not obvious for other strains. These results laid a foundation for the analysis of proliferation characteristics and pathogenicity of different PCV2 strains in vivo.

Construction of a chimeric hepatitis C virus replicon based on a strain isolated from a chronic hepatitis C patient

Subgenomic replicons of hepatitis C virus （HCV） have been widely used for studying HCV replication.Here,we report a new subgenomic replicon based on a strain isolated from a chronically infected patient.The coding sequence of HCV was recovered from a Chinese chronic hepatitis C patient displaying high serum HCV copy numbers.A consensus sequence designated as CCH strain was constructed based on the sequences of five clones and this was classified by sequence alignment as belonging to genotype 2a.The subgenomic replicon of CCH was replication-deficient in cell culture,due to dysfunctions in NS3 and NS5B.Various JFH1/CCH chimeric replicons were constructed,and specific mutations were introduced.The introduction of mutations could partially restore the replication of chimeric replicons.A replication-competent chimeric construct was finally obtained by the introduction of NS3 from JFH1 into the backbone of the CCH strain.

Pathogenicity of an FAdV-4 isolate to chickens and its genomic analysis

Fowl adenovirus serotype 4(FAdV-4)strain SD1511 was isolated from chickens with severe inclusion body hepatitis and hydropericardium syndrome in Shandong Province,China.The isolate was cultured in primary chicken embryo kidney cells.A study of pathogenicity indicated that SD1511 readily infected 7–35-d-old chickens by intramuscular injection and intranasal and oral routes,causing 50%–100%mortality.The 35-d-old chickens suffered more severe infection than 7-and 21-d-old chickens with mortality highest in the intramuscular injection group.The serum from surviving chickens showed potent viral neutralizing capability.The complete genome of SD1511 was sequenced and analyzed.The strain was found to belong to the FAdV-4 cluster with more than 99%identity with the virulent FAdV-4 strains isolated in China in recent years except for some distinct variations,including deletions of open reading frame 27(ORF27),ORF48,and part of ORF19.Our findings suggest that SD1511 might be used as a prototype strain for the study of pathogenesis and vaccine development.