No abstract

In order to effectively identify the vaccine and field strains of Canine distemper virus (CDV), a new differential diagnostic test has been developed based on reverse transcription-polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP). We selected an 829 bp fragment of the nucleoprotein (N) gene of CDV. By RFLP analysis using BamHI, field isolates were distinguishable from the vaccine strains. Two fragments were obtained from the vaccine strains by RT-PCR-RFLP analysis while three were observed in the field strains. An 829 nucleotide region of the CDV N gene was analyzed in 19 CDV field strains isolated from minks, raccoon dogs and foxes in China between 2005 and 2007. The results suggest this method is precise, accurate and efficient. It was also determined that three different genotypes exist in CDV field strains in fur animal herds of the north of China, most of which belong to Asian type. Mutated field strains, JSY06-R1, JSY06-R2 and JDH07-F1 also exist in Northern China, but are most closely related to the standard virulent strain A75/17, designated in Arctic and America-2 genetype in the present study, respectively.

BackgroundAs a key link between innate and adaptive immune responses, the interferon (IFN) system is the first line of defense against viral infection. IFN, and in particular, IFN-α, has been used clinically as an effective therapeutic agent for viral infections. However, different subtypes of IFN-α demonstrate distinct antiviral activity. Therefore, it is important to identify IFN-α subtypes with high antiviral activity for the development of genetically engineered antiviral drugs.ResultsIn this study, we cloned the genes for 13 IFN-α subtypes from peripheral blood lymphocytes of the mink. The homologies of the 13 mink IFN-α genes were 93.6–99.3% and 88.8–98.4% at the nucleotide and amino acid sequence levels, respectively. In contrast to human and canine IFN-α subtypes, most mink IFN-α subtypes contained two N-glycosylation sites. We expressed and purified 13 mink IFN-α subtypes in Escherichia coli. The cytopathic effect inhibition assay showed that all the 13 recombinant mink IFN-α subtypes inhibited the propagation of vesicular stomatitis virus in WISH cells, with IFN-α2 and IFN-α12 demonstrating the highest activities. Furthermore, recombinant mink IFN-α2 and IFN-α12 significantly suppressed the propagation of canine distemper virus in Vero cells, with IFN-α2 demonstrating the highest activity.ConclusionsWe identified the mink IFN-α2 subtype as a promising candidate for the development of effective antiviral drugs.