Expression and characterization of albumin fusion protein canine IFNγ-CSA in baculovirus-insect cell expression system.

In this study, canine IFNγ was fused by a flexible linker with canine serum albumin to construct the fusion protein IFNγ-CSA for the purpose to design a long-acting canine IFNγ. The fusion protein was successfully expressed in baculovirus-infected Sf9 insect cells and was purified by salting-out and ion exchange chromatography. The IFNγ-CSA fusion possessed potent anti-viral assay against vesicular stomatitis virus in cultured cells. IFNγ-CSA was also stable at 37 °C up to 72 h compared with 8 h for IFNγ alone. In vivo pharmacokinetics demonstrated a significantly longer half-life for IFNγ-CSA (15.42 h) than for canine reIFNγ (1.51 h) in KM mice. These results indicate that IFNγ-CSA expression in the baculovirus system was successful and provide a promising long-acting cytokine for veterinary clinical applications.

First complete genome sequence of parainfluenza virus 5 isolated from lesser panda.

Parainfluenza virus 5 (PIV5) is widespread in mammals and humans. Up to now, there is little information about PIV5 infection in lesser pandas. In this study, a PIV5 variant (named ZJQ-221) was isolated from a lesser panda with respiratory disease in Guangzhou zoo in Guangdong province, southern China. The full-length genome of ZJQ-221 was found to be 15,246 nucleotides and consisted of seven non-overlapping genes encoding eight proteins (i.e., NP, V, P, M, F, SH, HN and L). Sequence alignment and genetic analysis revealed that ZJQ-221 shared a close relationship with a PIV5 strain of canine-origin (1168-1) from South Korea. The findings of this study confirm the presence of PIV5 in lesser panda and indicate this mammal as a possible natural reservoir. Furthermore they highlight the urgent need to strengthen viral surveillance and control of PIV5 in zoo animals.

Albumin fusion improves the pharmacokinetics and in vivo antitumor efficacy of canine interferon gamma.

Interferon (IFN)-γ plays an important role in antiviral, anti-proliferative, immunomodulatory and pro-inflammatory activities. However, the short therapeutic half-life of IFN-γ lessens its efficacy. Albumin fusion strategy is one of the most effective ways to improve the pharmacokinetic properties of cytokines. In this study, N- and C-terminal canine albumin fusions with canine IFN-γ were expressed in the baculovirus expression system. The fusion proteins stimulated Stat1 phosphorylation at levels similar to that of the recombinant IFN. The antiviral, anti-proliferative and promote apoptosis activity of CSA-IFN-γ was lower than IFN-γ-CSA and both were less than that of recombinant IFN-γ. In vivo pharmacokinetics demonstrated a significantly longer half-life for CSA-IFN-γ (21.73 h) than for IFN-γ-CSA (6.51 h) and canine reIFN-γ (2.22 h) in Wistar rats. CSA-IFN-γ was also more effective than IFN-γ-CSA and canine reIFN-γ at inhibiting growth of canine renal malignant histiocytosis in nude mice. Our results indicated that a canine serum albumin fusion at the N-terminus of IFN-γ prolongs its half-life and improves its in vivo antitumor activity.

Outbreak and genotyping of canine distemper virus in captive Siberian tigers and red pandas.

In this study, four canine distemper virus (CDV) strains were isolated from captive Siberian tigers (Panthera tigris altaica) and red pandas (Ailurus fulgens) during two separate CDV outbreaks in a zoo in Guangdong province, China. Sequence alignment and phylogenetic analyses based on the full-length hemagglutinin (H) and fusion (F) genes showed that they were closely identical to genotype Asia-1. Prior to confirmation of CDV in Siberian tigers, to control spread of the disease, a live attenuated combination CDV vaccine was used among almost all carnivore animals except for red pandas in which another recombinant combination CDV vaccine was used. However, about two months later, CDV re-emerged and caused the death among red pandas. Based on the vaccination records, the live combination vaccine could be considered an ideal weapon against CDV in zoo carnivore animals. Although the recombinant combination CDV vaccine was safe for red pandas, its protection effectiveness remains to be further investigated. Moreover, according to the outbreak interval time and sequence characterization, we suspected that stray cats circulating in the zoo were the intermediate host, which contributed to CDV spread from stray dogs to zoo animals. This study revealed the importance of vaccination and biosecurity for zoo animals.