Enhancing half-life and cytotoxicity of porcine respiratory and reproductive syndrome virus soluble receptors by taming their Fc domains.

Porcine reproductive and respiratory syndrome virus (PRRSV) is an important pathogen. Although tremendous effort has been made for the vaccine development, only modified live vaccines are widely used with arguably limited efficacy. Our previous study showed that the Fc-fused first four Ig-like domains of Sn (Sn4D-Fc) and the SRCR domains 5-9 of CD163 (SRCR59-Fc) can act as PRRSV soluble receptors (VSRs). In this study, we improved the VSR-based anti-PRRSV strategy by taming their Fc domains. Sequence alignment showed that the CH3 domain of pig IgG1 contained five putative amino acids involved in the interaction with the neonatal Fc receptor (FcRn). The M455L/N461S variant of SRCR59-Fc/Sn4D-Fc was created for the higher affinity of FcRn binding. Both rBac-SRCR59-lsFc/Sn4D-lsFc and rBac-SRCR59-Fc/Sn4D-Fc expressing the mutated or wild-type VSRs were generated for conceptual validation. Both immunofluorescence and Western blotting analysis showed that the two rBac vectors could express the encoded VSRs in cells with similar expression levels and anti-PRRSV effects. In the rBac-injected mice, the expression of SRCR59-lsFc/Sn4D-lsFc was significantly prolonged than that of SRCR59-Fc/Sn4D-Fc. Both plasma stability and serum half-life of the purified SRCR59-lsFc/Sn4D-lsFc were significantly improved than that of SRCR59-Fc/Sn4D-Fc. SRCR59-lsFc/Sn4D-lsFc-treated peripheral blood mononuclear cells showed significantly stronger cytotoxicity on PRRSV-infected primary alveolar macrophages than SRCR59-Fc/Sn4D-Fc-treated cells. For the first time, we demonstrated that both half-life and effector function of pig IgG Fc-fused proteins could be significantly improved by taming their CH3 domains. The rBac-SRCR59-lsFc/Sn4D-lsFc could be further developed as a novel anti-PRRSV reagent.

Gene Cloning, Tissue Expression Profiles and Antiviral Activities of Interferon-ß from Two Chinese Miniature Pig Breeds.

The porcine interferon (PoIFN) complex represents an ideal model for studying IFN evolution which has resulted from viral pressure during domestication. Bama and Banna miniature pigs are the two Chinese miniature pig breeds that have been developed as laboratory animal models for studying virus infection, pathogenesis, and vaccine evaluation. However, the PoIFN complex of such miniature pig breeds remains to be studied. In the present study, we cloned PoIFN-ß genes from Bama and Banna miniature pigs, detected their PoIFN-ß tissue expression profiles, prepared recombinant PoIFN-ß (rPoIFN-ß) using the E. coli expression system, and measured their antiviral activities against three different pig viruses. At the amino acid sequence level, PoIFN-ßs of the two miniature pig breeds were identical, which shared 100% identity with that of Congjiang Xiang pigs, 99.4-100% identity with that of domestic pigs, and 99.5% identity with that of three species of African wild boars. The tissue expression profiles of PoIFN-ß mRNA differed not only between the two miniature pig breeds but between miniature pigs and domestic pigs as well. The four promoter domains of PoIFN-ß of the two miniature pig breeds were identical with that of humans, domestic pigs, and three species of African wild boars. The recombinant PoIFN-ß prepared from the two miniature pig breeds showed dose-dependent pre-infection and post-infection antiviral activities against vesicular stomatitis virus, porcine respiratory and reproductive syndrome virus, and pig pseudorabies virus. This study provided evidence for the high sequence conservation of PoIFN-ß genes within the Suidae family with different tissue expression profiles and antiviral activities.

Gene cloning, prokaryotic expression and antiviral activities of interferon-αω from Chinese Bama miniature pigs.

Porcine interferon (PoIFN) complex represents an ideal model for studying IFN evolution that resulted from viral pressure during domestication. IFN-αω is an emergent subtype of type I IFNs which has been primarily characterized in domestic pigs. In this study, the PoIFN-αω cDNA was cloned from Chinese Bama miniature pigs by RT-PCR, and its tissue expression profile was analyzed by real-time RT-PCR. The cDNA was expressed in Escherichia coli as a His-tagged protein and purified by nickel affinity chromatography. The antiviral activities of recombinant PoIFN-αω (rPoIFN-αω) against four different pig viruses were measured using cytopathic effect (CPE) inhibition assay. Although the PoIFN-αω sequence of Bama miniature pigs was identical to that of domestic pigs, the tissue expression profiles differed significantly between the two pig species. The rPoIFN-αω showed dose-dependent pre-infection antiviral activities against porcine pseudorabies virus, vesicular stomatitis virus and porcine reproductive and respiratory syndrome virus, but not against porcine circovirus type 2. When used as treatment post infection with the three viruses, rPoIFN-αω showed the efficacy in decreasing CPE in the infected cells in a time-dependent manner. Therefore, the expressed rPoIFN-αω could be used as an antiviral agent against pig virus infections.

Epidemiology of CoViD-19 Pandemic: Recovery and mortality ratio around the globe.

Coronavirus Disease 2019 (CoViD-19) is the third type of coronavirus disease after severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) that appears in human population from the past two decades. It is highly contagious and rapidly spread in the human population and compelled global public health institutions on high alert. Due to genetic similarity of this novel coronavirus 2019 with bat virus its emergence from bat to humans is possible. The virus survive in the droplets of coughing and sneezing and spread around the large areas through infected person resulting in its rapid spread among people. Clinical symptoms of CoViD-19 include fever, dry cough, dyspnea, loose stool, nausea and vomiting. The present review discuss the origin of CoViD-19, its rapid spread, mortality rate and recoveries ratio around the world. Since its origin from Wuhan, the CoViD-19 spread very rapidly all across the countries, on April 17, 2020 this disease has affected 210 countries of the globe. The data obtained showed over 2.4 million confirmed cases of CoViD-19. Higher mortality rate was found in Algeria and Belgium as 15% and 13.95%, respectively. Lower mortality rate was found in Qatar 0.17% and Singapore 0.2%. Recovery versus deceased ratio showed that recovery was 68, 59 and 35 times higher than the death in Singapore, Qatar and Thailand respectively. It is concluded that 2019-novel corona virus is a zoonotic pathogen similar to MERS and SARS. Therefore, a barrier should be maintained between and across the human, household and wild animals to avoid such pandemics.