The evolution, complexity, and diversity of swine influenza viruses in China: A hidden public health threat.

Swine influenza viruses (SIVs), including H1N1, H1N2, and H3N2, have spread throughout the global pig population. Potential pandemics are a concern with the recent sporadic cross-species transmission of SIVs to humans. We collected 1421 samples from Guangdong, Fujian, Henan, Yunnan and Jiangxi provinces during 2017-2018 and isolated 29 viruses. These included 21H1N1, 5H1N2, and 3H3N2 strains. Genome analysis showed that the domestic epidemic genotypes of H1N1 were mainly G4 and G5 reassortant EA swine H1N1. These genotypes have a clear epidemic advantage. Two strains were Clade 6B.1 pdm/09H1N1, suggesting a possible pig-to-human transmission route. Notably, three new H1N2 genotypes were identified using the genomic backbones of G4 or G5 viruses for recombination. The identification of various subtypes and genotypes highlight the complexity and diversity of SIVs in China and need for continuous monitoring of SIV evolution to assess the risks and prepare for potential influenza pandemics.

Genome sequence of canine parvovirus strain SC02/2011, isolated from a puppy with severe diarrhea in south China.

A widespread hemorrhagic gastroenteritis in young dogs occurred in South China. A virulent field canine parvovirus (CPV) strain, SC02/2011, was isolated from a puppy showing enteric signs in Guangdong, China. The genome of CPV strain SC02/2011 was sequenced and analyzed, which will promote a better understanding of the molecular epidemiology and genetic diversity of CPV field isolates in South China.

Characterization of Canine Gingival-Derived Mesenchymal Stem Cells and Their Exosomes.

Mesenchymal stem cells (MSCs) can be isolated from numerous tissues and have the potential for self-renewal and multidirectional differentiation. Evidence is accumulating which suggests that MSCs are also present in the gingival tissue. This study aimed to evaluate the feasibility of collecting, purifying, and amplifying gingival-derived MSCs (GMSCs) from canine gingiva and to obtain GMSC-derived exosomes (GMSC-exo). GMSCs were isolated and cultured; furthermore, cellular immunofluorescence demonstrated that GMSCs possess characteristic MSC markers, and in vitro differentiation was induced, indicating that GMSCs can differentiate into multiple lineages. GMSC-exo was successfully extracted from GMSCs supernatant and found that they exhibit the typical characteristics of exosomes as analyzed by transmission electron microscopy, nanoflow analysis, and western blotting. GMSC-exo promoted the proliferation and migration of Madin-Darby canine kidney cells. It was concluded that canine gingiva is a good source of MSCs. Additionally, GMSC-exo is a potentially promising cell-free therapeutic tool for the treatment of canine gingival diseases.

Protection efficacy of the H1 and H3 bivalent virus-like particle vaccine against swine influenza virus infection.

Swine influenza (SI) is widely prevalent in pig herds worldwide, causing huge economic losses to the pig industry and public health risks. The traditional inactivated swine influenza virus (SIV) vaccines are produced in chicken embryos, and egg-adaptive substitutions that occur during production process can impact vaccine effectiveness. Thus, developing an SI vaccine that can decrease the dependence on chicken embryos with a high immunogenicity is urgently needed. In this study, the utility of insect cell-derived SIV H1 and H3 bivalent virus-like particle (VLP) vaccines containing HA and M1 proteins of Eurasian avian-like (EA) H1N1 SIV and recent human-like H3N2 SIV were assessed in piglets. Antibody levels were monitored, and the protection efficacy of the vaccine after viral challenge was evaluated and compared with the inactivated vaccine. Results show that piglets produced high hemagglutination inhibition (HI) titers of antibodies against H1 and H3 SIV after immunization with SIV VLP vaccine. The neutralizing antibody level was significantly higher in SIV VLP vaccine than in the inactivated vaccine at 6 weeks post vaccination (p < 0.05). Furthermore, piglets immunized with the SIV VLP vaccine were protected against the challenge of H1 and H3 SIV, displaying inhibition of viral replication in piglets, and reduced lung damage. These results show that SIV VLP vaccine has good application prospects, thus laying the foundation for further research and commercialization of SIV VLP vaccine.

Protective effect of bivalent H1N1 and H3N2 VLP vaccines against Eurasian avian-like H1N1 and recent human-like H3N2 influenza viruses in a mouse model.

Eurasian avian-like (EA) H1N1 swine influenza viruses (SIVs) are currently the most prevalent SIVs in Chinese swine populations, but recent human-like H3N2 SIV subtypes have also been frequently isolated. Hence, there is an urgent need to develop an effective vaccine against both EA H1N1 and recent human-like H3N2 infections. In this study, we utilized the baculovirus expression system to produce virus-like particles (VLPs) containing hemagglutinin protein (HA) and matrix protein (M1) based on A/Swine/Guangdong/YJ4/2014 (H1N1) and A/swine/Guangdong/L22/2010 (H3N2). An immunological experiment showed that in a mouse model, bivalent VLP vaccines against H1N1 and H3N2 can induce stronger humoral and cellular immune responses than whole influenza virus vaccines. Compared with monovalent inactivated vaccines that cannot offer protection against different SIV subtypes, monovalent H1N1 or H3N2 VLP vaccines can provide partial protection against lethal challenge by viruses of different subtypes. Meanwhile, bivalent VLP vaccines against H1N1 and H3N2 can provide full protection against lethal doses of homologous and heterologous viruses belonging to the EA H1N1 or recent human-like H3N2 lineage. These results suggest a promising approach to the development of vaccines against SIVs.

Production of monoclonal antibody against EP0 protein of pseudorabies virus and determination of its recognized epitope.

Early protein 0 (EP0) is especially important for modulating PRV gene expression and reactivation from the latent state, but the mechanisms have not been elucidated. In this study, six monoclonal antibodies (MAbs) against EP0 protein of PRV were generated and their characterizations were investigated. Western blot analysis showed all six MAbs could react with immunizing antigen, but only 2B12 and 2C6 could react with native EP0 protein from PRV-infected cells. ELISA additivity tests revealed that at least three epitopes in EP0 were defined by six MAbs. The epitope recognized by MAb 2B12 was further identified in 287-292 aa of EP0 protein using a series of expressed overlapping peptides. These MAbs may provide valuable tools for further research of the functions of EP0 in PRV infection.