A Single Amino Acid Substitution In The Matrix Protein (M51R) Of Vesicular Stomatitis New Jersey Virus Impairs Replication In Cultured Porcine Macrophages And Results In Significant Attenuation In Pigs

Authors: VELAZQUEZ-SALINAS, LAURO - Oak Ridge Institute For Science And Education (ORISE); Pauszek, Steven; HOLINKA, LAUREN - The Jackson Laboratory; Gladue, Douglas; REKANT, STEVEN - Oak Ridge Institute For Science And Education (ORISE); BISHOP, ELIZABETH - US Department Of Agriculture (USDA); STENFELDT, CAROLINA - University Of Kansas; VERDUGO-RODRIGUEZ, ANTONIO - New Mexico State University; Borca, Manuel; Rodriguez, Luis; Arzt, Jonathan

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2020
Publication Date: 5/29/2020
Citation: Velazquez-Salinas, L., Pauszek, S.J., Holinka, L.G., Gladue, D.P., Rekant, S.I., Bishop, E.A., Stenfeldt, C., Verdugo-Rodriguez, A., Borca, M.V., Rodriguez, L.L., Arzt, J. 2020. A single amino acid substitution in the matrix protein (M51R) of Vesicular Stomatitis New Jersey virus impairs replication in cultured porcine macrophages and results in significant attenuation in pigs. Frontiers in Microbiology. https://doi.org/10.3389/fmicb.2020.01123.
DOI: https://doi.org/10.3389/fmicb.2020.01123

Interpretive Summary: Vesicular stomatitis virus (VSV) is a insect-transmitted virus that causes blisters (vesicular) in the mouth and feet of horses, cattle and pig. The disease in cattle and pigs resembles foot-and-mouth disease, a devastating and hihly contagious disease that is not present in North America. Outbreaks of VSV occurring sporadicaly in the southwestern United States at 8-10 year intervals are caused by viruses that have stable life cycles in certain areas of southern Mexico. How the virus reaches the US is not well understood, but previous studies suggest that viruses capable of moving northward into northern Mexico and southwestern US cause more severe disease in animals by blocking the animal's defenses against viral infections. Here we showed that a version of the virus causing outbreaks in the US that was genetically modified to remove its ability of blocking the animal defenses, was highly attenuated in cells and unable to cause severe disease in animals. This information is valuable for the prevention and control of future VSV outbreaks.

Technical Abstract: In this study, we explore the virulence of vesicular stomatitis New Jersey virus (VSNJV) in pigs, to test the hypothesis that it might be determined by the virus ability to modulate innate responses. For this purpose, we developed a mutant of the highly virulent strain NJ0612NME6, containing a single amino acid substitution in the matrix protein (M51R). The M51R mutant of NJ0612NME6 was unable to suppress the transcriptional gene expression associated with the innate immune response both in primary fetal porcine kidney cells and porcine macrophage cultures. Impaired viral growth was observed only in porcine macrophage cultures, indicating that M51 residue is required for efficient replication of VSNJV in this immune cells. Furthermore, when inoculated in pigs by intradermal scarification in the snout, M51R infection was characterized by decreased clinical signs including reduced fever and development of less and smaller secondary vesicular lesions. It also M51R showed decreased levels of viral shedding and absence of RNAemia compared to the parental virus Interestingly, in some cases, vesicular lesions at the inoculation site resemble those produced by parental virus. The ability of the mutant virus to infect pigs by direct contact remained intact, indicating that M51R mutation resulted in a partially attenuated phenotype, unable to disseminate but still capable of causing local lesions and transmitting to sentinel pigs. Collectively, our results show a positive correlation between the ability of VSNJV to counteract the innate immune response in swine macrophage cultures and the level of virulence in pigs, a natural host of this virus. More studies are encouraged to evaluate the interaction of VSNJV with macrophages and other components of the immune response in pigs.