Two South Dakota State University graduate students have been awarded for their work in studying swine viruses.
Lok Raj Joshi and Maureen Fernandes were honored at the Conference of Research Workers in Animal Disease in Chicago. The students, both enrolled in the Department of Veterinary and Biomedical Sciences, work in the laboratory of Diego Diel, an assistant professor in the veterinary and biomedical sciences department.
The students are pursuing graduate degrees in biological sciences. Joshi just completed a master’s degree and is now working on a doctorate specializing in veterinary microbiology. Fernandes is also working toward her doctorate in that field.
Emerging virus causes problems in swine
Joshi earned the American College of Veterinary Microbiologists’ Donald E. Kahn Memorial Award for Outstanding Graduate Student Presentation. His presentation was about his master’s research on Senecavirus A.
Senecavirus A infects swine, leaving small fluid-filled vesicles on their snout and feet and causes lameness in affected animals. While the virus had been present in the United States since the late 1980s, it did not cause many problems to the swine industry until recently. The main concern with SVA is that the disease that it causes is very similar to foot-and-mouth disease, a disease that is not present in the U.S.
The recent surge in the number of SVA cases reported in the U.S. raised several questions about the virus, including why it re-emerged and how the virus is causing disease. Some of these questions were addressed by Joshi’s research. Joshi participated in two studies to better understand the characteristics of Senecavirus A and to define the ways the virus causes disease.
In the study Joshi presented at the CRWAD meeting, he infected healthy pigs with SVA to study the mechanisms underlying the disease. The animals inoculated in this study developed several vesicular lesions, confirming the etiologic role of Senecavirus A on vesicular disease in pigs. Joshi said the virus was found in several tissues, but was most frequently found in the tonsil of infected animals.
He said that the infected animals began producing antibodies to fight the virus after five days, and typically recovered within two weeks.
Understanding the mechanisms of viral interactions with host immune responses
At CRWAD, Fernandes received first place in poster presentation award given by the American Association of Veterinary Immunologists Awards.
The study she presented evaluated the role of B- and T-cell epitopes on protection against porcine reproductive and respiratory syndrome virus, a common swine virus that causes millions of dollars in losses every year to the swine industry. Fernandes’ study focused on evaluating the potential contribution of small regions of PRRSV proteins (epitopes) on protection against PRRSV infection and disease.
According to Fernandes, there are other ways to manage PRRSV, but researchers are still searching for safer and more efficacious vaccines to induce immunity to the virus. B- and T-cell epitopes have been known to help, but their capacity of producing a protective immune response is unknown.
In the study, pigs were immunized with two constructs, one containing B-cell epitopes and the other with T-cell epitopes. Animal responses were measured and the protective efficacy was evaluated after infection with PRRSV. Despite detectable levels of antibodies against B-cell epitopes, the animals were not protected against PRRSV. These results suggest that despite being targeted by the immune system, these epitopes and the respective immune responses may not contribute for protection against PRRSV.
Fernandes said that PRRSV is a complex virus and the study provided important insights about the virus interactions with the pig immune system. Additional studies are current underway to evaluate the immune responses elicited against the T-cell epitopes.