Adaptive immune responses following Senecavirus A infection in pigs.

Adaptive immune responses following Senecavirus A infection in pigs.

J Virol. 2017 Nov 15;:

Authors: Maggioli MF, Lawson S, de Lima M, Joshi LR, Faccin TC, Bauermann FV, Diel DG

Abstract
Senecavirus A (SVA), an emerging picornavirus of swine, causes vesicular disease (VD) that is clinically indistinguishable from foot-and-mouth disease (FMD) in pigs. Many aspects of SVA interactions with the host and the host immune responses to infection, however, remain unknown. In the present study, humoral and cellular immune responses to SVA were evaluated following infection in pigs. We show that SVA infection elicited an early and robust neutralizing antibody (NA) response, which coincided with and was strongly correlated with VP2- and VP3-specific IgM responses. Notably, NA responses paralleled with reduction of viremia and resolution of the disease. Analysis of the major porcine T cell subsets revealed that during the acute/clinical phase of SVA infection (14 days post-infection; pi) T cell responses were characterized by an increased frequency of αβ T cells, especially CD4(+) T cells which were initially detected by day 7 pi and increased in frequency until day 14 pi. Additionally, the frequency of CD8(+) and double-positive CD4(+)CD8(+) T cells (effector/memory T cells) expressing IFN-γ or proliferating in response to SVA-antigen stimulation increased after day 10 pi. Results here show that SVA elicits B and T cell activation early upon infection, with IgM antibody levels being associated with early neutralizing activity against the virus and peak B and T-cell responses paralleling clinical resolution of the disease. The work provides important insights on the immunological events that follow SVA infection in the natural host.ImportanceSenecavirus A (SVA) has recently emerged in swine causing outbreaks of vesicular disease (VD) in major swine producing countries around the world, including the US, Brazil, China, Thailand and Colombia. Notably, SVA-induced disease is clinically indistinguishable from other high consequence VDs of swine such as FMD, swine vesicular disease, vesicular stomatitis and vesicular exanthema of swine. Despite the clinical relevance of SVA caused VD, many aspects of the virus infection biology remain unknown. Here, we assessed host immune responses to SVA infection. Results show that SVA infection elicits early B and T cell responses, with the levels of NA and CD4(+) T cell responses paralleling with reduction of viremia and resolution of the disease. SVA-specific CD8(+) T cells are detected later during infection. A better understanding of SVA interactions with the host immune system may allow the design and implementation of improved control strategies for this important pathogen of swine.

PMID: 29142122 [PubMed - as supplied by publisher]

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