Systemic and intestinal porcine epidemic diarrhea virus-specific antibody response and distribution of antibody-secreting cells in experimentally infected conventional pigs

Yuto Suda,Tomoyuki Shibahara,Seiichi Ohashi,Ayako Miyazaki,Kohtaro Miyazawa

doi:10.1186/s13567-020-00880-z

Abstract

Porcine epidemic diarrhea (PED) is a coronavirus disease characterized by the rapid spread of severe diarrhea among pigs. PED virus (PEDV) infects and replicates mainly in the epithelial cells of the duodenum, jejunum, ileum and colon. Serum or mucosal IgA antibody levels have been used to predict both vaccine efficacy and the level of protective immunity to enteric infectious diseases in individuals or herds. Details of the B-cell immune response upon PEDV infection, such as the systemic and mucosal PEDV IgA antibody response, the distribution of IgA antibody-secreting cells (ASCs), and their role in virus clearance are not yet clear. In this experimental infection study, we observed similar fluctuations in PEDV IgA antibody levels in serum and intestinal contents of the upper and lower jejunum and ileum, but not fecal samples, over the 4-week experimental course. ASCs that actively secrete PEDV IgA antibody without in vitro stimulation were distributed mainly in the upper jejunum, whereas memory B cells that showed enhanced PEDV IgA antibody production upon in vitro stimulation were observed in mesenteric lymph nodes and the ileum. Our findings will contribute to the development of effective vaccines and diagnostic methods for PEDV.

Highlights

Porcine epidemic diarrhea (PED) is an emerging and reemerging swine disease caused by PED virus (PEDV), a member of the family Coronaviridae, genus Alphacoronavirus
All 16 inoculated pigs recovered from the clinical signs, and the amount of detectable fecal PEDV RNA started to decrease after 7 dpi
S/P ratios of serum IgG and IgA and fecal IgA antibody against PEDV Along with the diminished clinical signs and drop in fecal viral RNA shedding, PEDV IgG antibody was detected in the serum of 66.7% (8/12) of inoculated pigs at 7 dpi

Summary

Introduction

Porcine epidemic diarrhea (PED) is an emerging and reemerging swine disease caused by PED virus (PEDV), a member of the family Coronaviridae, genus Alphacoronavirus. PED is characterized by the rapid spread of acute and severe diarrhea within pig herds. Mortality reaches nearly 100% in suckling piglets at susceptible seronegative farms [1–3]. The severity of clinical signs becomes milder and the mortality rate decreases, older pigs are still susceptible to viral infection. After its appearance in 1974, PED caused losses. PEDV is transmitted by the fecal–oral routes and replicates mainly in the epithelium of the small intestine (especially in the jejunum and ileum) and colon [16].

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Conclusion