Characterization of anti-porcine epidemic diarrhea virus neutralizing activity in mammary secretions

Abstract

Porcine epidemic diarrhea virus (PEDV) causes a severe clinical enteric disease in suckling neonates with up to 100% mortality, resulting in devastating economic losses to the pork industry in recent years. Maternal immunity via colostrum and milk is a vital source to neonates of passive protection against diarrhea, dehydration and death caused by PEDV. Comprehensive information on neutralizing activity (NA) against PEDV in mammary secretions is critically important for assessing the protective capacity of sows. Therefore, the objectives of this study were to characterize anti-PEDV neutralizing activity in mammary secretions. Anti-PEDV NA was present in colostrum, milk and serum from PEDV-infected sows as determined both by immunofluorescence and ELISA-based neutralizing assays, with neutralization levels higher in colostrum and milk than in serum. The highest NA was observed in colostrum on day 1, and decreased rapidly in milk at day 3, then gradually declined from day 3 to day 19 post-farrowing. Notably, the NA in mammary secretions showed various patterns of decline over time of lactation that may contribute to variation in sow protective capacities. The kinetics of NA decline were associated with total IgA and IgG antibody levels. Neutralizing activity significantly correlated with specific IgA primarily to spike domain 1 (S1) and domain 2 (S2) proteins of PEDV rather than to specific IgG in colostrum. Subsequently, the NA in milk was mainly related to specific IgA to S1 and S2 during lactation.

Assessment of the safety and efficacy of an attenuated live vaccine based on highly virulent genotype 2b porcine epidemic diarrhea virus in nursing piglets

“…We were also able to confirm sufficient levels of anti-PEDV neutralizing and IgA antibodies in the sera of orally primed sows, which were boosted by the K/K vaccination, colostrum at farrowing, and the sera of sows at and after farrowing, as well as representative offspring sera, indicating that nursing piglets were protected by the transfer of maternal immunity via colostrum and milk from immune dams. These results further support the notion that colostrum and milk IgA and PEDV neutralizing antibody titers are correlated for protective immunity against PEDV; thus, the optimal vaccine regimens tend to promote high levels of both antibodies in the lactogenic secretions of vaccinated sows (Lee, 2015(Lee, , 2019Langel et al, 2016;Song et al, 2016).…”

Efficacy of orally administered porcine epidemic diarrhea vaccine-loaded hydroxypropyl methylcellulose phthalate microspheres and RANKL-secreting L. lactis

“…Newborn piglets rely on maternal lactogenic immunity supplied via colostrum and milk (Saif and Jackwood, 1990). Natural infection or oral immunization with live virus can generate sufficient mucosal or lactogenic immunity, whereas intramuscular administration induces a systemic immune response that provides little lactogenic immunity (Song et al, 2016;Chattha et al, 2015). In general, subunit oral vaccines show poor immunogenicity, and although some toxin adjuvants such as cholera toxin and E. coli heat-labile toxin can act as mucosal vaccine adjuvants, obvious safety concerns prevent their use in a clinical setting (Kim et al, 2015).…”

“…Optimal vaccine regimens induce high levels of both types of antibody in the lactogenic secretions of vaccinated sows (Lee, 2015;Langel et al, 2016;Song et al, 2016). Both synthetic and natural polymers, including enteric coated polymers, are being evaluated as vehicles to deliver proteins to the gastrointestinal (GI) tract.…”

A spike-specific whole-porcine antibody isolated from a porcine B cell that neutralizes both genogroup 1 and 2 PEDV strains

“…The ELISA-based PEDV neutralization (SN) assay was performed as previously described with slight modifications (Song et al, 2016). Briefly, Vero E6 cells were seeded in 96-well plates at a density of 6 × 10 3 cells/well and cultured overnight to form a confluent monolayer.…”

“…PEDV S protein is the main determinant of viral cellular tropism and contains the targets recognized by most neutralizing antibodies (Liu et al, 2015;Park et al, 2011). Protection against PEDV infection is primarily mediated through antibodies, especially neutralizing antibodies (Langel et al, 2016;Song et al, 2016;Lee et al, 2015). Isolating PEDV neutralizing antibodies from memory B cells from PEDV infected or vaccinated pigs can be very useful for understanding the neutralizing antibody development in vivo and could facilitate the design of new subunit vaccines.…”