Impact of dietary spray-dried bovine plasma addition on pigs infected with porcine epidemic diarrhea virus

Duffy, Mark A; Chen, Qi; Zhang, Jianqiang; Halbur, Patrick G; Opriessnig, Tanja

In the current study, the PEDV IgG and IgA antibody responses were more rapid in the BovSDP group compared with the PEDV group. Specifically, by dpi 7, 60% of the BovSDP pigs were anti-IgG and Figure 5 . Mean group log 10 amount of PEDV RNA in PCR positive pigs in fecal samples at different days after PEDV infection. An "A" at a given day indicates significant (P < 0.05) different group means. Statistical analysis was performed by one-way ANOVA followed by pairwise testing using the Tukey-Kramer adjustment if P < 0.05. The statistical software used was JMP Pro 11. IgA positive compared with 12.5% of the PEDV pigs. Of note, while systemic IgA antibodies were measured, mucosal IgA levels were not determined, and it is therefore unknown how the addition of the BovSDP affected the gut immunity. In a previous study, a good correlation of IgA levels in serum and feces was found , and as fecal samples and gut mucosa are more difficult to process during routine lab work, serum IgA levels are commonly tested. Explanations for the earlier humoral immune response in the BovSDP group may include acceleration of the clinical course by the dietary supplement; however, a more rapid immune response due to earlier replication of the virus in more pigs unrelated to the diet modification is also possible. Serum anti-PEDV Ig in pig serum has been demonstrated to neutralize infectivity of PEDV (Hofmann and Wyler, 1989) , and bovine plasma could have a similar neutralizing activity, which was not further assessed in this study. Besides the presence of possible neutralizing antibodies in SDP, other plasma compounds such as peptides (Anderson and Anderson, 2002) could contribute to the benefits seen with SDP addition to a diet.