The Correlation between Sows and Their Piglets Relating to Immunity Against the Porcine Epidemic Diarrhea Virus

Porcine Epidemic Diarrhea (PED) is caused by PED virus (PEDV) that is a member of the order Nidovirales, family Coronaviridae and genus Coronavirus. PED is a severe enteric disease that causes economic losses worldwide. Maternal passive immunity can prevent losses in suckling piglets during the period of immature immune system. Sow colostrum is the most abundant and easily accessible resource of a farm. The aim of this study was to evaluate an immunological correlation between sow and their offspring.

Forty three sows within parities 1, 3 and 5 were selected from 4 different Thai pig farms; a PEDV free farm (A), a farm which was previously infected with PEDV and PED vaccination was applied in sows (B) and two farms which were previously infected with PEDV and feedback technique for PEDV was applied in sows at 4 weeks before farrowing (C and D). Blood and colostrum samples were collected from these sows at parturition as well as blood samples of their piglets at 5 days old. Sow’s blood samples were collected from jugular veins whereas colostrum samples were collected from the first teat within 30 min post-parturition. All samples were analysed for specific PED immunoglobulin A (IgA) and immunoglobulin G (IgG) using an in-house PED ELISA test kit which was developed by the Diagnostic Unit, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen campus, Thailand. The data was analysed the immunity correlation by using statistical R-program.

For farm A, very low S/P ratios (negative results) of both IgG and IgA in sow’s colostrum and serum were detected. The S/P ratios of IgG in serum and colostrum in vaccinated herd were higher than those in feedback herds. On the other hand, feedback herds had higher S/P ratios of IgA in serum and colostrum. As a result, the S/P ratios of IgG and IgA between sow serum and colostrum showed a positive correlation (r=0.75 and 0.61, respectively). In addition, sow colostrum IgA showed S/P ratio approximately 1.5-2.0 times more than S/P ratio of piglet’s serum IgA at 5 days old. The S/P ratios of IgG and IgA in sow’s colostrum were found to have a positive correlation to those in piglet’s serum (r= 0.72 and 0.71, respectively).

The in-house PED ELISA test kit can be applied to check IgA and IgG in serum and colostrum. The feedback technique induces the higher level of IgA in colostrum. Piglets from sows with high PED immunity in colostrum also have high PED titer in serum. In conclusion, endemically PEDinfected farms must immunize with a suitable technique for a high level of immunity against PEDV and they should focus on piglet colostrum intake management.

Disclosure of Interest: None Declared.