US - Sows previous infected with a relatively mild strain of the Porcine Epidemic Diarrhoea (PED) virus confer protection to their piglets against a more severe strain.
The PED virus has infected approximately 50 per cent of the US swine breeding herds from July 2013 to July 2014 as estimated by the Swine Health Monitoring Project. In the absence of effective vaccines or standard control protocols, there is an urgent need for evidence of cross-protective immune countermeasures.
Researchers at the University of Minnesota have evaluated the response of three-day-old piglets born to sows exposed seven months earlier to a mild strain of PEDv to challenge with a virulent PEDv isolate, reports the American Association of Swine Veterinarians (AASV).
Piglet survival to one week of age was 100 per cent compared to 67 per cent in piglets born to sows not previously exposed, and morbidity was 43 per cent compared to 100 per cent, respectively.
At necropsy at seven days of age, the PEDv Ct value was 23.6 (range 16.6-30.6) in intestinal contents, compared to 17.2 (range 15.9-18.5) (p<0.06) in litters from sows with no previous exposure to PEDv.
The findings indicated that durable lactogenic immunity was present in sows previously exposed to a mild strain of PEDv and this immunity induced cross-protection to representative virulent PEDv. Thus, a naturally attenuated form of PEDv provided significant passive immune protection for seven months against piglet challenge with virulent PEDv.
The paper was published by Goede D., M.P. Murtaugh, J. Nerem, P. Yeske, K. Rossow and R. Morrison. 2014. Previous infection of sows with a "mild" strain of porcine epidemic diarrhea virus confers protection against infection with a "severe" strain; Vet Microbiol. 2014. 31 December. pii: S0378-1135(14)00592-6. doi: 10.1016/j.vetmic.2014.12.019. [Epub ahead of print]
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