The Immunology of PCVD

More information is becoming available that PCV-2 has an impact on the immune system of the (young-) pig. MSD Animal Health has asked Dr Artur Summerfield to describe the interaction between the PCV-2 virus and the immune system.

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  The immunology of PCV2 diseases (421k)

  Experimental infection of weaned pigs with PCV-2 alone usually does not result in disease. This is consistent with natural PMWS cases, in the field 99% of PMWS cases reported have been found to be associated with co-infections, such as PRRSV, M. hyopneumoniae, bacterial septicemia and pneumonia, influenza and parvovirus. One possible explanation for this could be an increased susceptibility of PCV-2-infected animals to secondary infections as a consequence of immunosupression. Of particular importance are pathological studies of pigs with PMWS describing that severe lesions are always within the primary and secondary lymphoid tissue. The nature of these lesions will certainly result in severe suppression of immune responses.
  This article discusses how PCV-2 has evolved and how PCV-2 alone appears to be inoffensive but its immunomodulating activity together with co-infections and other husbandry factors contribute to the devastating effects of PCVD.
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Enlarged lymph node with white foci from a pig affected by PMWS.