Optimisation of reverse transcription can improve the sensitivity of RT-PCR for detection of classical swine fever virus

Comparison of PCR methods for detection of classical swine fever virus and other pestiviruses

Classical swine fever (CSF) is a notifiable, highly contagious disease of swine controlled mainly with costly administrative methods. Swine may be infected not only with classical swine fever virus (CSFV), but also with other, non porcine, genetically and antigenically related pestiviruses. Differentiation of infections with CSFV and other pestiviruses is a crucial element of diagnostics. In the present study two real-time PCR methods and conventional one-tube nested PCR for specific detection of CSFV were compared. Additionally, two methods designed for detection of all pestivirus species real-time SYBR Green I and one-tube nested PCR were included into the study. Analyzed methods varied considerably regarding their sensitivity and specificity, what suggests that careful selection of diagnostic methods and their evaluation on a regular basis is necessary.

Linked outbreaks and control of porcine reproductive and respiratory syndrome and postweaning multisystemic wasting syndrome in a pig farm in Poland

In a newly established farrow-to-finish farm (porcine reproductive and respiratory virus [PRRSV]-free, porcine circovirus type 2 [PCV-2]-infected), reproductive failure was seen seven months after population. The conception rate dropped from 89 to 51 per cent, and the abortion rate increased from 0.5 to 11 per cent. The following month, characteristic lesions of postweaning multisystemic wasting syndrome (PMWS) and elevated mortality were observed in weaned pigs. Laboratory examinations confirmed reproductive failure due to PRRSV and PMWS associated with apparent activation of the PCV-2 circulating in the farm. The herd was closed for replacement and a number of measures to improve hygiene, environmental conditions and feeding were applied. The abortion rate returned to preoutbreak levels four months after the beginning of the PRRS outbreak and the conception rate returned to normal four months later. Slower improvement was observed regarding the PMWS outbreak, with PMWS-related losses disappearing nine months after the detection of PMWS. Analysis of seroconversion profiles to PCV-2 and PRRSV during the outbreak and after its control indicated that while PRRSV was eliminated from sows and weaners by the control measures, the time of PCV-2 infection was unchanged and occurred at seven weeks of age during the PMWS outbreak as well as after its elimination. However, the elimination of PMWS from the herd coincided with increased levels of maternally derived antibodies to PCV-2 in one- to five-week-old pigs and faster serological responses to infection with PCV-2.