Development and Field Testing of a Real-Time PCR Assay for Caprine Arthritis-Encephalitis-Virus (CAEV)

Abstract

Caprine arthritis/encephalitis (CAE) of goats and occasionally sheep, are persistent virusud infections caused by a lentivirus (CAEV). This viral infection results in arthritis in adult animalsud and encephalitis in kids. Prognosis for the encephalitic form is normally poor, with substantialud economic loss for the farm. In this context an early/fast laboratory diagnosis for CAEV infectionud could be useful for effective prophylactic action. In this work we performed a quantitative real timeud PCR designed on the CAEV env gene to detect/quantify in goat/sheep samples, viral RNA orud proviral DNA forms of CAEV. This procedure was validated in 15 sheep experimentally infectedud with CAEV or with a high correlated lentivirus ( visna maedi, MVV) ; in addition, a total of 37ud clinical goat specimens recruited in CAEV positive herds were analyzed and compared usingud serological analysis (Elisa and AGID). All samples infected with MVV resulted negative. In sheep,ud experimentally infected with CAEV , proviral DNA was detectable 15 days post infection, whereasud the serological methods revealed an indicative positivity after 40-60 days. This method showed aud sensitivity of 102 env fragments /PCR) with a linear dynamic range of quantitation from 102 to 107ud env fragments/PCR, the correlation coefficient R2 was 0.98. All subjects with clinical diagnosis forud Caprine Arthritis-Encephalitis (CAE) resulted CAEV DNA positive