Detection of feline calicivirus, feline herpesvirus 1 and Chlamydia psittaci mucosal swabs by multiplex RT-PCR/PCR

A single tube, multiplex reverse transcription (RT)-polymerase chain reacti on (PCR)/PCR assay was developed for detection of feline herpesvirus 1 (FHV 1), Chlamydia psittaci and feline calicivirus (FCV) in cats with upper res piratory tract disease (URTD), incorporating a simple, rapid extraction pro cedure capable of extracting both DNA and RNA. The assay was found to be as sensitive in vitro as simplex assays that have previously been shown to be as sensitive as, or more sensitive than, culture for each pathogen in expe rimentally infected cats. Conjunctival alone or both conjunctival and oroph aryngeal swabs were collected from cats in 104 households with URTD. FHV 1 was detected in 18 (17.3%) and C, psittaci was detected in 12 (11.5%) house holds. The prevalence of C. psittaci was not significantly different to tha t determined using a duplex PCR assay for C. psittaci and FHV 1. The preval ence of FCV was affected by sample storage temperature. Of samples stored a t -70 degreesC, 0/31 were positive for FCV but FCV was detected in 10/73 (1 3.7%) samples stored at 4 degreesC (P = 0.006). Of the samples stored at 4 degreesC, 3/19 (15.8%) conjunctival swabs were positive for FCV and 6/32 (1 8.8%) oropharyngeal/conjunctival swabs were positive for FCV (P = 0.79), Th e potential utility of restriction endonuclease analysis of RT-PCR products resulting from amplification of the hypervariable region of the capsid pro tein gene of FCV in field samples, without prior cultivation, was also exam ined. The assay may have considerable importance for diagnosis and epidemio logical surveys of feline upper respiratory tract pathogens. (C) 2001 Elsev ier Science B,V. All rights reserved.