Utility of automated real-time RT-PCR for the detection of foot-and-mouth disease virus excreted in milkScott M. Reida, Satya Paridaa, Donald P. Kinga, Geoffrey H. Hutchingsa, Andrew E. Shawa, Nigel P. Ferrisa, Zhidong Zhanga, J. Eric Hillertonb and David J. Patona
a Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, United Kingdom
b Institute for Animal Health, Compton Laboratory, Newbury, Berkshire, RG20 7NN, United Kingdom
(Received 16 February 2005; accepted 7 June 2005; published online 13 December 2005)
Abstract - Foot-and-mouth disease virus (FMDV) can be excreted in milk and thereby spread infection to susceptible animals in other holdings. The feasibility of using real-time reverse transcription polymerase chain reaction (rRT-PCR) as a diagnostic tool for detection of FMDV in milk was assessed by studying the excretion of virus from experimentally-infected cattle. Fore- and machine milk samples were collected over a 4-week period from two dairy cows infected with FMDV and from two in-contact cows held in the same pen. The whole, skim, cream and cellular debris components of the milks were tested by automated rRT-PCR and results compared to virus isolation (VI) in cell culture. The onset of clinical signs of FMD in all four cows correlated with viraemia, and the presence of FMDV in other clinical samples. rRT-PCR results matched closely with VI in detecting FMDV in all milk components and generally coincided with, but did not consistently precede, the onset of clinical signs. rRT-PCR detected FMDV in milk up to 23 days post inoculation which was longer than VI. Furthermore, the detection limit of FMDV in milk was greater by rRT-PCR than VI and, in contrast to VI, rRT-PCR detected virus genome following heat treatment that simulated pasteurisation. rRT-PCR was also able to detect FMDV in preservative-treated milk. In conclusion, this study showed that automated rRT-PCR is quicker and more sensitive than VI and can be used to detect FMDV in whole milk as well as milk fractions from infected animals.
Key words: milk / milk components / foot-and-mouth disease virus / real-time RT-PCR / pasteurisation
Corresponding author: Scott M. Reid email@example.com
© INRA, EDP Sciences 2005