Development of a reverse transcription-nested polymerase chain reaction assay for differential diagnosis of transmissible gastroenteritis virus and porcine respiratory coronavirus from feces and nasal swabs of infected pigs
L. Kim et al., Development of a reverse transcription-nested polymerase chain reaction assay for differential diagnosis of transmissible gastroenteritis virus and porcine respiratory coronavirus from feces and nasal swabs of infected pigs, J VET D INV, 12(4), 2000, pp. 385-388
Transmissible gastroenteritis virus (TGEV), a coronavirus, replicates in in
testinal enterocytes and causes diarrhea in young pigs. Porcine respiratory
coronavirus (PRCV), a spike (S) gene natural deletion mutant of TGEV, has
a respiratory tissue tropism and causes mild or subclinical respiratory inf
ections. Conventional antigen-based diagnostic tests fail to differentiate
TGEV and PRCV, and a blocking ELISA test to serologically differentiate TGE
V/PRCV-infected pigs is conducted on convalescent serum retrospectively aft
er disease outbreaks. A reverse transcription (RT)-nested polymerase chain
reaction (PCR) with primers targeted to the S gene deletion region to diffe
rentiate TGEV/PRCV was developed. The specificity of the RT-nested PCR was
confirmed with reference and recent field strains of TGEV/PRCV, and its sen
sitivity was analyzed by testing nasal and fecal samples collected from pig
s at various days postinoculation (DPI) with TGEV or PRCV. Specific PCR pro
ducts for TGEV/PRCV were detected only with the homologous reference or fie
ld coronaviruses and for 10-14 DPI of pigs with TGEV (feces) or PRCV (nasal
samples). The RT-nested PCR assay was more sensitive than antigen-based as
says on the basis of duration of virus detection in experimentally infected
pigs and was directly applicable to nasal as well as fecal specimens from
the field.