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.
Transmissible gastroenteritis virus (TGEV), a coronavirus, replicates in intestinal 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 infections. Conventional antigen-based diagnostic tests fail to differentiate TGEV and PRCV, and a blocking ELISA test to serologically differentiate TGEV/PRCV-infected pigs is conducted on convalescent serum retrospectively after disease outbreaks. A reverse transcription (RT)-nested polymerase chain reaction (PCR) with primers targeted to the S gene deletion region to differentiate TGEV/PRCV was developed. The specificity of the RT-nested PCR was confirmed with reference and recent field strains of TGEV/PRCV, and its sensitivity was analyzed by testing nasal and fecal samples collected from pigs at various days postinoculation (DPI) with TGEV or PRCV. Specific PCR products for TGEV/PRCV were detected only with the homologous reference or field 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 assays 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.
Kim
L
L
Department of Veterinary Preventive Medicine, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691, USA.
Chang
K O
KO
Sestak
K
K
Parwani
A
A
Saif
L J
LJ
D000818:Animals; D018352:Coronavirus Infections / Q000175:diagnosis / Q000662:veterinary*; D003937:Diagnosis, Differential; D005243:Feces / Q000821:virology; D005761:Gastroenteritis, Transmissible, of Swine / Q000175:diagnosis*; D017817:Nasal Lavage Fluid; D012141:Respiratory Tract Infections / Q000175:diagnosis / Q000662:veterinary*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary*; D012680:Sensitivity and Specificity; D013552:Swine; D005760:Transmissible gastroenteritis virus