Serological Detection, Isolation and Molecular Confirmation of Parainfluenza Virus-3 in Camels, Iraq

Abstract

The objectives of this study were to detect and isolate the Parainfluenza-3 virus (PIV-3) in camels with naturally developed respiratory illness and to determine the titer of the isolates using the virus titration. Therefore, an overall 100 nasal swabs and jugular vein blood samples were collected from diseased camels in four districts in Wasit province (Iraq) from December (2019) to March (2020). The swabs were subjected to six subsequent passages on bovine kidney cell culture (BKCC) to isolate the virus and to confirm infection by molecular PCR assay. Fever (40°C), abundant runny nasal discharge, ocular discharge, coughing, depression, increased respiratory rate, abnormal breath sounds, and mainly wheezing are the most observed clinical signs. Positive findings were involved 24% by ELISA and 37% by RT-PCR. The age group from 1-2 years old showed a high infection rate, while the lower level was in the 4-6 years old group. Regarding season, the infection rate was high in winter compared to spring. Sheik Saad city appeared to have a higher infection rate than other districts. The positive samples inoculated into the Bovine kidney cell culture (BKCC) revealed the cytopathic effects (CPE) after three successive passages, which appeared as clumping and rounding with the progression of infection time at the 4th passage. Elongation and giant cell formation were shown in some isolates after the 5th and 6th passages until they reached complete detachments of the cells from the cell sheet. The titer of viral tissue culture infective dose (TCID50) of the 3rd passage was determined in BKCC cells at 10–3/0.05 ml, and the high titer was shown at the 5th and the 6th passages equal to 10-5/ 0.05 ml. In conclusion, PIV-3 is widespread among camels infected with respiratory illness; therefore, studies are necessary to detect the prevalence rate among camels in other Iraqi regions. Keywords: PIV-3, Fusion protein gene, Hemagglutination protein gene, ELISA, PCR