Detection of bovine rotavirus in neonatal calf diarrhoea by elisa, fat and transmission electron Microscopy

The present study was designed to investigate and compare the sensitivity of enzyme linked immunosorbent assay (ELISA), fluorescent antibody test (FAT) and transmission electron microscopy (TEM) for the detection of bovine rotavirus during neonatal calf diarrhea. A total of 112 faecal samples of diarrhoeic calves below three months were collected from organized dairy farms of Namakkal (Tamil Nadu) and Bareilly (Uttar Pradesh), India. Out of these, 27 faecal samples (24.10%) were found positive for rotavirus by ELISA and TEM. The percent positivity ranged from 18.86 % to 55.55% in different organized farms. The rotavirus samples when subjected to isolation in MDBK cells resulted in successful isolation of bovine group A rotavirus in twenty samples. The characteristic cytopathic effects (CPE) were observed from second passage onwards and comprised of clumping and rounding of infected cells, detachment of monolayer, intracytoplasmic eosinophilic inclusions, syncytia and leaving empty vacuole space in MDBK cell line. Rotavirus antigen in cell culture adapted virus was detected by direct fluorescent antibody test (dFAT). The sensitivity and specificity of ELISA and TEM were 100% and 92.32% respectively, considering virus isolation followed by dFAT as standard test. Study indicates that ELISA is most suitable and sufficient test for routine diagnosis of bovine rotaviral as compared to laborious TEM analysis for diarrheic samples; however, isolation of the virus in cell culture remains indispensable for the identification of doubtful specimens. To our knowledge, this is the first report from India employing TEM, ELISA and cell culture based FAT for detection and comparison of these tests for bovine rotavirus group A from diarrhoeic calves.