Indian Journal of Comparative Microbiology, Immunology and Infectious Diseases
Year : 2009, Volume : 30, Issue : 1
First page : ( 11) Last page : ( 14)
Print ISSN : 0790-9320. Online ISSN : 0974-0147.

Biological characterization of Indian isolates of infectious bronchitis virus

Bhuvaneshwari T., Singh S.D.*, Dash B.B., Dhama K.

Avian Disease Section, Division of Pathology, Indian Veterinary Research Institute, Izatnagar - 243 122 (U.P.)

*Corresponding author: e.mail - sdsingh2005@rediffmail.com

Abstract

Four field isolates of Infectious Bronchitis Virus (IBV) from different geographical origin were adapted in 9–10 day-old embryonated chicken eggs (ECE). The isolates India/627/AD/02, India/744/AD/04, India/764/AD/04 and India/16/V/AD/07 were subjected to different passage levels to appreciate the characteristic lesions of IBV. The embryos appeared curled with deformed feet and compressed over the head. The amnion was thickened, yolk sac shrunken and membranes were fragile with increased volume of clear allantoic fluid indicating the growth of virus in eggs. Urate deposition in eggs infected with isolates India/764/AD/04 and India/16/V/AD/07 was noticed. The titration of four IBV isolates in ECE revealed that, all the virus isolates grew moderate to high titres in eggs. The EID₅₀ titre of four IBV isolates viz. India/627/AD/02, India/744/AD/04, India/764/AD/04 and India/16/V/AD/07 ranged from 10^5.3 to 10^6.4 EID₅₀. The EID₅₀ titre of India/627/AD/02 isolate was higher than other isolates used in the present study indicating, the EID₅₀ titre increases when the isolates were egg adapted after ten passages. The HA activity in allantoic fluid collected after 10^th passage in all the isolates yielded HA titre ranging 1:16 to 1:64. Further the virus was confirmed by performing HI test using the isolated virus as the antigen with known IBV positive serum. The serum neutralization test which was performed in 9-day-old ECE with the antiserum raised against the standard vaccine strain Massachusetts M41 revealed the neutralization index (NI) ranged from 2.1 to 5.7 and the isolate India/744/AD/04 having the NI of 2.1 with a conclusion of evidence for antigenic variation among the various Indian isolates.

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