Purification and concentration of antigen for ELISA using epizootic isolates of Infectious laryngotrachitis virus isolated in Ukraine

Infectious laryngotracheitis of chickens is one of the most dangerous viral respiratory diseases of chickens, which causes significant economic losses to poultry farms. A key component in this disease control is timely rapid serological diagnosis. To date, the basic method of serological diagnosis and monitoring is enzyme-linked immunosorbent assay (ELISA). The main components of ELISA test systems are purified and concentrated infectious laryngotracheitis virus antigens. Our research aimed to develop a technology for the production of purified and concentrated antigens of infectious laryngotracheitis virus, as well as to test the suitability of epizootic isolates for the production of antigens for ELISA. Based on the results of research, an improved scheme for obtaining purified infectious laryngotracheitis virus antigens using epizootic isolates has been developed. The scheme consists of accumulation of virus raw material, its inactivation, verification of inactivation completeness, concentration of infectious laryngotracheitis virus by PEG-6000 precipitation followed by ultracentrifugation at 14,000 rpm through a 30% sucrose pad. Samples of purified concentrated infectious laryngotracheitis virus antigens from isolates “В 59-11”, “Б 2-10”, “ЧП 96-10”, and “A 4-12” with protein content 1,520–3,720 μg/cm3 have been obtained. The ratio of protein concentration before and after purification ranged from 4.17 to 7.24. ELISA found that all these antigens were suitable for use as antigens. When testing for specificity, it was found that all antigens did not react with heterologous sera to other poultry viral diseases, but reacted only with homologous sera positive for infectious laryngotracheitis, which proves their specificity