AK-2011 strain for the development of a vaccine against equine rhinopneumonitis.

Abstract

Equine rhinopneumonitis is an acute, highly contagious disease found virtually worldwide. The purpose of the studies presented in this paper is to develop a technology for the manufacture of a cell-derived equine rhinopneumonitis vaccine, as well as to assess the safety and immunogenicity of the newly developed vaccine in laboratory animals model. The object of the studies was the AK-2011 strain isolated from the horses suffering from rhinopneumonitis during an outbreak of abortions. The viability of the AK-2011 strain was assessed using a continuous line of calf trachea cells, a continuous line of calf kidney cells, a continuous line of sheep kidney cells, a continuous line of bovine kidney cells, a continuous line of green monkey kidney cells, a continuous line of Syrian hamster kidney cells, a primary trypsinized culture of horse kidney cells grown in tubes and flasks and the AK-2011 laboratory strain of equine rhinopneumonitis virus with biological activity of 6.0 lg TCID. Sequencing and polymerase chain reaction analysis were performed. The virus isolated from the ORF68 gene in Kazakhstan appeared to be the most similar to the T-953 and 2222-03 strains isolated in the USA and Australia, respectively, in terms of phylogenetics. As to primary infections, cytopathic effects (CPEs) induced by the AK-2011 virus stain (dilution 10) in calf trachea and horse kidney cell cultures were stable from the first to tenth passages, with biological activity of 5.75-6.00 lg TCID. CPEs caused by the virus were apparent on days 2-3, further developed intensively and extended to 60-80% of the cell monolayer on days 5-7. The vaccine results can be used to immunize horses on farms against rhinopneumonia, and horses should be immunized twice with an interval of 2-3 months.