Isolation and characteristics of influenza viruses circulating among swine populations in Kazakhstan during 2018–2019

Abstract

Swine influenza is regarded as a highly contagious and acute infection. Swine can serve as a tool for the emergence of new influenza viruses that are potentially dangerous to humans. This paper shows the results of the isolation of influenza virus strains circulating among swine in Kazakhstan during 2018–2019 and the characterization of their biological properties. Biological samples were collected from pigs of 2 to 5 months of age in peasant livestock farms in East Kazakhstan, North Kazakhstan, Almaty, and Pavlodar regions. During the execution of the polymerase chain reaction for 662 collected samples, the genetic material of the influenza virus was found in 3.17 % of cases, of which the influenza A/H1N1 virus RNA was detected in 1.08 % and that of the A/H3N2 virus in 0.30 %. With performing virological studies of the obtained samples, three hemagglutinating agents were retrieved and indicated as influenza A viruses of the H1N1 and H3N2 subtypes. The isolated strains of swine influenza A virus revealed similarities with each other in a number of characteristics (temperature sensitivity of hemagglutinin, rates of adsorption and elution, sensitivity to nonspecific serum inhibitors), but differed in infectious activity. The results achieved in the detection of virus genetic material in the polymerase chain reaction and the data of virological studies confirmed the circulation of influenza A/H1N1 and A/H3N2 viruses among the swine population in different regions of Kazakhstan during 2018–2019. These findings highlight the importance of continuous monitoring of swine influenza viruses for detection of possibility of interspecies transmission of this infectious agent.