Alternative approaches to the diagnosis of African swine fever in the Russian Federation in 2017–2021

Introduction. Prevention and control of African swine fever (ASF) transmission on the territory of the Russian Federation requires monitoring based on testing of samples from pigs and wild boars. Specific anti-ASFV antibodies are rarely detected in samples during routine serological diagnostics. Although, ASF isolates with weakened virulence were confirmed in Russia and neighboring countries. The aim of this work was to determine the possibility of using alternative samples for ASF diagnosis and evaluate the effectiveness of the diagnostic methods used on the territory of Russia. Materials and methods. Biological materials obtained from experimentally infected animals and samples collected in the field conditions were used in this study. Results. Complex testing (RT-PCR and ELISA) is a more effective approach to diagnose chronic and asymptomatic forms of ASF compared to the separate use of these techniques. The possibility and efficiency of using alternative samples in diagnostics are demonstrated. It was confirmed that IPT method overcomes ELISA by high diagnostic sensitivity and detection of antibodies on earlier stages in extended range of samples. Anti-ASFV antibodies were detected in domestic and wild pigs in five regions of Russia. Samples from infected pigs that are negative in RT-PCR can be positive for anti-ASFV antibodies. The detection of antibodies in samples from shot wild boars (negative or uncertain in RT-PCR test) suggests the existence of animals surviving ASF infection. Conclusion. The data obtained suggest a revision of the ASF surveillance strategy, by introducing complex diagnostic methods aimed at detection of both the virus genome and anti-ASFV antibodies simultaneously.