Possibility of long-term survival of African swine fever virus in natural conditions

Abstract

Background and Aim: In modern scientific literature presents an understanding that African swine fever (ASF) ASF virus (ASFV) is remarkably stable in the environment, and carcasses of the pigs which were died after ASF, play a key role as ASFV reservoir. The aim of this study was to evaluate the possibility of the ASFV (different isolates) survival in bodies of dead animals, bones, remnants of bone marrow, residual organ matrix in natural conditions. Materials and Methods: Skeletons of ASFV infected pigs which were died and left/abandoned in forests or buried in Armenia at diverse time points and locations had been excavated and examined for the presence of ASFV genome by real-time polymerase chain reaction (PCR) assay and for infection abilities through in vitro (hemadsorption test and infection in porcine lung macrophages) as well as by intramuscular infection in healthy pigs. Results: Current exploration showed that in several samples (with different times of exposure) of excavated skeletons had been detected the presence of the virus gene (p72) using real-time PCR. However, in none of these porcine samples, infectious ASFV could be isolated. Data obtained by real-time PCR at frequent intervals indicated the presence of the virus gene (p72), especially within the case of the acute form of the disease. This can be explained by the highest levels of the virus during the latter case mentioned above. Conclusion: ASFV seems to be very sensitive to environmental temperature. The best place for ASFV long-term survival in the natural environment is bone marrow from intact big tubular bones (like femur or tibia) of buried carcasses. In artificial "graves," complete bones with not destructed bone marrow can preserve the virus gene (p72) for a very long time (more than 2 years). Infectious particles in underground conditions survive not so long: In complete bones with not affected bone marrow, possible presence of the virus for several months.

African Swine Fever Survey in a European Context

“…Studies on food habits of wolves indicate that wild boar is their main prey, reaching up to 50% of wolves' diet [47,48]. All experts indicated that predation occurred mainly on piglets or juveniles, being more frequently in spring, although they can also predate during the whole year, as 48% of experts agreed and in line with other studies [43,44]. Two new concerns expressed by experts were the possibility of wild boar increasing movements and range, leading to ASF dispersal because of wolf activities, and the potential overlapping of wolves and other potential predators with wild boar in natural and agroforestry areas.…”

“…On one hand, scavengers reduce the time a carcass remains in the environment, decreasing environmental persistence, but on the other hand, not all carcass remains are removed, and bones in particular will remain [17,43]. ASF virus genome can remain preserved in bones and the remnants of bone marrow of buried carcasses for more than two years [44]. Furthermore, some mammals and birds can transport pieces of meat in their mouths or beaks, contributing to local ASF spread [43].…”

Experimental Evidence of the Long-Term Survival of Infective African Swine Fever Virus Strain Ba71V in Soil under Different Conditions

“…Another highly important characteristic in terms of virus survival is the stability of the virus against proteases and nucleases [1]. The cause of the high resistance of viral particles lies in the extremely complex structure of the virion [10]. ASFV is the sole member of the Asfarviridae family and belongs to the group of large nucleocytoplasmic DNA viruses.…”

A triton X-100 assisted PMAxx-qPCR assay for rapid assessment of infectious African swine fever virus

“…It has been shown that ASFV can remain viable in natural conditions for long time periods ( Arzumanyan et al, 2021 ) and be directly transmitted by complex transmission routes such as contact between infected and susceptible pigs ( Gaudreault et al, 2020 ), consumption of infected pig meat ( Ito et al, 2020 ), and bites from infected acari ( Ornithodoros spp. ; Pereira De Oliveira et al, 2020 ).…”