The Role of Male Reproductive Organs in the Transmission of African Swine Fever—Implications for Transmission

Abstract

African swine fever (ASF) has evolved from an exotic animal disease to a threat to global pig production. An important avenue for the wide-spread transmission of animal diseases is their dissemination through boar semen used for artificial insemination. In this context, we investigated the role of male reproductive organs in the transmission of ASF. Mature domestic boars and adolescent wild boars, inoculated with different ASF virus strains, were investigated by means of virological and pathological methods. Additionally, electron microscopy was employed to investigate in vitro inoculated sperm. The viral genome, antigens and the infectious virus could be found in all gonadal tissues and accessory sex glands. The viral antigen and viral mRNAs were mainly found in mononuclear cells of the respective tissues. However, some other cell types, including Leydig, endothelial and stromal cells, were also found positive. Using RNAScope, p72 mRNA could be found in scattered halo cells of the epididymal duct epithelium, which could point to the disruption of the barrier. No direct infection of spermatozoa was observed by immunohistochemistry, or electron microscopy. Taken together, our results strengthen the assumption that ASFV can be transmitted via boar semen. Future studies are needed to explore the excretion dynamics and transmission efficiency.

Artificial insemination as alternative transmission route for African Swine Fever Virus

“…Previous studies indicated that ASFV did not enter live spermatozoa of spiked boar semen [13], but simultaneous entry of virus and spermatozoa into the ovum cannot be refuted at this point. Attachment of virions to molecules on spermatozoa has been formerly described for other DNA viruses, such as human papilloma virus (HPV, [37]).…”

“…(2021) supported this hypothesis by confirming the presence of both viral genome and infectious virions in gonadal tissue of swine infected with ASFV strains of various genotypes (gt). In these studies, ASFV genome and infectious virions were detected in testes from sexually mature domestic pigs inoculated with Zambian ASFV isolates 'KAB 6/2' (gt XI) and 'SUM 14/11' (gt XIII) [13]. Studies with adolescent wild boar produced similar results for ASFV strains 'Belgium 2018/1' (gt II) and 'Germany 2020' (gt II) [13,14].…”

“…In these studies, ASFV genome and infectious virions were detected in testes from sexually mature domestic pigs inoculated with Zambian ASFV isolates 'KAB 6/2' (gt XI) and 'SUM 14/11' (gt XIII) [13]. Studies with adolescent wild boar produced similar results for ASFV strains 'Belgium 2018/1' (gt II) and 'Germany 2020' (gt II) [13,14].…”

Pathology of African Swine Fever in wild boar naturally infected with German virus variants

“…However, in line with macroscopic findings, histopathology confirmed the severe course of disease in all animals regardless of the outbreak area and the virus variant. Since most wild boar studies focus only on macroscopic pathology, it is even more important to study the histopathology of natural ASF infection in more depth (17, 18, 29, 30).…”

Impact of ASFV Detergent Inactivation on Biomarkers in Serum and Saliva Samples

“…WSL cells were cultivated in Iscove’s Modified Dulbecco’s Medium with Ham’s F-12 Nutrient Mix (Thermo Fisher Scientific, Waltham, MA, USA): 10% FBS, 1% penicillin, and streptomycin (10,000 U/mL; Gibco, Thermo Fisher Scientific, Waltham, MA, USA). Virus isolation and titration on porcine macrophages were carried out with macrophages derived from peripheral blood mononuclear cells (PBMCs) as previously described [ 16 ].…”