African swine fever viruses with two different genotypes, both of which occur in domestic pigs, are associated with ticks and adult warthogs, respectively, at a single geographical site

Abstract

The role of the ancestral sylvatic cycle of the African swine fever virus (ASFV) is not well understood in the endemic areas of eastern Africa. We therefore analysed the ASF infection status on samples collected from 51 free-ranging warthogs (Phacocherus africanus) and 1576 Ornithodorus porcinus ticks from 26 independent warthog burrows at a single ranch in Kenya. Abattoir samples from 83 domestic pigs without clinical symptoms, originating from specific locations with no recent reported ASF outbreaks were included in this study. All samples were derived from areas of central Kenya, where ASF outbreaks have been reported in the past. Infection with ASFV was confirmed in 22 % of O. porcinus pools, 3.22 % of adult warthog serum samples and 49 % of domestic pig serum samples by using p72-based PCR. All of the warthog sera were positive for anti-ASFV antibodies, investigated by using ELISA, but none of the domestic pig sera were positive. Twenty O. porcinus-, 12 domestic pig-and three warthogderived viruses were genotyped at four polymorphic loci. The ASFV isolates from ticks and domestic pigs clustered within p72 genotype X. By contrast, ASF viruses genotyped directly from warthog sera, at same locality as the tick isolates, were within p72 genotype IX and genetically similar to viruses causing recent ASF outbreaks in Kenya and Uganda. This represents the first report of the co-existence of different ASFV genotypes in warthog burrow-associated ticks and adult wild warthogs. The data from this and earlier studies suggest transfer of viruses of at least two different p72 genotypes, from wild to domestic pigs in East Africa.

Genetic Variation among African Swine Fever Genotype II Viruses, Eastern and Central Europe

“…Although the central variable region has proven useful for resolving epidemiologic complexities at the genotype ( 12 ), country ( 13 ), and region levels, additional genome markers are required to determine the origin and to map the spread of closely related ASFV isolates circulating in eastern Europe. Thus, we designed a set of primers, named ECO1A (5′-CCATTTATCCCCCGCTTTGG-3′ binding site 172,270–172,290) and ECO1B (5′-TCGTCATCCTGAGACAGCAG-3′ binding site 172,616–172,626), to amplify a 356-bp fragment located between the I73R and I329L genes and characterized by the presence of TRS ( 14 ).…”

Genetic characterisation of African swine fever viruses from recent and historical outbreaks in Sardinia (1978–2009)

“…Recent studies have demonstrated the value of full p54 gene sequencing for providing additional, intermediate resolution when typing of ASFV viruses [16]. By combining p72, p54 and pB602L (CVR), a high level resolution approach is achieved for viral discrimination [16,17].…”

False positive results using PCR detection method for African swinefever virus in wild boars from northern Romanian hunting zones

“…Moreover, similar findings in eastern Africa have documented a low incidence of detectable serological responses to ASFV infection using the OIE-approved assays in ASFV-positive swine (18,19).…”