Isolation of a non-haemadsorbing, non-cytopathic strain of African swine fever virus in Madagascar

Abstract

African swine fever (ASF) suspected clinically in Madagascar (1998-9) was confirmed by polymerase chain reaction (PCR) and nucleotide sequencing, following virus isolation. No haemadsorption or cytopathic effect could be detected following leukocyte inoculation, but viral growth in cells was confirmed by PCR. Detection of ASF virus genome was carried out by amplification of a highly conserved region coding for the p72 protein. Nucleotide sequencing of the amplicon revealed 99.2% nucleotide identity between the recent Malagasy strains and a virus recovered from the 1994 outbreak in Mozambique (SPEC265). A serological survey performed on 449 sera, revealed that only 5.3% of the sera taken from pigs between 1998 and 1999 were positive.

Comprehensive Phylogenetic Reconstructions of African Swine Fever Virus: Proposal for a New Classification and Molecular Dating of the Virus

“…The TMRCA scale going back to 1700 AD for all ASFV isolates can be considered with confidence since within this scale, the TMRCA of lineage L1-1 and L1-2 were 1943/1955 (for B646L/CP204L genes) and 1990 (for both genes), respectively. L1-1 is supposed to have emerged in the late 1950s [16] and L1-2 includes mainly isolates from Madagascar that were first introduced in 1998 [58]. The substitution rates determined in this study were much higher than expected relative to other large dsDNA viruses like gamma-herpes viruses of vertebrate (10 −9 subs/site/year) or even small dsDNA viruses like the John Cunningham polyomavirus (10 −7 subs/site/year) [55].…”

Related strains of African swine fever virus with different virulence: genome comparison and analysis

“…As referred to above for OURT88/3 (Chapman et al, 2008), NHV is also non-haemadsorbing, with similar deletions as in OURT88/3 for both the lectinlike EP153R and CD2-like EP402R. Haemadsorption is not directly related to virulence, since there are virulent field strains lacking this feature (Gonzague et al, 2001;Pan & Hess, 1984), and deletion of EP402R (8DR) or EP153R (8CR) from Malawi Lil-20/1 did not reduce virulence for domestic pigs, although deletion of 8DR caused a delay in viral spread (Borca et al, 1998;Neilan et al, 1999). Interestingly, haemadsorption enhanced replication in ticks, as observed when it was restored in the NHV strain, but it did not restore virulence for pigs (Rowlands et al, 2009).…”

Molecular epidemiology of African swine fever in East Africa

“…Genotyping techniques based on p72 phylogenetic studies however, do not achieve all the aims of virus molecular typing. This is attested by viruses of different virulence, haemadsorption ability and species of origin, clustering together (Gonzague et al, 2001; Fig. 2.2; Personal communications with diagnostic specimen suppliers).…”