Abstract
Background and Aim:Nigeria experienced repeated outbreaks of African swine fever (ASF) in pig herds between 1997 and 2005 in the southwest region of the country. ASF is believed to currently be enzootic in this region. The status of enzootic transmission of ASF virus strain to pigs is; however, unknown. Twenty-three genotypes of the ASF virus based on the p72 gene are found across Africa. This study aimed to identify the current circulating field strain(s) of the ASF virus in Southwest Nigeria and characterized evolutionary trends.Materials and Methods:DNA samples were extracted from 144 pooled blood samples obtained from 2012 to 2013 following the manufacturer’s instructions. DNA was used for conventional polymerase chain reaction using primers targeting the p72 gene and amplified products sequenced with Sanger’s sequencing. Sequences were analyzed for homology and phylogenetic relationships.Results:Eleven of 144 samples (7.6%) showed bands at 950 bp. A new field strain of ASF virus of genotype I that shared ancestry with ASF virus strains or isolates from Spain and Brazil was identified among pig herds. The new strain differs phylogenetically in amino acid composition compared with previously identified ASF virus field strains.Conclusion:The currently circulating field strain of ASF virus suggests a mutation responsible for decreased morbidity and mortality recorded in sporadic cases.
Highlights
African swine fever (ASF) is a highly contagious disease of domestic pigs caused by a DNA arbovirus in the family, Asfarviridae
A new field strain of ASF virus of genotype I that shared ancestry with ASF virus strains or isolates from Spain and Brazil was identified among pig herds
The currently circulating field strain of ASF virus suggests a mutation responsible for decreased morbidity and mortality recorded in sporadic cases
Summary
African swine fever (ASF) is a highly contagious disease of domestic pigs caused by a DNA arbovirus in the family, Asfarviridae. It crosses both local and international borders and may trigger fatal outbreaks, especially in naïve pig herds. Genotype II is reported in Europe, the Caucasus, and recently in China [6] This highly virulent strain caused 100% mortality in pigs and wild boars in Georgia, Caucasus region in 2007 [7]. Nigeria experienced repeated outbreaks of African swine fever (ASF) in pig herds between 1997 and 2005 in the southwest region of the country. This study aimed to identify the current circulating field strain(s) of the ASF virus in Southwest Nigeria and characterized evolutionary trends
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