1. Symptomatic and asymptomatic cases of African swine fever in Tanzania
- Author
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Charles Euloge Lamien, Tirumala B. K. Settypalli, Charles Mayenga, Giovanni Cattoli, Bishop Magidanga, Jenna Elizabeth Achenbach, Jelly S Chang'a, Aloyce Kamigwe, Mashaka Jeremiah, Denis Kalabi, Furaha Mramba, Julius J. Mwanandota, and Shukuru Guo
- Subjects
Genotype ,Swine ,040301 veterinary sciences ,Sus scrofa ,Virulence ,Genome, Viral ,Polymerase Chain Reaction ,Tanzania ,Asymptomatic ,African swine fever virus ,Virus ,Disease Outbreaks ,0403 veterinary science ,Rabbit haemorrhagic disease ,03 medical and health sciences ,Intergenic region ,medicine ,Animals ,African Swine Fever ,Phylogeny ,030304 developmental biology ,0303 health sciences ,Base Sequence ,General Veterinary ,General Immunology and Microbiology ,biology ,Outbreak ,Sequence Analysis, DNA ,04 agricultural and veterinary sciences ,General Medicine ,biology.organism_classification ,African Swine Fever Virus ,Virology ,Asymptomatic Diseases ,DNA, Intergenic ,medicine.symptom ,Sequence Analysis - Abstract
African swine fever (ASF) is an acute, highly contagious and deadly viral haemorrhagic disease of domestic pigs caused by African swine fever virus (ASFV). In ASF endemic countries, there are an increasing number of reports on circulating ASFV strains with different levels of virulence causing a broad range of clinical symptoms in susceptible animals. Tanzania, where ASFV is endemic since 2001, recorded several outbreaks including symptomatic and asymptomatic cases between 2015 and 2017. We collected 35 clinical samples from four outbreaks for diagnostic confirmation and sequenced the partial B646L (p72), the full E183L (p54) gene, the central variable region of the B602L gene and the intergenic region between the I73R and I329L genes to characterize molecularly the new ASFV isolates and analyse their relatedness with previously reported Tanzanian and foreign isolates. We detected ASFV in 21 samples, 15 from symptomatic and six from asymptomatic pigs. Phylogenetic analyses based on the partial p72 gene and the complete p54 (E183L) genes revealed that the ASFVs in samples from symptomatic pigs belonged to genotypes II and those in samples from asymptomatic pigs belonged to genotype IX. The CVR profiles of the p72 genotype II and genotype IX isolates differed between each other and from previously published Tanzanian sequences. The sequence analysis of the intergenic region between the I73R and I329L for the 2017 genotype II isolates showed the absence of one GGAATATATA motif in those isolates. This study showed the simultaneous circulation of two different ASFV genotypes with different levels of pathogenicity in Tanzania. Since the existence of sub-clinically infected pigs may contribute to the persistence of the virus, our findings suggest continuous surveillance and characterization of ASFV isolates in disease-endemic regions.
- Published
- 2019