Genetic Characterization of African Swine Fever Viruses from a 2008 Outbreak in Tanzania

Abstract

Outbreaks of African swine fever (ASF) have been reported in the past from several countries in sub-Saharan Africa. The aim of this study was to genotype ASF viruses (ASFVs) from the 2008 outbreak in Morogoro and Dar es Salaam regions of Tanzania. Tissue samples from domestic pigs that died as a result of severe haemorrhagic disease were collected and analysed with PCR and genome sequencing methods using ASFV-specific primer sets. Nucleotide sequence data were obtained for the B646L (p72), E183L (p54) and the variable region of the B602L gene sequences. Phylogenetic analyses based on DNA sequences showed that the 2008 Tanzanian isolates belonged to p72 genotype XV and clustered together with those derived from the 2001 outbreak in Tanzania. Analysis of the tetrameric amino acid repeat regions within the variable region of the B602L gene showed that the repeat signature of the 2008 Tanzanian ASFV was unique and contained three novel tetramers (U = NIDT/NTDT and X = NTDI). Epidemiological investigation suggested that transportation of live pigs continues to play an active role in the epidemiology of ASF in Tanzania. It is recommended that future control of ASF spread in Tanzania should focus on the early detection and confirmation of the disease, prompt institution of quarantine measures, culling and proper disposal of infected and in-contact animals and decontamination of affected premises.

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

“…New variants are not easy to characterize because of the lack of sequence data from their parent lineage. For example, TAN/08/Mazimbu isolate collected in Tanzania in 2008 and originally placed in genotype XV [52] constitutes in this study a sub-lineage of L3. Thus, it should not be considered as a re-emergence of the TAN/01/1 isolate collected during an outbreak in Tanzania in 2001.…”

“…L3 includes genotypes VIII, XI, XII, XIII, XV, and XVI and one isolate TAN/08/MAZIMBU, previously included within genotype XV [52]. L4 gathers genotypes IX and X. Interestingly, the NYA/1/2 isolate ascribed to genotype XIV is the only isolate that does not segregate within one of the four lineages.…”

Identification of a New Genotype of African Swine Fever Virus in Domestic Pigs from Ethiopia

“…This rich genetic diversity is promoted through the sylvatic cycle and extended by the domestic cycle with open borders and unrestricted movement of swine in conflict areas. Several studies have assessed the role of cross border pig movements and related them to the occurrence of ASF outbreaks within the borders of several countries such as Zambia, South Africa, Mozambique, Tanzania, Kenya and Uganda (Lubisi et al., ; Boshoff et al., ; Gallardo et al., , ,b; Misinzo et al., ; Atuhaire et al., ). Thus, genotypes that were once thought to be specific to one country are now being detected in neighbouring countries.…”

African Swine Fever Virus, Tanzania, 2010–2012

“…As of July 2012, ASF was reported again in the Mbeya and Iringa regions, from which it had been eliminated. This unique ASF outbreak in Tanzania persistently circulated for more than a year; previous outbreaks have been sporadic and resolved after shorter durations ( 8 – 10 ). …”