Genetic profile of African swine fever virus responsible for the 2019 outbreak in northern Malawi
BMC VETERINARY RESEARCH
Authors: Hakizimana, J. N.; Kamwendo, G.; Chulu, J. L. C.; Kamana, O.; Nauwynck, H. J.; Misinzo, G.
Background African swine fever (ASF) is an infectious transboundary animal disease which causes high mortality, approaching 100% in domestic pigs and it is currently considered as the most serious constraint to domestic pig industry and food security globally. Despite regular ASF outbreaks within Malawi, few studies have genetically characterized the causative ASF virus (ASFV). This study aimed at genetic characterization of ASFV responsible for the 2019 outbreak in northern Malawi. The disease confirmation was done by polymerase chain reaction (PCR) followed by molecular characterization of the causative ASFV by partial genome sequencing and phylogenetic reconstruction of theB646L(p72) gene, nucleotide alignment of the intergenic region (IGR) betweenI73RandI329Lgenes and translation of the central variable region (CVR) coded byB602Lgene. Results All thirteen samples collected during this study in Karonga district in September 2019 were ASFV-positive and after partial genome sequencing and phylogenetic reconstruction of theB646L(p72) gene, the viruses clustered into ASFV p72 genotype II. The viruses characterized in this study lacked a GAATATATAG fragment between theI173Rand theI329Lgenes and were classified as IGR I variants. Furthermore, the tetrameric amino acid repeats within the CVR of theB602Lgene of the 2019 Malawian ASFV reported in this study had the signature BNDBNDBNAA, 100% similar to ASFV responsible for the 2013 and 2017 ASF outbreaks in Zambia and Tanzania, respectively. Conclusions The results of this study confirm an ASF outbreak in Karonga district in northern Malawi in September 2019. The virus was closely related to other p72 genotype II ASFV that caused outbreaks in neighboring eastern and southern African countries, emphasizing the possible regional transboundary transmission of this ASFV genotype. These findings call for a concerted regional and international effort to control the spread of ASF in order to improve nutritional and food security.
Vertical transmission of anti-ASFV antibodies as one of potential causes of seropositive results among young wild boar population in Poland
POLISH JOURNAL OF VETERINARY SCIENCES
Authors: Walczak, M.; Frant, M.; Juszkiewicz, M.; Mazur-Panasiuk, N.; Szymankiewicz, K.; Bruczynska, M.; Wozniakowski, G.
The present study attempted to elucidate possible routes leading to the achievement of scro-positive results, among young (aged <= 1 year) wild boar population. In the years 2017-2018. the National Reference Laboratory (NRL) for African swine fever (ASF) in Poland examined nearly 27-thousand wild boar blood samples, collected during an active surveillance of ASF risk zones, for the presence of viral DNA and anti-ASFV antibodies. Out of all the examined samples. 420 were positive. However. in more than half of them (292 samples) antibodies against African swine fever virus (ASFV) were detected, while ASFV DNA was not detected in blood. Out of all 292 seropositive/PCR-negative samples, 126 belonged to young wild boars (aged <= 1 year). For this reason, the NRL in Poland has examined 10 selected seropositive wild boar carcasses to confirm or exclude post-mortem lesions for ASF as well as to investigate the presence of viral DNA in the internal organs. Neither pathological lesions for ASF nor the presence of genetic material of ASFV were found in the examined wild boars. To elucidate this outcomes, following hypotheses about possible reasons of the obtained results were drawn: the presence of convalescent animals, infection of low-virulent ASFV isolate and the vertical transmission of antibodies through the colostrum.