‘Isolation and molecular characterization of camelpox virus from outbreak cases in Borena, Ethiopia
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Date
2025
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Addis Abeba University
Abstract
An outbreak investigation was conducted from October-2024 to May-2025 in Borena Zone, Ethiopia focussing on isolation and molecular characterization of camelpox virus from recent outbreak cases. The study included clinical evaluation, isolation and molecular characterization using PCR, RT-PCR, sequencing and phylogenetic analysis. During clinical investigation camels manifesting typical pox-like lesions, fever and swollen lymph nodes were observed. The outbreak had 33.8% morbidity rate, i.e 24 out of 71 camels were clinically sick, and the case fatality rate was 4.2%, 1 camel out of 24 clinically sick camels died. The study showed successful isolation of the virus using Vero cell line, with typical cytopathic effects such as rounding of cells, syncytia, giant cell formation, aggregation and detachment of cell sheet. The conventional PCR result showed skin scab and nasal swab samples yielded the amplification products of the expected 881bp size, which corresponds to the partial fragment of A-type inclusion protein (ATIP) gene. Specifically, 26.3% of skin scab and 26.3% of nasal swab samples tested positive for camelpox virus genome. The RT-PCR employing HRM assay detected CMLV DNA in ten out of 19 samples (52.6%), with a specific melting temperature of 73.00±0.20 °C for CMLV, and no amplific -ation was observed Capripoxvirus and Parapoxvirus. The molecular characterization and the phylogenetic analysis of the five sequenced isolates of the ATIP gene showed 100% nucleotide similarity with comparable reference CMLV strains of CMLV M-96, CMLV CMS, strain 0408151v and CMLV genome (NC_003391). Despite the overall high similarity, a single nucleotide variations were noted when compared to the previously reported Ethiopian isolates (KU705085-KU705110) and Israeli isolates (MK910851 and MZ300856) at position 448 (A:G). Furthermore, two nucleotides mismatches were observed at positions 6 and 448 (A:G) when aligned with Sudanese isolates (KT931624 and KT931625). The phylogenetic analysis showed that the current isolates of this study clustered with CMLV strains of CMLV M-96, CMLV CMS, strain 0408151v and other, but distinct from previously reported Ethiopian isolates, indicating genetically related but evolutionarily unique viral isolate. This successful isolation and molecular characterization of camelpox virus in Ethiopia provides significant insights on early diagnosis, vaccine development and control strategies.
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Keywords
Camelpox, Camelus dromedary, Ethiopia, Isolation, Molecular characterization