Molecular detection and phylogenetic analysis of Lumpy skin disease virus from outbreaks in Uganda 2017-2018

Abstract

Background Lumpy skin disease (LSD) is an infectious viral disease of cattle caused by a capripox virus. LSD has substantial economic implications, with infection resulting in permanent damage to the skin of affected animals which lowers their commercial value. In Uganda, LSD is endemic and cases of the disease are frequently reported to government authorities. This study was undertaken to molecularly characterize lumpy skin disease virus (LSDV) strains that have been circulating in Uganda between 2017 and 2018. Secondly, the study aimed to determine the phylogenetic relatedness of Ugandan LSDV sequences with published sequences, available in GenBank.Results A total of 7 blood samples and 16 skin nodule biopsies were screened for LSDV using PCR to confirm presence of LSDV nucleic acid. PCR positive samples were then characterised by amplifying the GPCR gene. These amplified genes were sequenced and phylogenetic trees were constructed. Out of the 23 samples analysed, 15 were positive for LSDV by PCR (65.2%). The LSDV GPCR sequences analysed contained the unique signatures of LSDV (A11, T12, T34, S99, and P199) which further confirmed their identity. Sequence comparison with vaccine strains revealed a 12bp deletion unique to Ugandan outbreak strains. Phylogenetic analysis indicated that the LSDV sequences from this study clustered closely with sequences from neighboring East African countries and with LSDV strains from recent outbreaks in Europe. It was noted that the sequence diversity amongst LSDV strains from Africa was higher than diversity from Eurasia.Conclusion The LSDV strains circulating in Uganda were closely related with sequences from neighboring countries. Comparison of GPCR gene showed that vaccine strains were not responsible for outbreaks. This means that vaccination with the currently used vaccine will probably be effective for the control of LSD in Uganda. This information is necessary to understand LSDV molecular epidemiology and to contribute knowledge towards the development of more appropriate control strategies by the Government of Uganda.