Abstract
Background:
Lumpy skin disease virus (LSDV), a double-stranded DNA virus of the genus Capripoxvirus, causes LSD in cattle, leading to significant economic and production losses. In Tanzania, information on the molecular epidemiology of LSDV is limited, as its circulation has only been investigated in the Tanga, Pwani, and Rukwa regions.

Aim:
This study aimed to characterize circulating LSDV strains in Dodoma, Arusha, Manyara, Kigoma, Mwanza, and Mara regions, which are densely populated with cattle in Tanzania, to understand genetic diversity in these areas.

Methods:
Blood and skin biopsy samples (n = 33 each) were collected from 9 districts in Tanzania. Molecular detection was performed by targeting the P32 gene, and genetic variability was assessed by amplifying and sequencing the G protein-coupled chemokine receptor (GPCR) gene. Nucleotide sequences were translated into amino acid sequences using the ExPASy Translate tool, and then both nucleotide and amino acid sequences were aligned, followed by phylogenetic analysis

Results:
Of the 33 blood and 33 skin biopsy samples tested, 20 skin biopsy and 3 blood samples were PCR-positive for LSDV based on the GPCR gene. Multiple sequence alignment revealed nucleotide substitutions (A→C) at positions 10 and 34 and an amino acid substitution (T→P) at position 12 in some Tanzania field isolates, while others exhibited unique amino acid signatures at positions A11, T12, T34, S99, and P199. Phylogenetic analysis demonstrated that the LSDV isolates obtained from Tanzania clustered closely with one another, as well as with reference strains from Africa, Asia, Europe, and Eurasia. Additionally, the Tanzania field isolates formed a different cluster from most reference vaccine strains, suggesting notable genetic variation between circulating field viruses and vaccine-derived strains. However, an exception was observed with the Kenya vaccine strains (KP663708 and KJ818282), which clustered closely with the Tanzania field isolates, indicating a close genetic relationship with these particular vaccine strains.

Conclusion:
Tanzanian LSDV isolates are genetically similar to the reference strains but distinct from most vaccine strains, confirming the circulation of wild-type viruses and highlighting the need for targeted control measures, including monitoring emerging variants and regulating animal movement.

Key words: G protein-coupled chemokine receptor gene; Lumpy skin disease virus; Molecular detection; Phylogenetic analysis; Tanzania.