New insights into the genetic diversity, phylogeny, and immunogenic potential of the wsp gene in Wolbachia endosymbionts in Brugia malayi and Brugia pahangi

<i>Wolbachia</i> spp. are intracellular, maternally inherited bacteria that infect a wide range of arthropods. These bacteria influence reproductive traits in their hosts and are used in mosquito-borne virus control programmes. This study investigates the <i>Wolbachia</i> surface protein (WSP), a potential trigger of innate immune responses. The <i>wsp</i> gene was amplified by polymerase chain reaction, cloned, and sequenced. Phylogenetic analysis showed that <i>wsp</i> sequences from <i>Wolbachia</i> endosymbionts of <i>Brugia pahangi</i> and <i>B. malayi</i> formed two clades within the supergroup D. The <i>wsp</i> sequences were highly conserved, with 99-100% sequence identity across global isolates. Haplotype analysis revealed 13 distinct <i>wsp</i> haplotypes. The average antigenic score of the WSP protein was 1.029 for <i>B. malayi</i> and 1.026 for <i>B. pahangi</i>. MHC-NP analysis predicted eight antigen ligands for <i>B. malayi</i> and six for <i>B. pahangi</i>. Notably, a shared antigen ligand (VIADQKHGF) was identified for both species, associated with dog leukocyte antigens (DLA-8850101, DLA-8803401, and DLA-8850801). Additionally, a conserved ligand region (ALVMLLSLSNSAFSD) was identified in the WSP of <i>B. malayi</i>, corresponding to human leukocyte antigens (HLA-DR alleles HLA-DRB1∗04:04 and HLA-DRB1∗04:01). These findings provide new insights into the phylogenetic classification, sequence conservation, and immunogenic potential of the WSP protein in <i>Wolbachia</i> endosymbionts of <i>Brugia</i> spp.