Detection and Sequence Analysis of Toxoplasma Gondii B1 Gene in Tissues of Some Bird Species in Plateau State, Nigeria

Abstract

Toxoplasma gondii is a single-cell parasite capable of infecting almost all homeotherms posing a grave public health risk globally. There is limited available literature on the T. gondii strains circulating in bird species in the Plateau State, of Nigeria. Consequently, this study was carried out to identify and confirm T. gondii infection and also determine the relationship of the DNA sequences with those of bird species in other parts of the world. To achieve this, brain and heart tissues of 25 bird species were sampled and a nested polymerase chain reaction (nPCR) and sequence analyses of the B1 gene were carried out. The DNA of T. gondii was identified in the heart and brain tissues of 7/7 (100.0 %) of wild bird species, and 15/18 (83.3 %) of domestic local chickens (Gallus gallus domesticus) sampled. The evolutionary relationship among the T. gondii sequences in this study using phylogenetic tree constructed by maximum likelihood method showed the sequences shared a common ancestor with the Type I RH strain (GenBank: AF179871). The T. gondii sequences were in a cluster distinct from other sequences in the GenBank. Calculations of genetic differentiation and genetic diversity indices undertaken and collated revealed three haplotypes with higher haplotype diversity within the T. gondii sequences obtained from wild birds (0.667) compared with the sequences from local chickens (0.333). A 97–100 % homology among the aligned sequences of T. gondii in the study shows that only one strain type exists in all of the samples. This study has established the occurrence of T. gondii infection in asymptomatic bird species in the study area and portrays them as carriers, and potential sources of human infection.

Keywords

• bird species
• carriers
• diversity
• haplo-type
• npcr
• parasite
• sequencing