Expanding the knowledge frontier of population genetics of Babesia vogeli based on the mitochondrial cytochrome b gene
Introduction: Canine babesiosis is a tick-borne disease caused by intra-erythrocytic apicomplexan protozoans of the genera Babesia throughout the globe. The current study aimed to elucidate the sequence, phylogenetic and haplotype analyses, along with the genetic diversity, demographic history and p...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-03-01
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| Series: | International Journal of Infectious Diseases |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1201971224006623 |
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| Summary: | Introduction: Canine babesiosis is a tick-borne disease caused by intra-erythrocytic apicomplexan protozoans of the genera Babesia throughout the globe. The current study aimed to elucidate the sequence, phylogenetic and haplotype analyses, along with the genetic diversity, demographic history and population-genetic structure of B. vogeli based on all available cytochrome b (cyt b) gene sequences (≥ 685 bp) in GenBankTM. Methods: Species level identification of the Indian large Babesia spp. (n= 21) using single-step PCR assays based on the 18S rRNA gene was performed. It was followed by the PCR amplification, sequencing and molecular analysis of the B. vogeli cyt b gene and protein. Results: The phylogenetic trees constructed using the nucleotide and amino acid sequences placed all the sequences of B. vogeli in one large monophyletic clade; however, it was further divided into two small subclades with high bootstrap values (>95%), hitherto designated as Bv1 and Bv2. All the isolates from each country clustered together in close vicinity with each other, indicating a geographical sub-structuring in the B. vogeli populations. Nucleotide and amino acid sequences exhibited 99.0-100% and 98.7-100% similarity among themselves, respectively. The Bv1 and Bv2 subclades revealed 99.0 and 100% nucleotide, and 98.7% and 100% amino acid similarity between and within them, respectively. No nucleotide variations were observed within Bv1 and Bv2 subclades; but sequence variations were observed at seven places (G92A, C170T, G324A, C438A, G465A, T488C and A659G) between them. Out of these mutations, four were synonymous (G92A, C170T, T488C and A659G), and three were non-synonymous (G324A, C438A and G465A) resulting in amino acid substitutions at three places (V108I, L146I and V155I). Within different B. vogeli populations, the nucleotide and haplotype diversities were low. The median-joining haplotype network displayed only two haplotypes (Hap_1 and Hap_2). The major haplotype, Hap_1, was recorded from India, China and USA; whereas, the minor haplotype (Hap_2), represented by the two newly generated sequences (OR577231 and OR577243), was documented only from India. The statistically significant pairwise genetic distance between the Indian and Chinese populations indicated a moderate genetic differentiation (FST = 0.05; P < 0.05). Contrary to the FST index, a very high gene flow (Nm = 4.75) was recorded between these populations. Neutrality tests and mismatch distributions for the Indian population and overall dataset of B. vogeli indicated a constant population size. Discussion: Genetic characterization of the cyt b gene established it as a useful genetic marker to study the genetic diversity, evolution and relationship among isolates. Conclusion: This is the first report providing an insight into the genetic characterization, population genetics and haplotype network of B. vogeli based on the cyt b gene. |
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| ISSN: | 1201-9712 |