Genetic characterization and therapeutic management of Babesia spp. infecting dogs
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Date
2024-03
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LUVAS Hisar
Abstract
Canine babesiosis is a clinically significant and emerging tick-borne disease caused by
intraerythrocytic protozoa of the genus Babesia. The present study aimed to study the molecular
detection, sequence and phylogenetic analyses, genetic diversity and haplotype network of Babesia
spp. infecting dogs, along with their therapeutic management. During the study period (May 2022 to
April 2023), 216 blood samples were collected from babesiosis suspected dogs from three north Indian
states (Haryana, Rajasthan and Uttar Pradesh) and one union territory (New Delhi). Most common
clinical signs observed in the infected dogs were fever, anaemia, enlarged lymph nodes, inappetence to
anorexia, lethargy, tachypnea and tachycardia. The percent positivity for canine babesiosis by
microscopy and conventional polymerase chain reaction was 12.5 % (27/216) and 27.78 % (60/216),
respectively. Results of PCR assay revealed that B. vogeli was predominant species as it was
incriminated in 48 cases (22.22%), while B. gibsoni was confirmed in only 12 dogs (5.56%).
Phylogenetic analysis based on the 18S rRNA and cyt b genes of B. vogeli revealed the presence of two
genotypes and sub-clades, respectively. Likewise, phylogeny of B. gibsoni based on the B. gibsoni
thrombospondin-related adhesive protein (BgTRAP) and COXI genes suggested the existence of three
genotypes and a monophyletic clade, respectively. Upon sequence analyses of B. vogeli based on the
18S rRNA gene, a higher level of percent identity (97.6-100 %) was documented within genotypes, as
compared to between them (92.5-93.8 %). A relatively low percent identity was noticed within (93.9-
100 %) and between (83.3-88.4 %) B. gibsoni genotypes based on the BgTRAP gene. Furthermore,
extensive sequence conservation was documented in the cyt b and COXI genes of B. vogeli and B.
gibsoni, respectively. A high haplotype and low nucleotide diversities were recorded in the 18S rRNA
gene of B. vogeli, and BgTRAP and COXI genes of B. gibsoni. The location-wise haplotype networks
exhibited geographical clustering between haplotypes of B. vogeli and B. gibsoni. Dogs in general were
found to be infected with the novel haplotypes of B. vogeli and B. gibsoni. Moreover, the population
genetic structure, demographic history and therapeutic management of B. vogeli and B. gibsoni were
also reported. Among risk factors, B. vogeli infection exhibited significant association with nondescript dogs (OR= 27.49; P= 0.044) and lymph node enlargement (OR= 3.33; P= 0.009). Similarly, B.
gibsoni infection exhibited significant association with dogs aged more than four years (P= 0.000) and
males (P= 0.042). Haematological parameters, viz., Hb, TEC, PCV and thrombocyte count, were found
to be significantly decreased in both B. vogeli and B. gibsoni affected dogs (P <0.05). Biochemical
parameters, viz., ALT, TB, DB, IDB and BUN, were found to be significantly increased in canine
babesiosis affected dogs (P <0.05)