Abstract
The pathogenesis mechanisms of Campylobacter fetus subsp. venerealis (Cfv), the etiologic agent of Bovine Genital Campylobacteriosis remain elusive. This study evaluated the virulence potential and biovar characteristics of Cfv isolates (n = 13) by PCR screening of putative virulence-factor (VF) genes, Multilocus Sequence Typing (MLST) analysis, antimicrobial susceptibility to tetracycline, penicillin, enrofloxacin and streptomycin testing and whole-genome sequencing (WGS; n = 5), also comparing the latter with 26 other whole-genome sequences of Cfv strains. The putative VF genes encoding type IV secretion system of Cfv (virB2-virB11/virD4) were absent in 92% of isolates, including isolates from aborted foetuses, evidencing that these VF genes are not essential for Cfv pathogenicity. The parA gene, used as a Cfv diagnostic molecular target, was detected in only 3 of 13 isolates, invalidating its use for diagnosis purposes. Three novel sequence types were identified by MLST. Although no in vitro antimicrobial resistance was detected, WGS identified antimicrobial resistance-related genes, including those encoding the multidrug efflux pumps CmeABC and YkkCD, indicating that their presence is not enough to provide antimicrobial resistance. The SNP and accessory protein families analysis segregated the Cfv and Cfv biovar intermedius (Cfvi) strains into different clusters. In conclusion, this study evidenced virulence potential and biovar characteristics of Cfv and Cfvi, which are of relevance for the control of Bovine Genital Campylobacteriosis.
Highlights
Campylobacter fetus subsp. venerealis (Cfv) is the etiological agent of Bovine GenitalCampylobacteriosis (BGC), a notifiable venereal disease of cattle responsible for low herd reproductive efficiency and significant economic losses worldwide [1,2]
Fic proteins form a toxin–antitoxin network in Cfv that may favor its survival under adverse conditions [15]. These findings indicate a role of this genomic island in Cfv pathogenicity and/or adaptation to the genital tract [10,15]
Cfvsubspecies strains through notypic approaches and uncovered characteristics that aregenomic relevantand for phenotypic approaches and uncovered characteristics of this subspecies that are relevant for Bovine GenitalCampylobacteriosis (BGC) control
Summary
Campylobacter fetus subsp. venerealis (Cfv) is the etiological agent of Bovine GenitalCampylobacteriosis (BGC), a notifiable venereal disease of cattle responsible for low herd reproductive efficiency and significant economic losses worldwide [1,2]. Infected bulls asymptomatically carry Cfv in the preputial and penile mucosa and infect females during natural breeding or through semen, causing embryo loss or early fetal abortion [3]. BGC control is based on bull preputial testing and culling of infected bulls, which requires an accurate identification of Cfv [3,4]. Fetus (Cff ), which colonizes the intestinal tract and occasionally the preputial cavity, causing sporadic abortion in cattle, and Cfv have more than 90% genome similarity [6]. This hampers the selection of suitable molecular targets for subspecies identification
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