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BACKGROUND: Bovine genital campylobacteriosis (BGC) is caused by Campylobacter fetus subsp. venerealis (Cfv) including its biovar intermedius (Cfvi). This sexually transmitted disease induces early reproductive failure causing considerable economic losses in the cattle industry. Using a collection of well-characterized isolates (n = 13), C. fetus field isolates (n = 64) and saprophytic isolates resembling Campylobacter (n = 75) obtained from smegma samples of breeding bulls, this study evaluated the concordance of the most used phenotypic (H2S production in cysteine medium and 1% glycine tolerance) and molecular (PCR) methods for the diagnosis of BGC and assessed possible cross-reactions in the molecular diagnostic methods. RESULTS: Characterization at the subspecies level (fetus vs. venerealis) of C. fetus isolated from bull preputial samples using phenotypic and molecular (PCR targeting nahE and ISCfe1) methods showed moderate concordance (κ = 0.462; CI: 0.256-0.669). No cross-reactions were observed with other saprophytic microaerophilic species or with other Campylobacter species that can be present in preputial samples. Whole genome sequencing (WGS) of discrepant isolates showed 100% agreement with PCR identification. For the differentiation of Cfv biovars, comparison of the H2S test (at 72 h and 5 days of incubation) and a PCR targeting the L-cysteine transporter genes showed higher concordance when H2S production was assessed after 5 days (72 h; κ = 0.553, 0.329-0.778 CI vs. 5 days; κ = 0.881, 0.631-1 CI), evidencing the efficacy of a longer incubation time. CONCLUSIONS: This study confirmed the limitations of biochemical tests to correctly identify C. fetus subspecies and biovars. However, in the case of biovars, when extended incubation times for the H2S test (5 days) were used, phenotypic identification results were significantly improved, although PCR-based methods produced more accurate results. Perfect agreement of WGS with the PCR results and absence of cross-reactions with non-C. fetus saprophytic bacteria from the smegma demonstrated the usefulness of these methods. Nevertheless, the identification of new C. fetus subspecies-specific genes would help to improve BGC diagnosis.
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Infecções por Campylobacter , Doenças dos Bovinos , Bovinos , Animais , Masculino , Campylobacter fetus/genética , Infecções por Campylobacter/diagnóstico , Infecções por Campylobacter/veterinária , Infecções por Campylobacter/microbiologia , Espanha , Sequenciamento Completo do Genoma/veterinária , Genitália , Doenças dos Bovinos/diagnóstico , Doenças dos Bovinos/microbiologiaRESUMO
BACKGROUND: Bovine Genital Campylobacteriosis (BGC), a worldwide distributed venereal disease caused by Campylobacter fetus subsp. venerealis (Cfv), has a relevant negative economic impact in cattle herds. The control of BGC is hampered by the inexistence of globally available effective vaccines. The present in silico study aimed to develop a multi-epitope vaccine candidate against Cfv through reverse vaccinology. RESULTS: The analysis of Cfv strain NCTC 10354 proteome allowed the identification of 9 proteins suitable for vaccine development. From these, an outer membrane protein, OmpA, and a flagellar protein, FliK, were selected for prediction of B-cell and T-cell epitopes. The top-ranked epitopes conservancy was assessed in 31 Cfv strains. The selected epitopes were integrated to form a multi-epitope fragment of 241 amino acids, which included 2 epitopes from OmpA and 13 epitopes from FliK linked by GPGPG linkers and connected to the cholera toxin subunit B by an EAAAK linker. The vaccine candidate was predicted to be antigenic, non-toxic, non-allergenic, and soluble upon overexpression. The protein structure was predicted and optimized, and the sequence was successfully cloned in silico into a plasmid vector. Additionally, immunological simulations demonstrated the vaccine candidate's ability to stimulate an immune response. CONCLUSIONS: This study developed a novel vaccine candidate suitable for further in vitro and in vivo experimental validation, which may become a useful tool for the control of BGC.
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Infecções por Campylobacter , Doenças dos Bovinos , Vacinas , Animais , Bovinos , Infecções por Campylobacter/prevenção & controle , Infecções por Campylobacter/veterinária , Vacinologia , Epitopos de Linfócito T/química , Genitália , Biologia Computacional , Doenças dos Bovinos/prevenção & controleRESUMO
Bovine genital campylobacteriosis (BGC) and bovine trichomonosis (BT) are sexually transmitted diseases (STDs) that affect bovine breeding herds, decreasing their reproductive efficiency. The objective of this work was to estimate the prevalence of these diseases and their temporal-spatial distribution in the province of Formosa, Argentina. The cross-sectional study conducted between 2018 and 2021 included a total of 15,571 bulls, inter-herd prevalence being 29.62% and 17.23% for BGC and BT, respectively. The prevalence of positive animals was 2.05% for BGC and 0.43% for BT. The temporal-spatial analysis of BGC showed two distinct spatial groupings, one group had a low risk of contracting the disease (RR = 0.13; p < 0.001; 2018-2021) while the other group had a high risk (RR = 2.84; p < 0.001; 2020-2021). BT had a high-risk group for the disease (RR = 35.24; p < 0.001; 2019). This study shows that STDs are endemic in the region, providing updated and valuable information as a tool for the health management of these diseases.
RESUMO
BACKGROUND: Campylobacter fetus subsp. venerealis (Cfv) is the pathogen responsible for Bovine Genital Campylobacteriosis (BGC), a venereal disease of cattle associated with impaired reproductive performance. Although several PCR assays were developed to identify this pathogen, most of them are still poorly evaluated in clinical samples. This study evaluated real-time PCR assays for Cfv detection in preputial samples of bulls (n = 308). RESULTS: The detection at the subspecies level (Cfv) compared four assays: two targeting ISCfe1 and two targeting parA gene. The detection at the species level (C. fetus) considered an assay targeting the nahE gene and a commercial kit for C. fetus identification. At the subspecies level, assays directed either to different targets (parA and ISCfe1), or to the same target (ISCfe1 or parA), showed a high percentage of disagreeing results. All samples positive at the subspecies level (n = 169) were negative in C. fetus detection assays, which strongly suggests the horizontal gene transfer of ISCfe1 and parA to other bacterial species. This was confirmed by microbiological isolation of three Campylobacter portucalensis strains responsible for false positive results. Sequences with a high level of identity with ISCfe1 and parA gene of Cfv were identified in C. portucalensis genome. CONCLUSIONS: Overall, this study reveals that PCR assays solely directed to a subspecies target originate a high rate of false positive results, due to the presence of parA and ISCfe1 homologous sequences in other bacterial species, namely of the genus Campylobacter. Although the specificity of these methods may be higher if applied to bulls from herds with clinical features of BGC or in other geographical regions, current PCR diagnosis should couple subspecies and species targets, and further research must be envisaged to identify Cfv specific molecular targets.
Assuntos
Infecções por Campylobacter/veterinária , Campylobacter/isolamento & purificação , Doenças dos Bovinos/diagnóstico , Doenças dos Bovinos/microbiologia , Animais , Técnicas de Tipagem Bacteriana/veterinária , Campylobacter/genética , Infecções por Campylobacter/diagnóstico , Infecções por Campylobacter/microbiologia , Bovinos , Prepúcio do Pênis/microbiologia , Masculino , Reação em Cadeia da Polimerase em Tempo Real/veterináriaRESUMO
Bovine genital campylobacteriosis caused by Campylobacter fetus subsp. venerealis (Cfv) is of considerable economic importance to the cattle industry worldwide. Cfv causes syndrome of temporary infertility in female cattle, early embryonic mortality, aberrant oestrus cycles, delayed conception, abortions and poor calving rates. In the present study, a total of 200 samples obtained from vaginal swabs, cervicovaginal mucous (CVM), preputial washes and semen straws were investigated that were obtained from organized cattle farm of MLRI, Manasbal and unorganized sectors. Out of a total of 200 samples, 49 (47·57%) vaginal swabs, 1 (3·33%) preputial wash and 8 (25%) carried out CVM samples were positive for Cfv, whereas none of the semen straws were positive for Cfv. A total of eleven isolates of Cfv were recovered. PFGE (Pulse field gel electrophoresis) analysis revealed four different pulsotypes (I-IV) circulating in the screened farms. A common pulsotype circulating among farms could not be established. Insertion element (ISCfe1), a 233 bp amplicon of Cfv, was sequenced and the sequence was deposited in GenBank (accession no: MK475662).
Assuntos
Infecções por Campylobacter/veterinária , Campylobacter fetus/efeitos dos fármacos , Campylobacter/efeitos dos fármacos , Doenças dos Bovinos/microbiologia , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Campylobacter/classificação , Campylobacter/genética , Campylobacter/isolamento & purificação , Infecções por Campylobacter/microbiologia , Campylobacter fetus/classificação , Campylobacter fetus/genética , Campylobacter fetus/isolamento & purificação , Bovinos , Elementos de DNA Transponíveis , Farmacorresistência Bacteriana , Fazendas , Feminino , Genótipo , Índia , MasculinoRESUMO
BACKGROUND: Campylobacter fetus (C. fetus) can cause disease in both humans and animals. C. fetus has been divided into three subspecies: C. fetus subsp. fetus (Cff), C. fetus subsp. venerealis (Cfv) and C. fetus subsp. testudinum (Cft). Subspecies identification of mammal-associated C. fetus strains is crucial in the control of Bovine Genital Campylobacteriosis (BGC), a syndrome associated with Cfv. The prescribed methods for subspecies identification of the Cff and Cfv isolates are: tolerance to 1 % glycine and H2S production. RESULTS: In this study, we observed the deletion of a putative cysteine transporter in the Cfv strains, which are not able to produce H2S from L-cysteine. Phylogenetic reconstruction of the core genome single nucleotide polymorphisms (SNPs) within Cff and Cfv strains divided these strains into five different clades and showed that the Cfv clade and a Cff clade evolved from a single Cff ancestor. CONCLUSIONS: Multiple C. fetus clades were observed, which were not consistent with the biochemical differentiation of the strains. This suggests the need for a closer evaluation of the current C. fetus subspecies differentiation, considering that the phenotypic differentiation is still applied in BGC control programs.
Assuntos
Campylobacter fetus/classificação , Genoma Bacteriano , Sulfeto de Hidrogênio/metabolismo , Análise de Sequência de DNA/métodos , Proteínas de Bactérias/genética , Campylobacter fetus/genética , Campylobacter fetus/fisiologia , Cisteína/metabolismo , Evolução Molecular , Deleção de Genes , Tamanho do Genoma , Filogenia , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Campylobacter fetus spp. is a bacterium associated to reproductive losses in cattle worldwide. It is a venereal infectious disease known as bovine campilobacteriosis, with high impact mainly in countries with extensive production systems. Here, we show pathogenesis and diagnostic methods for Campylobacter fetus detection in cervico-vaginal mucus (CVM) samples from heifers experimentally infected and field cases from herds with low reproductive performance by campylobacteriosis infection. Bacterial culture, direct immunofluorescence test and qPCR were used as diagnostic methods to evaluate detection of C. fetus. In the experimental model 30 Aberdeen Angus and crossbred heifers and 4 Aberdeen Angus bulls for natural mating were assigned to 3 groups experimentally challenged with C. fetus subsp. fetus (Cff), C. fetus subsps venerealis (Cfv) and C. fetus subsp venerealis biovar intermedius (Cfvi), respectively, and a negative control group, all followed for 9 months. Also, field samples of CVM and aborted fetuses were recollected from seven beef cattle farms. Bacteriological culture had the higher C. fetus detection rate in CVM being the most appropriate, followed by qPCR (with commercial extraction DNA kit), direct immunofluorescence test and qPCR (with in-house extraction DNA method), in both, experimental model and field cases. From experimental model after natural mating, 62.5% and 25% heifers got pregnant from Cff and Cfvi groups, respectively, while from Cfv no pregnancy was detected. The strain more frequently detected was Cfvi, followed by Cff and Cfv. Colonization of Cff in female genital tract with high number of carriers and presence in aborted fetuses was evidenced, suggesting a high risk to bovine reproductive health. Bacteriemia was not detected after genital infection. Given the low detection rate of either test, we suggest the use of both, PCR based methods and bacterial culture could result in higher detection rate in farms with endemic campylobacteriosis.
Assuntos
Infecções por Campylobacter , Doenças dos Bovinos , Bovinos , Animais , Feminino , Masculino , Doenças dos Bovinos/epidemiologia , Infecções por Campylobacter/diagnóstico , Infecções por Campylobacter/veterinária , Vagina/microbiologia , Colo do Útero , DNARESUMO
Cattle farming is a major livestock activity with economic relevance in Rio Grande do Sul (RS), Brazil. However, this activity is still considered of intermediate to low technological level, and in this region, there are few epidemiologic reports of Campylobacter fetus subsp. venerealis (Cfv), the causative agent of bovine genital campylobacteriosis (BGC). Thus, we designed a cross-sectional study to assess the prevalence and Cfv-associated factors in cattle farms in RS, Brazil. In total, 99 farms were randomly selected to participate in the survey. Preputial mucus samples from selected bulls were collected twice (within a 15-day interval) and subjected to Cfv molecular detection. A farm was considered positive when at least one sample was positive for Cfv. Our findings indicate that the farm-level Cfv prevalence in RS is 67.67%. On average, the chance of a farm using natural service to be Cfv-positive increased approximately twice compared to farms that do not use natural service. We also determined that Cfv routine tests reduce the chance of a farm being positive by 92%. Therefore, both Cfv detection tests and the reduction of natural services decrease the chance of a farm being positive for Cfv. Finally, we conclude that Cfv is widely spread in Southern Brazil cattle farms and it is urgent the implementation of control measures to reduce Cfv prevalence in the target population.
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Infecções por Campylobacter , Doenças dos Bovinos , Bovinos , Animais , Masculino , Campylobacter fetus , Fazendas , Estudos Transversais , Brasil/epidemiologia , Prevalência , Infecções por Campylobacter/epidemiologia , Infecções por Campylobacter/veterinária , Infecções por Campylobacter/microbiologia , Doenças dos Bovinos/microbiologiaRESUMO
Bovine genital campylobacteriosis (BGC) is a leading cause of return to estrus in cows. The etiologic agent, Campylobacter fetus subsp. venerealis (Cfv) is transmitted by venereal route. Hence, the surrounding reproductive tract microenvironment could play a role in return to estrus in cows. The presence of Cfv in cervicovaginal mucus of Angus breed females provide three experimental groups, which were subject to bacteriome analyses: 10 Cfv-positive cows (CVP), 10 Cfv-negative cows (CVN), and 10 nonsexually active heifers (NSA). Cows with return to estrus showed higher bacterial richness than NSA. Beta diversity analysis showed a significant difference (P = 0.006) in bacterial composition among the three groups analyzed (CVP, CVN, and NSA). However, no significant difference was found when comparing the CVP versus CVN groups. Ureaplasma and Pseudomonas were the genera most frequently observed in NSA, being Ureaplasma the predictor genus to that group, whereas Alistipes, Bacteroides, Rikenellaceae_RC9_gut_group, UCG-005, and UCG-10 were both significantly more abundant and predictors genera in cows with return to estrus. Our results provide an overview of the cervicovaginal bacterial microbiota in cows harboring Cfv and improve the knowledge of the pathogenesis of BGC.
Assuntos
Infecções por Campylobacter , Campylobacter fetus , Bovinos , Animais , Feminino , Campylobacter fetus/genética , Infecções por Campylobacter/veterinária , Infecções por Campylobacter/microbiologia , MucoRESUMO
Contagious bovine genital campylobacteriosis (BGC), also known as bovine venereal campylobacteriosis, is a disease relevant to international trade listed by the World Organization for Animal Health (WOAH). It is caused by Campylobacter fetus subsp. venerealis (Cfv), one of three subspecies of Campylobacter fetus. Bulls are the reservoir but BGC may also be spread by artificial insemination (AI). BGC is characterized by severe reproductive losses such as infertility, early embryonic death and abortion with considerable economic losses. This significant economic impact has prompted several countries to adopt stringent eradication and surveillance measures to contain the disease. While there are commercial and autologous vaccines available, scientific evidence for the effectiveness of vaccination is still lacking. In Germany, BCG was already found to be endemic in the 1920s, shortly after the agent and the disease had been described for the first time. It can be assumed that BCG had already circulated uncontrolled for a long time in the predecessor states of Germany, influenced only by the political situation and trading networks of the time. After WW II, BCG was eradicated in the German Democratic Republic due to industrialized cattle production based on AI but it was still endemic at low levels in the Federal Republic of Germany with its diverse cattle production. There has been a steady decline in BGC incidence in re-unified Germany over the past 28 years. A single genetic Cfv lineage was identified which probably emerged in the 19th century and diversified over time. Interestingly, no recurrent cross-border introduction became evident. This review gives insight into the history of bovine genital campylobacteriosis considering the structural change in cattle farming in Germany and reflecting on the political background of the time.
RESUMO
Campylobacter fetus subsp. venerealis (Cfv) causes bovine genital campylobacteriosis (BGC), a World Organization for Animal Health (WOAH)-listed trade-relevant disease characterized by severe reproductive losses, such as infertility, early embryonic death and abortion in cattle. BGC has significant economic implications that have prompted several countries to adopt stringent eradication and surveillance measures to contain the disease. In Germany, there has been a low incidence of BGC cases over the past 28 years. This study aimed to illustrate the genomic diversity of German Cfv strains isolated from different federal states in Germany. This study analyzed 63 Cfv strains, collected between 1985 and 2015, by whole-genome sequencing and compared them with genome data of 91 international Cfv isolates. The phylogenetic analysis showed that the Cfv population is genetically conserved and has geographic clusters. In Germany, one phylogenetic lineage comprising all strains was identified. This German lineage was part of a subclade that probably emerged in the nineteenth century and diversified over time. The results of this study point to a non-recurrent cross-border introduction of Cfv in Germany. The BGC control interventions in Germany can be considered successful as no outbreaks were reported since 2015.
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Bovine Genital Campylobacteriosis (BGC) is a worldwide spread venereal disease of cattle caused by Campylobacter fetus subsp. venerealis (Cfv). Although several real-time PCR assays were developed for Cfv identification, most target mobile genetic elements, which may lead to false-positive diagnosis. In this study, a real-time PCR assay coupled with High-Resolution Melting analysis (HRM) was developed for the identification of Campylobacter fetus subspecies and application in BGC diagnosis. Two HRM assays targeting different single nucleotide polymorphisms were validated using 51 C. fetus strains, including 36 Cfv and 15 C. fetus subsp. fetus (Cff). The specificity was assessed in 50 preputial samples previously tested as negative for C. fetus and in 24 strains from other Campylobacter species. The analytical sensitivity was determined with ten-fold dilutions of Cfv genome copies and in preputial samples spiked with Cfv cells. Both HRM assays accurately identified the 51 C. fetus strains, showing 100% concordance with the previous identification. C. fetus subspecies identification by HRM showed concordant results with the glycine test in 98.0% of the isolates. No amplification was obtained in C. fetus negative preputial samples as well as in strains from other Campylobacter species. The assays were able to detect 102 genome copies of Cfv, while for preputial washing samples the limit of detection was 103 CFU/mL. These novel HRM assays represent a highly specific and sensitive tool for the identification of C. fetus subspecies and show potential for direct use in bull preputial samples for BGC diagnosis.
RESUMO
Campylobacter fetus is an important animal pathogen that causes infectious infertility, embryonic mortality and abortions in cattle and sheep flocks. There are two recognized subspecies related with reproductive disorders in livestock: Campylobacter fetus subsp. fetus (Cff) and Campylobacter fetus subsp. venerealis (Cfv). Rapid and reliable detection of this pathogenic species in bulls is of upmost importance for disease control in dairy and beef herds as they are asymptomatic carriers. The aim of the present work was to assess the performance a real-time PCR (qPCR) method for the diagnosis of Campylobacter fetus in samples from bulls, comparing it with culture and isolation methods. 520 preputial samples were both cultured in Skirrow's medium and analyzed by qPCR. The estimated sensitivity of qPCR was 90.9% (95% CI, 69.4%-100%), and the specificity was 99.4% (95% CI, 98.6% - 100%). The proportion of C. fetus positive individuals was 2.1% by isolation and 2.5% by qPCR. Isolates were identified by biochemical tests as Cfv (n = 9) and Cff (n = 2). Our findings support the use of qPCR for fast and accurate detection of C. fetus directly from field samples of preputial smegma of bulls. The qPCR method showed to be suitable for massive screenings because it can be performed in pooled samples without losing accuracy and sensitivity.
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The chemotaxis of C. fetus subsp. venerealis and C. fetus subsp. fetus was determined in the presence of bovine cervical mucus and bovine placental extract. Some reported substances and ion in those materials, such amino acids, ferrous iron, hormones, sugars and organic acids were also investigated. Bovine cervical mucus, bovine placenta extracts and some substances and ion of these materials namely L-fucose, L- aspartate, L-glutamate, L-serine, ferrous iron, fumarate, pyruvate and succinate were chemoattractants. The chemottraction was significantly larger in higher concentrations of the tested substances and ion and significant differences among tested strains were also observed. Meso-erythritol and hormones bovine placental lactogen, 17ß-estradiol, and progesterone did not elicit chemotactical response. In conclusion, this chemotactic behavior may guide the C. fetus navigation in the bovine host's genital tract and be an important cofactor of tissue tropism for this bacterium.
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Bovine genital campylobacteriosis (BGC) is a sexually transmitted disease that causes early reproductive failure in natural breeding cattle that are managed extensively. The aim of this study was to assess the BGC prevalence in Spain from 2011 to 2019 using data collected cross-sectionally from the diagnostic reports issued by the SALUVET veterinary diagnostic laboratory from a total of 5,182 breeding bulls from 1,950 herds managed under "dehesa" systems (large herds within fenced pastures and all-year breeding season) or mountain systems (smaller herds with seasonal breeding management and grazing in communal mountain pastures). Infection was detected by PCR in 7.7 and 12.2% of the bulls and herds tested, respectively. The "dehesa" herd management system (OR = 2.078, P = < 0.001, 95% CI = 1.55-1.77), bovine trichomonosis status of the herd (OR = 1.606, P = 0.004, 95% CI = 1.15-2.22), and bulls ≥3 years old (OR = 1.392, P = 0.04, 95% CI = 1.01-1.92) were identified as risk factors associated with Campylobacter fetus venerealis infection. We also studied the high-risk areas for circulation of the infection in extensive beef cattle herds in Spain, showing four significant clusters in "dehesa" areas in the south-western provinces of the country and a fifth cluster located in a mountain area in northern Spain. The results obtained in the present study indicate that BGC is endemic and widely distributed in Spanish beef herds. Specifically, "dehesa" herds are at greater risk for introduction of Cfv based on relatively high local prevalence of the infection and the use of specific management practices.
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Long transportation times remain a challenge to the satisfactory diagnosis of Campylobacter fetus subsp. venerealis (Cfv). Here we demonstrated that samples of frozen bovine preputial mucus maintained at -20 °C for 10 days can be used as an alternative source for molecular diagnosis of Cfv. This approach will improve the analysis of this bacterium.
Assuntos
Infecções por Campylobacter/diagnóstico , Infecções por Campylobacter/veterinária , Campylobacter/genética , Campylobacter/isolamento & purificação , Doenças dos Bovinos/diagnóstico , Animais , Bovinos , Congelamento , Técnicas de Diagnóstico Molecular/métodos , Manejo de EspécimesRESUMO
Subspecies of the species Campylobacter fetus are associated with specific host niches including mammals and reptiles. Campylobacter fetus subsp. fetus is a zoonotic pathogen infecting humans. Infections can vary from an acute intestinal illness to severe systemic infections, with sheep and cattle as major reservoirs. In contrast, Campylobacter fetus subsp. venerealis causes bovine genital campylobacteriosis, which leads to abortion in cattle and a high economic burden for the farmers. Therefore, high-quality molecular subtyping is indispensable for interventional epidemiology. We used whole-genome sequencing (WGS) data of 283 Campylobacter fetus strains from 18 countries and compared several methods for Campylobacter fetus subtyping, including WGS, multilocus sequence typing, PCR assays, and the presence of the insertion element ISCfe1. We identified a highly clonal clade (designated as clade 1) that harbors the insertion sequence ISCfe1. The presence of this insertion sequence is an essential diagnostic tool for the identification of the subspecies Campylobacter fetus subsp. venerealis, serving as a target for several PCR assays. However, we have found a high sequence variability for the ISCfe1 besides the presence of ISCfe1-paralogues in certain other genomes (n = 7) which may cause incorrect diagnostic results. Clade 1 seems to be the cattle-specific clade of this species. We propose that only this clade might be designated as Campylobacter fetus subsp. venerealis as it harbors the ISCfe1 marker sequence, which is a major target for molecular methods currently used for Campylobacter fetus subspecies identification. Fostering this proposal, we defined eleven stable nucleotide markers specific for this clade. Additionally, we developed a bioinformatics toolbox for the fast identification of this clade based on WGS data. In conclusion, our results demonstrate that WGS can be used for Campylobacter fetus subtyping overcoming limitations of current PCR and MLST protocols.
RESUMO
Phenotypic differences between Campylobacter fetus fetus and C. fetus venerealis subspecies allow the differential diagnosis of bovine genital campylobacteriosis. The hydrogen sulfide production, for example, is a trait exclusive to C. fetus fetus and C. fetus venerealis biovar intermedius. This gas that can be biochemically tested can be produced from L-cysteine (L-Cys). Herein, we report a novel multiplex-PCR to differentiate C. fetus based on the evaluation of a deletion of an ATP-binding cassette-type L-Cys transporter that could be involved in hydrogen sulfide production, as previously described. A wet lab approach combined with an in silico whole genome data analysis showed complete agreement between this L-Cys transporter-PCR and the hydrogen sulfide production biochemical test. This multiplex-PCR may complement the tests currently employed for the differential diagnosis of C. fetus.
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Bovine genital campylobacteriosis has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on the eligibility of bovine genital campylobacteriosis to be listed, Article 9 for the categorisation of bovine genital campylobacteriosis according to disease prevention and control rules as in Annex IV and Article 8 on the list of animal species related to bovine genital campylobacteriosis. The assessment has been performed following a methodology composed of information collection and compilation, expert judgement on each criterion at individual and, if no consensus was reached before, also at collective level. The output is composed of the categorical answer, and for the questions where no consensus was reached, the different supporting views are reported. Details on the methodology used for this assessment are explained in a separate opinion. According to the assessment performed, bovine genital campylobacteriosis can be considered eligible to be listed for Union intervention as laid down in Article 5(3) of the AHL. The disease would comply with the criteria as in sections 4 and 5 of Annex IV of the AHL, for the application of the disease prevention and control rules referred to in points (d) and (e) of Article 9(1). The assessment here performed on compliance with the criteria as in section 3 of Annex IV referred to in point (c) of Article 9(1) is inconclusive. The animal species to be listed for bovine genital campylobacteriosis according to Article 8(3) criteria is mainly cattle as susceptible and reservoir.
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Phenotypic differentiation between Campylobacter fetus (C. fetus) subspecies fetus and C. fetus subspecies venerealis is hampered by poor reliability and reproducibility of biochemical assays. AFLP (amplified fragment length polymorphism) and MLST (multilocus sequence typing) are the molecular standards for C. fetus subspecies identification, but these methods are laborious and expensive. Several PCR assays for C. fetus subspecies identification have been described, but a reliable comparison of these assays is lacking. The aim of this study was to evaluate the most practical and routinely implementable published PCR assays designed for C. fetus species and subspecies identification. The sensitivity and specificity of the assays were calculated by using an extensively characterized and diverse collection of C. fetus strains. AFLP and MLST identification were used as reference. Two PCR assays were able to identify C. fetus strains correctly at species level. The C. fetus species identification target, gene nahE, of one PCR assay was used to develop a real-time PCR assay with 100% sensitivity and 100% specificity, but the development of a subspecies venerealis specific real-time PCR (ISCfe1) failed due to sequence variation of the target insertion sequence and prevalence in other Campylobacter species. None of the published PCR assays was able to identify C. fetus strains correctly at subspecies level. Molecular analysis by AFLP or MLST is still recommended to identify C. fetus isolates at subspecies level.