Mycobacterium Bovis In Cattle Research Articles

Highlighting on Mycobacterium Bovis in cattle, focusing on its antimicrobial resistance

Highlighting on Mycobacterium Bovis in cattle, focusing on its antimicrobial resistance

Serological, Morphological and Molecular Diagnosis of Mycobacterium bovis in Cattle at Sulaimani Province of Iraq

Background:Mycobacterium bovis (M. bovis) causes bovine tuberculosis (BTB), is an endemic disease in cattle and poses a high risk of spreading to humans.Objective:This study aimed to determine M. bovis in cattle and assess the similarities between cattle and humans through molecular methods and histopathological examinations.Methodology:Randomly, blood samples from 411 healthy appearance cows (1% of the target population) in five districts in Sulaimani province, Iraq, were collected from January to March 2022. Sera were obtained immediately and used for ELISA test to determine M. bovis. Additionally, the disease prevalence was confirmed by gross lesions at the slaughterhouse and histopathological examination of collected lymph nodes. Moreover, a PCR assay was used to detect M. bovis in suspected cow samples and previously diagnosed human samples. Gene sequencing and phylogenetic tree analysis were also done to determine the molecular differences between animal and human M. bovis.Results:Using an ELISA test, 46 (11.11%) of 414 samples were positive, while 368 (88.89%) were negative without significant differences between the districts (p>0.05). According to postmortem lesions at the slaughterhouse, only three cows were infected with TB, and typical gross lesions were calcified necrotic and multiple well-demarcated granulomas. The molecular test using two primers (CSB2 and oxyR gene) revealed that M. bovis was found in animal and human extra-pulmonary lymph nodes with no molecular change.Conclusion:Healthy cows harbored M. bovis, the causative agent of a contagious disease that spreads and causes a persistent health problem in humans.

Zoonotic tuberculosis in a high bovine tuberculosis burden area of Ethiopia.

Tuberculosis (TB) is a major cause of ill health and one of the leading causes of death worldwide, caused by species of the Mycobacterium tuberculosis complex (MTBC), with Mycobacterium tuberculosis being the dominant pathogen in humans and Mycobacterium bovis in cattle. Zoonotic transmission of TB (zTB) to humans is frequent particularly where TB prevalence is high in cattle. In this study, we explored the prevalence of zTB in central Ethiopia, an area highly affected by bovine TB (bTB) in cattle. A convenient sample of 385 patients with pulmonary tuberculosis (PTB, N = 287) and tuberculous lymphadenitis (TBLN, N = 98) were included in this cross-sectional study in central Ethiopia. Sputum and fine needle aspirate (FNA) samples were obtained from patients with PTB and TBLN, respectively, and cultures were performed using BACTEC™ MGIT™ 960. All culture positive samples were subjected to quantitative PCR (qPCR) assays, targeting IS1081, RD9 and RD4 genomic regions for detection of MTBC, M. tuberculosis and M. bovis, respectively. Two hundred and fifty-five out of 385 sampled patients were culture positive and all were isolates identified as MTBC by being positive for the IS1081 assay. Among them, 249 (97.6%) samples had also a positive RD9 result (intact RD9 locus) and were consequently classified as M. tuberculosis. The remaining six (2.4%) isolates were RD4 deficient and thereby classified as M. bovis. Five out of these six M. bovis strains originated from PTB patients whereas one was isolated from a TBLN patient. Occupational risk and the widespread consumption of raw animal products were identified as potential sources of M. bovis infection in humans, and the isolation of M. bovis from PTB patients suggests the possibility of human-to-human transmission, particularly in patients with no known contact history with animals. The detected proportion of culture positive cases of 2.4% being M. bovis from this region was higher zTB rate than previously reported for the general population of Ethiopia. Patients with M. bovis infection are more likely to get less efficient TB treatment because M. bovis is inherently resistant to pyrazinamide. MTBC species identification should be performed where M. bovis is common in cattle, especially in patients who have a history of recurrence or treatment failure.

Analysis of a multi-type resurgence of Mycobacterium bovis in cattle and badgers in Southwest France, 2007-2019

Although control measures to tackle bovine tuberculosis (bTB) in cattle have been successful in many parts of Europe, this disease has not been eradicated in areas where Mycobacterium bovis circulates in multi-host systems. Here we analyzed the resurgence of 11 M. bovis genotypes (defined based on spoligotyping and MIRU-VNTR) detected in 141 farms between 2007 and 2019, in an area of Southwestern France where wildlife infection was also detected from 2012 in 65 badgers. We used a spatially-explicit model to reconstruct the simultaneous diffusion of the 11 genotypes in cattle farms and badger populations. Effective reproduction number R was estimated to be 1.34 in 2007–2011 indicating a self-sustained M. bovis transmission by a maintenance community although within-species Rs were both < 1, indicating that neither cattle nor badger populations acted as separate reservoir hosts. From 2012, control measures were implemented, and we observed a decrease of R below 1. Spatial contrasts of the basic reproduction ratio suggested that local field conditions may favor (or penalize) local spread of bTB upon introduction into a new farm. Calculation of generation time distributions showed that the spread of M. bovis has been more rapid from cattle farms (0.5–0.7 year) than from badger groups (1.3–2.4 years). Although eradication of bTB appears possible in the study area (since R < 1), the model suggests it is a long-term prospect, because of the prolonged persistence of infection in badger groups (2.9–5.7 years). Supplementary tools and efforts to better control bTB infection in badgers (including vaccination for instance) appear necessary.

Bovine brucellosis and tuberculosis at a livestock-wildlife interface in Zimbabwe: A nexus for amplification of a zoonosis or a myth?

Bovine brucellosis and tuberculosis are important zoonoses affecting both livestock and wildlife. The study aimed to investigate seroprevalence of brucellosis and to isolate Brucella spp. and Mycobacterium bovis in cattle from livestock-wildlife interface areas. Three sites were selected from high, medium and low interface. The high interface was adjacent to the park and separated by a broken fence, while the medium and low interface were 15-20 and 50km from the perimeter fence, respectively. Cattle aged ≥2 years were randomly selected and bled for serology. Culture for brucellae and Mycobacterium species was attempted on lymph nodes collected at the slaughter floor. Sera were screened for Brucella antibodies using the Rose Bengal test and confirmed by the Complement fixation test. Data were analysed using a multivariable logistic regression model. Overall, seroprevalence was 11.7% (125/1068; 95% CI: 9.8-13.6%). High interface areas recorded significantly higher (p < 0.05) seroprevalence of 20.9% (85/406; 95% CI: 17.0-24.9%), compared to low 8.9% (31/350; 95% CI: 5.9-11.8%) and medium interface 2.9% (9/312; 95% CI: 1.0-4.8%). Brucella seropositivity was approximately three times higher (OR = 3.3, 95% CI: 2.1-5.3) for Malipati compared to Chiredzi. Similarly, the odds were twice (OR = 2.0, 95% CI: 1.2-3.5) in cows with history of abortion compared to those without. Brucella and Mycobacterium species were not isolated from all samples. The study highlighted the significance of high interface as a nexus for amplification of brucellosis in cattle. Thus, a brucellosis control programme that takes into consideration limiting livestock-wildlife interaction should be considered.

Bacteriological and Molecular studies on Mycobacterium Bovis in Cattle, with Special Reference to its Antimicrobial Resistance

In current study a total of 153 tuberculous lesion samples collected from cattle after PM examination (69 from El-Menufia, 47 from El-Sharkia and 37 from El-Qaliobia governorates) were subjected to bacteriological examination. Eighty-three samples showed the AF bacilli in direct smears stained by ZN stain at a percentage of 54.2% while by the culture method, M. bovis was isolated from 100 (65.4%) samples. Sixty-five isolates, confirmed to be M. bovis by conventional PCR targeting Mpb70, were tested for the sensitivity to anti-tuberculous drugs and 25 isolates showed resistance to at least one tested drug. The overall resistance to EMB was 3.1% and resistance to STR, INH and RIF were 20, 30.8 and 32.3% respectively. MDR was detected in 14 (21.5%) isolates. For DNA sequencing, PCR targeting rpoB gene, conferring rifampicin resistance, was performed on selected 6 isolates and identified three mutations designated as H526Y (4/6), S531L (1/6) and D516V (1/6) and the sequences were submitted to the NCBI GenBank with the accession numbers (OM448574, OM448575, OM448576, OM448577, OM448578 and OM448579). The obtained results are epidemiologically significant and augment the necessity of further investigation on ante-mortem identification of M. bovis infection in cattle to minimize public risk.

Spoligotyping, genotyping, and spatial distribution of Mycobacterium bovis in cattle in the state of Bahia, Brazil

ABSTRACT: Mycobacterium bovis is responsible for bovine and buffalo tuberculosis, an important zoonotic disease with global distribution. The knowledge of the distribution and the precise identification of this disease, including advanced diagnoses such as spoligotyping, allows choosing the best strategies to fight the disease’s progress. The present work aimed to investigate mycobacteria’s presence, genotype their strains, and evaluate tuberculosis cases’ spatial distribution from suggestive lesions in carcasses of bovine and buffalo inspected in slaughterhouses under an official inspection regime in the state of Bahia, Brazil. The study investigated 453,417 animals. Among these, 31 (0.007%) from 17 municipalities were suspected of tuberculosis. Among the culture medium growth, 95% of these were categorized as alcohol-acid resistant bacilli (BAAR). All isolates were subjected to spoligotyping and 95% were confirmed as M. bovis (SB0120, SB0121, SB0852, SB0828, SB0295, SB0881, SB1648, SB6119, SB0140, SB1055). The strain SB0120 was the most prevalent, and this profile has been described in cases of human tuberculosis by M. bovis, highlighting the zoonotic potential of this profile. This study also identified strains never reported in Bahia, highlighting a distinctive pattern from other parts of Brazil, besides mixed infections. Besides, to identify strains never before described in the state, highlighting a distinctive pattern in Brazil (SB6119 and SB0852, respectively). An unpublished profile was identified and inserted in the international database (Mbovis.org), named SB2715.

Evaluation of classical and rapid methods for isolation and identification of Mycobacterium bovis in cattle in Bulgaria

Bovine tuberculosis is still a serious problem with major economic impact in many countries. The aim of study was to evaluate the diagnostic capabilities of the classical and some modern, rapid methods for isolation and identification of Mycobacterium bovis. In the period 2015-2018 from 29 outbreaks in 10 different regions of Bulgaria, 1193 lymph nodes from slaughtered cattle were examined by pathoanatomical, bacteriological, PCR and immunochromatographic methods. Of the 283 bacterial isolates, 263 were identified as M. bovis - member of the M. tuberculosis complex.

Isolation and Histopathological Changes Associated with Non-Tuberculous Mycobacteria in Lymph Nodes Condemned at a Bovine Slaughterhouse.

Background: non-tuberculous mycobacteria (NTM) infect humans and animals and have a critical confounding effect on the diagnosis of bovine tuberculosis. The Official Mexican Standard (Norma Oficial Mexicana, NOM-ZOO-031-1995) for food safety regulates Mycobacterium bovis in cattle, but not the NTM species. The study’s objective was to isolate and identify the NTM present in condemned bovine lymph nodes in a slaughterhouse, characterize the histological lesions, and correlate bacteriological and microscopic findings with the antemortem tuberculin skin test. Methods: from 528 cattle, one or two pooled samples of lymph nodes from each animal were cultured for Mycobacteria spp. and processed for histopathology. Results: mycobacteria were isolated from 54/528 (10.2%) of the condemned lymph nodes; 25/54 (46.2%) of these isolates were NTM; 4 bacteriological cultures with fungal contamination were discarded. Granulomatous and pyogranulomatous inflammation were present in 6/21 (28.6%) and 7/21 (33.3%) of the NTM-positive lymph nodes, respectively. The species of NTM associated with granulomatous lymphadenitis were M. scrofulaceum, M. triviale, M. terrae, and M. szulgai, while those causing pyogranulomatous lesions were M. szulgai, M. kansasii, M. phlei, and M. scrofulaceum. Conclusions: the NTM infections can cause false-positive results in the tuberculin test because of cross immune reactivity and interference with the postmortem identification of M. bovis in cattle.

Assessment of candidate biomarkers to detect resistance to Mycobacterium bovis in Holstein-Friesian cattle

Bovine tuberculosis (bTB) caused by Mycobacterium bovis has a significant economic impact worldwide each year. Control of bTB is based on skin testing and removal of reactors. However, additional strategies are required to control this disorder. Natural disease resistance has been defined as the inherent capacity of an individual to resist disease when exposed to pathogens without previous exposure or immunization. However, little is known about natural disease resistance against Mycobacterium bovis in cattle. In this study, we aimed to identify candidate biomarkers to detect host resistance to M. bovis. We used a microbicidal assay to identify the resistance phenotype. A genomic microarray analysis was carried out on RNA from 2 resistant (R) and 2 susceptible (S) cows. Our results evidenced 69 differentially expressed genes. A subset of six genes that showed differential up (IL1RN), and down-regulation (VNN, GATM, ARHGEF11, NAAA and HSPA2) were selected for further analysis. To further validate the candidate biomarkers, we identified the R phenotype in 31 cattle (9 R and 22 S). Macrophage mRNA was isolated from this group of cattle. Expression of candidate biomarkers was evaluated by qPCR 2-ΔCt and ROC curves to determine their diagnostic potential. Candidates IL1RN and ARHGEF11 discriminates between R and S cattle. Furthermore, combination of candidates ARHGEF11: VNN: HSPA2 discriminate between R from S with AUC 0.7993 and agreement index of 0.853 (p ≤ 0.01). Our data suggest that candidate biomarkers may support the preliminary screening to identify natural resistance in herds against Mycobacterium bovis in Holstein-Friesian cattle.

Potential efficiency of conventional and advanced approaches used to detect Mycobacterium bovis in cattle

The present study was aimed to assess the prevalence and efficiency of techniques for the diagnosis of bovine tuberculosis (bTB) including enzyme-linked immunosorbent assay (ELISA), Gamma interferon assay (IFN-γ) and polymerase chain reaction (PCR) in comparison to skin tuberculin test and culture technique. A total of 2600 cross-breed dairy cattle in Menoufia and Daqahlia governorates were tested by the single intradermal tuberculin test where the disease prevalence was 1.8%. Serum and whole blood samples were collected from positive tuberculin reactors for ELISA and IFN-γ assay, respectively. After slaughtering of positive tuberculin reactors, the post-mortem examination was carried out and tissue samples were collected for the bacteriological examination and PCR. The percentage of visible lesions of tuberculin reactors was 78.7%, while non-visible lesions were 21.27%. Culture technique revealed that the percentage of bTB was 63.8%. The ELISA and IFN-γ assay using short-term culture filtrate (ST-CF) prepared antigen revealed higher sensitivity (72.3% and 82.9%) than the bovine purified protein derivative (PPD-B) antigen. Although prepared ST-CF antigen has great efficiency and eligibility for the diagnosis of bTB, PCR appeared to have a higher sensitivity (85.1%) than other diagnostic methods when dealing with post-mortem samples. Gamma interferon assay using ST-CF antigen is recommended for antemortem diagnosis of bTB in cattle.

Isolation and identification of Mycobacterium bovis in cattle slaughtered from an abattoir in Garanhuns, Pernambuco

Tuberculosis is a chronic infectious disease caused by the Mycobacterium tuberculosis complex (CMT), members including M. bovis. The sanitary inspection in slaughterhouses has a great importance on public health for the removal of contaminated meat with pathological lesions. Cattle slaughtered in the abattoir of Garanhuns were subjected to macroscopic, histological, bacteriological, and molecular analyses. Lung inspection revealed gross lesions suggestive of tuberculosis. The characterization of tuberculous granulomas was performed by histopathology and hematoxylin and eosin (HE) staining. The identification of acid-fast bacilli (AFB) was performed on smears with fresh material and histological staining using Ziehl-Neelsen stain. Bacteriological diagnosis was carried out using Stonebrink and Lowenstein-Jensen media, and polymerase chain reaction (PCR) was performed from the DNA extracted from colonies for the identification of Mycobacterium spp. We found that 1% (32/3,.180) of the collected lungs showed lesions suggestive of tuberculosis. Histopathological analysis revealed that 65.62% (21/32) samples had granulomatous pneumonia. AFB was detected in 46.88% (15/32) smears and 4.16% (1/24) histological sections, as analyzed by Ziehl-Neelsen staining. Moreover, 68.75% (22/32) samples showed bacterial growth and molecular identification 90% (18/20) of the samples were positive for M. bovis and 10% (2/20) for Mycobacterium sp. Thus, microbiological culture and PCR analyses revealed the high rate of bovine tuberculosis in this region, indicative of the need to disclose these results in the interest of public health. Consequently, we emphasize the need for an accurate macroscopic evaluation of lesions suggestive of bovine tuberculosis.

Assessment of antigenic supplementation of bovine purified protein derivative for diagnosis of subclinical infection with Mycobacterium bovis in cattle.

Bovine tuberculosis (bTB) is usually diagnosed invivo and exvivo on the basis of delayed hypersensitivity reactions with a complex pool of antigens named bovine tuberculin (PPDB). The IFN-γ release assay (IGRA) for bTB is a blood-based assay that improves detection of infected cattle at early stages that escape skin testing. Improvements to IFN-γ testing with specific proteins have been performed to increase sensitivity. DosR regulon-related antigens are well known mycobacterial proteins expressed during the non-replicative phases of infection, this has been useful to improve the diagnosis of subclinical forms of TB in suspected individuals. Transcripts of DosR genes mb2054c, mb2057c, and mb2660c have been identified by our group in lymph nodes of IFN-γ test negative cattle. This led us to hypothesize that DosR-related proteins may potentiate the IFN-γ response to PPDB in animals with a false negative IFN-γ test, making evident subclinical infection. Three hundred animals were evaluated by means of IGRA and post-mortem microbiological analysis of tissue samples to validate M.bovis infection. We found that 176 out of 300 animals showed an overall increased OD in complemented IGRA with two purified protein cocktails in comparison to PPDB alone, and were scrutinized for a subclinical infection; thirty percent when PPDB was supplemented with a cocktail of four DosR antigens, and 70% when PPDB was supplemented with a cocktail of six antigens (four DosR and two RD1 antigens). Forty five animals showed a substantial IFN-γ overproduction but remained negative, and 40 animals changed the result to a positive test. Only 18 out of 176 IFN-γ high producing animals were also positive to M.bovis isolation. Fifty seven animals with no visible lesions at slaughter and with a negative IGRA test result contained M.bovis DNA in tissue samples. In conclusion, Mb1762c, Mb2054c, Mb2057c, and Mb2660c have the potential to increase sensitivity of the IFN-γ invitro test for bTB diagnosis when supplemented to PPDB.

Detection of Mycobacterium tuberculosis and Mycobacterium bovis in Sahiwal cattle from an organized farm using ante-mortem techniques.

Aim:The aim of this study was to investigate the prevalence of bovine tuberculosis (TB) and detection of Mycobacterium bovis in cattle from an organized dairy farm.Materials and Methods:A total of 121 animals (93 females and 28 males) of 1 year and above were studied for the prevalence of bovine TB using single intradermal comparative cervical tuberculin (SICCT) test, bovine gamma-interferon (γ-IFN) enzyme immunoassay, and polymerase chain reactions (PCRs).Results:Out of total 121 animals, 17 (14.04%) animals were positive reactors to SICCT test while only one (0.82%) animal for γ-IFN assay. By PCR, Mycobacterium TB complex was detected in 19 (15.70%) animals out of which 4 (3.30%) animal were also positive for M. bovis.Conclusions:Diagnosis of bovine TB can be done in early stage in live animals with multiple approaches like skin test followed by a molecular technique like PCR which showed promising results.

Protection Induced by Simultaneous Subcutaneous and Endobronchial Vaccination with BCG/BCG and BCG/Adenovirus Expressing Antigen 85A against Mycobacterium bovis in Cattle.

The incidence of bovine tuberculosis (bTB) in the GB has been increasing since the 1980s. Immunisation, alongside current control measures, has been proposed as a sustainable measure to control bTB. Immunisation with Mycobacterium bovis bacillus Calmette-Guerin (BCG) has been shown to protect against bTB. Furthermore, much experimental data indicates that pulmonary local immunity is important for protection against respiratory infections including Mycobacterium tuberculosis and that pulmonary immunisation is highly effective. Here, we evaluated protection against M. bovis, the main causative agent of bTB, conferred by BCG delivered subcutaneously, endobronchially or by the new strategy of simultaneous immunisation by both routes. We also tested simultaneous subcutaneous immunisation with BCG and endobronchial delivery of a recombinant type 5 adenovirus expressing mycobacterial antigen 85A. There was significantly reduced visible pathology in animals receiving the simultaneous BCG/BCG or BCG/Ad85 treatment compared to naïve controls. Furthermore, there were significantly fewer advanced microscopic granulomata in animals receiving BCG/Ad85A compared to naive controls. Thus, combining local and systemic immunisation limits the development of pathology, which in turn could decrease bTB transmission.

Transgenic cattle produced by nuclear transfer of fetal fibroblasts carrying Ipr1 gene at a specific locus

This study aimed to assess the effects of the intracellular pathogen resistance 1 (Ipr1) transgene on preventing infection of Mycobacterium bovis in cattle. A specific expression vector for the Ipr1 gene was constructed and inserted in the genome between surfactant protein A and methionine adenosyltransferase I of bovine fetal fibroblasts. After SCNT, cleavage (86.9% vs. 87.4%, P > 0.05) and blastocyst developmental rates (34.6% vs. 33.5%, P > 0.05) were similar between transgenic and nontransgenic bovine fetal fibroblasts. Four surviving and one dead Ipr1-transgenic female cattle were produced by transfer of the SCNT blastocysts. Polymerase chain reaction and Southern blot analyses confirmed that the Ipr1 transgene of the cattle was located at the expected site. Inserting Ipr1 gene did not affect the expression of the surrounding genes. Main death modality of M bovis–infected peripheral blood mononuclear cells (PBMCs) derived from Ipr1-transgenic cattle was apoptosis, whereas that of PBMCs from control cattle was necrosis. In addition, the number of colony-forming units in PBMCs of Ipr1-transgenic cattle was significantly lower than that of the control cattle (P < 0.05). The finding that expression of Ipr1 transgene in PBMCs significantly increased anti–M bovis activity suggested breeding anti–M bovis cattle population by the transgenic SCNT technique could be a feasible strategy.

Farmers’ Beliefs and Risks of Bovine Tuberculosis in Cattle

This research examined farmers’ beliefs and possible association with Mycobacterium bovis in cattle. A survey of farmers in Midwest, U.S. with TB Positive herds, a Matching Control sample from TB positive areas, and farmers from areas that were TB Free was conducted. Data from 31 respondents yielded insights about the beliefs of farmers concerning how Bovine TB was transmitted and how the disease can be prevented. Comparison of the three groups suggests some important differences. Evidence suggests that farmers’ beliefs are important factors to consider with regard to control of the transmission of Bovine TB. While beliefs alone do not translate into behaviors, the findings suggest possibilities for preventive solutions that are specific to characteristics of a particular human ecosystem.

Virulence of Two Strains of Mycobacterium bovis in Cattle Following Aerosol Infection

Over the past two decades, highly virulent strains of Mycobacterium tuberculosis have emerged and spread rapidly in man, suggesting a selective advantage based on virulence. A similar scenario has not been described for Mycobacterium bovis infection in cattle (i.e. bovine tuberculosis). An epidemiological investigation of a recent outbreak of bovine tuberculosis in a USA dairy indicated that the causative strain of M. bovis (strain 10-7428) was particularly virulent, with rapid spread within the herd. In the present study, the virulence of this strain (10-7428) was directly compared in the target host with a well-characterized strain (95-1315) of relevance to the USA bovine tuberculosis eradication programme. Aerosol inoculation of 10(4) colony forming units of M. bovis 95-1315 (n=8) or 10-7428 (n=8) resulted in a similar distribution and severity of gross and microscopical lesions of tuberculosis as well as mycobacterial colonization, primarily affecting the lungs and lung-associated lymph nodes. Specific cell-mediated and antibody responses, including kinetics of the response, as well as antigen recognition profiles, were also comparable between the two treatment groups. Present findings demonstrate that M. bovis strains 95-1315 and 10-7428 have similar virulence when administered to cattle via aerosol inoculation. Other factors such as livestock management practices likely affected the severity of the outbreak in the dairy.

Relevance of bovine tuberculosis research to the understanding of human disease: Historical perspectives, approaches, and immunologic mechanisms

Pioneer studies on infectious disease and immunology by Jenner, Pasteur, Koch, Von Behring, Nocard, Roux, and Ehrlich forged a path for the dual-purpose with dual benefit approach, demonstrating a profound relevance of veterinary studies for biomedical applications. Tuberculosis (TB), primarily due to Mycobacterium tuberculosis in humans and Mycobacterium bovis in cattle, is an exemplary model for the demonstration of this concept. Early studies with cattle were instrumental in the development of the use of Koch's tuberculin as an in vivo measure of cell-mediated immunity for diagnostic purposes. Calmette and Guerin demonstrated the efficacy of an attenuated M. bovis strain (BCG) in cattle prior to use of this vaccine in humans. The interferon-γ release assay, now widely used for TB diagnosis in humans, was developed circa 1990 for use in the Australian bovine TB eradication program. More recently, M. bovis infection and vaccine efficacy studies with cattle have demonstrated a correlation of vaccine-elicited T cell central memory (TCM) responses to vaccine efficacy, correlation of specific antibody to mycobacterial burden and lesion severity, and detection of antigen-specific IL-17 responses to vaccination and infection. Additionally, positive prognostic indicators of bovine TB vaccine efficacy (i.e., responses measured after infection) include: reduced antigen-specific IFN-γ, iNOS, IL-4, and MIP1-α responses; reduced antigen-specific expansion of CD4+ T cells; and a diminished activation profile on T cells within antigen stimulated cultures. Delayed type hypersensitivity and IFN-γ responses correlate with infection but do not necessarily correlate with lesion severity whereas antibody responses generally correlate with lesion severity. Recently, serologic tests have emerged for the detection of tuberculous animals, particularly elephants, captive cervids, and camelids. B cell aggregates are consistently detected within tuberculous lesions of humans, cattle, mice and various other species, suggesting a role for B cells in the immunopathogenesis of TB. Comparative immunology studies including partnerships of researchers with veterinary and medical perspectives will continue to provide mutual benefit to TB research in both man and animals.

Association between spoligotype-VNTR types and virulence of Mycobacterium bovis in cattle

Mycobacterium bovis is the causative agent of bovine tuberculosis, a disease that affects approximately 5% of Argentine cattle. The aim of this research was to study if it is possible to infer the degree of virulence of different M. bovis genotypes based on scorified observations of tuberculosis lesions in cattle. In this study, we performed association analyses between several parameters with tuberculosis lesions: M. bovis genotype, degree of progression of tuberculosis, and animal age. For this purpose, the genotype was determined by spoligotyping and the degree of bovine tuberculosis gross lesion was quantified with a score based on clinical observations (number, size, and location of granulomas along with histopathologic features). This study was performed with naturally infected cattle of slaughterhouses from three provinces in Argentina. A total of 265 M. bovis isolates were obtained from 378 pathological lesion samples and 192 spoligotyping and VNTR (based on ETR sequences) typing patterns were obtained. SB0140 was the most predominant spoligotype, followed by SB0145. The spoligotype with the highest lesion score was SB0273 (median score of 27 ± 4.46), followed by SB0520 (18 ± 5.8). Furthermore, the most common spoligotype, SB0140, had a median score of 11 ± 0.74. Finally, the spoligotype with the lowest score was SB0145 (8 ± 1.0). ETR typing of SB0140, SB0145, SB0273, and SB0520 did not subdivide the lesion scores in those spoligotypes. In conclusion, SB0273 and SB0520 were the spoligotypes with the strongest association with hypervirulence and both spoligotypes were only found in Río Cuarto at the south of Córdoba province. Interestingly, there is no other report of any of these spoligotyes in Latin America.