88 research outputs found
Original Mycobacterial Sin, a consequence of highly homologous antigens?
The role of antigens shared between Mycobacteria in in-vivo cross-reactive immune responses in host animals,
have been reported to be responsible for reduced BCG vaccination efficacy as well reduced specificity of routine
immunological diagnostic tests. This presents with significant disease control challenges in humans and animals.
The present review highlights the results of previous studies on the effect of pre-sensitization to environmental
mycobacteria on either pathogenic mycobacteria and/or M. bovis BCG, in experimental animals. It also takes an
in-depth view into assessing the genetic similarities and relationships between atypical mycobacteria and
Mycobacterium tuberculosis complex (MTBC) and how they might explain the immunological imprint of
environmental mycobacteria in directing the hostsā immune response upon subsequent exposure to other classes
of mycobacteria. The outcome of this review suggests that genetic closeness between particular atypical
mycobacteria and MTBC usually indicate a higher level of homology for certain shared protective antigens. This
ultimately results in a higher level of cross reactive immune responses as compared with other atypical
mycobacteria that are further away genetically. This would explain the different effects of environmental
mycobacteria on MTBC that have been reported in the different studies. In other words the direction of the host
immune system in response to exposure to MTBC would depend on the type of environmental mycobacteria that
was encountered in the initial exposure. We also explain these mycobacterial interactions in the context of the
phenomenon of āOriginal Mycobacterial Sinā. The effects of these inevitable mycobacterial interactions on field
diagnosis and control by vaccination and how to circumvent them are discussed.http://www.elsevier.com/locate/vetmicam2017Veterinary Tropical Disease
A longitudinal study of factors influencing the result of a mycobacterium avium ssp. paratuberculosis antibody ELISA in milk of dairy cows
The influence of milk yield and milk composition
on the diagnosis of Mycobacterium avium ssp. paratuberculosis
(MAP) by milk ELISA in the context of
the total IgG secretion patterns in milk throughout
lactation and serum concentrations were investigated.
A 2-yr trial was performed in which 1,410 dairy cows
were sampled monthly and MAP milk ELISA status
and milk yield and composition were determined. Data
were analyzed by mixed model analysis. Milk yield
was found to significantly influence ELISA results
expressed as sample-to-positive (S/P) ratios. For each
5-kg increase in milk, the S/P ratio has to be multiplied
by 0.89; therefore, high milk yield can change the MAP
milk ELISA outcome of a cow in early infection from
positive to negative. Parity influenced ELISA outcome
significantly, indicating that cows with a parity >1 are
more likely to be identified by milk testing. Also, herd
was an important predictor, showing that herd prevalence
influences the milk ELISA strongly. Other factors
influencing the S/P ratios were protein concentration,
somatic cell count, and days in milk. The IgG concentration
and mass excreted per day were determined
longitudinally in a subset of 41 cows of which samples
and data of a complete lactation were available. Again,
the IgG concentration in milk was mainly influenced by milk yield. The total IgG mass secreted per day in milk
was found to be relatively constant, with a mean of
8.70 Ā± 5.38 g despite an increasing IgG concentration
in serum at the same time. The variation of IgG concentration
in milk can be mainly attributed to dilution
through changes in milk yield. This supports the assumption
that concentrations of MAP-specific antibodies
are influenced by changes in milk yield similarly. In
conclusion, we confirmed that antibody concentrations, and therefore MAP ELISA outcome, were influenced by
milk yield, herd, and parity. To enhance performance,
milk ELISA tests should either be performed in early or
late lactation, when milk yield is low. From a management
perspective, sampling should be done during early
lactation before cows are bred again. Based on the slow
progressive infection dynamics, only first-parity cows
should be preferentially tested at the end of their first
lactation to avoid false-negative results.The study was partly funded by Stichting Mesdagzuivelfonds
(NLTO, Leeuwarden, The Netherlands).http://www.journalofdairyscience.orgam201
Lepra bubalorum, a potential reservoir of Mycobacterium leprae
In 1926, a mycobacterial skin disease was observed in water buffaloes by researchers in
Indonesia. The disease was designated as skin tuberculosis, though it was hypothesized
that it might be a form of leprosy or a leprosy-like disease. In a follow-up study (Ph.D.
thesis Lobel, 1934, Utrecht University, Netherlands) a similar nodular skin disease was
described in Indonesian water buffaloes and named ālepra bubalorumā or ānodular
leprosy.ā Two decades later Kraneveld and Roza (1954) reported that, so far, the
diagnosis lepra bubalorum had been made in 146 cases in Indonesia. After a final
series of research reports by Indonesian veterinarians in 1961, no subsequent cases
were published. Based on information from these reports, it can be concluded that,
even though evidence of nerve involvement in buffaloes was not reported, similarities
exist between lepra bubalorum and Hansenās disease (leprosy), i.e., nodular skin lesions
with a chronic course and microscopically granulomatous reactions with AFB in globi
in vacuoles. This raises the question as to whether these historical cases might indeed
have been caused by Mycobacterium leprae, Mycobacterium lepromatosis or another
representative of the M. leprae complex. The future use of state-of-the-art molecular
techniques may answer this question and may also help to answer the question whether
water buffaloes should be considered as a potential natural reservoir of the causative
pathogen of Hansenās disease.http://www.frontiersin.org/Microbiologyam2022Veterinary Tropical Disease
Farm-level risk factors associated with bovine tuberculosis in the dairy sector in Eritrea
The aim of our study was to determine the association of selected potential risk factors
with the presence of bovine tuberculosis (BTB) in dairy herds in Eritrea. A caseācontrol
study was conducted in the three major milk-producing regions of the country by stratified
random sampling of 61 case and 65 control herds combined with completion of a
standardized pretested questionnaire pertaining 36 relevant risk factors (variables). The
variables were divided into two clusters, based on potential association with either āintroductionā
or āestablishmentā of BTB on the farms to elucidate association with incident
or prevalent cases separately. Subsequent to univariable analysis of the 36 risk
factors at herd level, 14 of these were offered to multivariable logistic regression models.
Farms with higher numbers of cows, and those with concrete floors, were 3.6, and
7.5 times more at risk for presence of BTB, respectively, compared with their references.
These findings will be useful as entry points for future informed decision-making
towards BTB control and eradication programme in the country.Netherlands Organization for International
Cooperation in Higher Education.http://wileyonlinelibrary.com/journal/tbedam2018Veterinary Tropical Disease
Reservoirs and transmission routes of leprosy : a systematic review
Leprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae) and
the more recently discovered Mycobacterium lepromatosis (M. lepromatosis). The two leprosy
bacilli cause similar pathologic conditions. They primarily target the skin and the peripheral
nervous system. Currently it is considered a Neglected Tropical Disease, being
endemic in specific locations within countries of the Americas, Asia, and Africa, while in
Europe it is only rarely reported. The reason for a spatial inequality in the prevalence of leprosy
in so-called endemic pockets within a country is still largely unexplained. A systematic
review was conducted targeting leprosy transmission research data, using PubMed and
Scopus as sources. Publications between January 1, 1945 and July 1, 2019 were included.
The transmission pathways of M. leprae are not fully understood. Solid evidence exists of an
increased risk for individuals living in close contact with leprosy patients, most likely through
infectious aerosols, created by coughing and sneezing, but possibly also through direct contact.
However, this systematic review underscores that human-to-human transmission is
not the only way leprosy can be acquired. The transmission of this disease is probably much
more complicated than was thought before. In the Americas, the nine-banded armadillo
(Dasypus novemcinctus) has been established as another natural host and reservoir of M.
leprae. Anthroponotic and zoonotic transmission have both been proposed as modes of
contracting the disease, based on data showing identical M. leprae strains shared between
humans and armadillos. More recently, in red squirrels (Sciurus vulgaris) with leprosy-like lesions in the British Isles M. leprae and M. lepromatosis DNA was detected. This finding
was unexpected, because leprosy is considered a disease of humans (with the exception of
the armadillo), and because it was thought that leprosy (and M. leprae) had disappeared
from the United Kingdom. Furthermore, animals can be affected by other leprosy-like diseases,
caused by pathogens phylogenetically closely related to M. leprae. These mycobacteria
have been proposed to be grouped as a M. leprae-complex. We argue that insights
from the transmission and reservoirs of members of the M. leprae-complex might be relevant
for leprosy research. A better understanding of possible animal or environmental reservoirs
is needed, because transmission from such reservoirs may partly explain the steady global incidence of leprosy despite effective and widespread multidrug therapy. A reduction
in transmission cannot be expected to be accomplished by actions or interventions from the
human healthcare domain alone, as the mechanisms involved are complex. Therefore, to
increase our understanding of the intricate picture of leprosy transmission, we propose a
One Health transdisciplinary research approach.S1 PRISMA Checklist.S1 Text.https://journals.plos.org/plosntdsam2021Veterinary Tropical Disease
Prevalence and distribution of non-tuberculous mycobacteria (NTM) in cattle, African buffaloes (Syncerus caffer) and their environments in South Africa
It has been hypothesized that a variety of non-tuberculous mycobacteria (NTM) species to which livestock and wildlife species are naturally exposed induce broadly cross-reactive anti-mycobacterial immune responses which interfere with current standard diagnostic assays. Non-tuberculous mycobacteria have also been implicated in Mycobacterium bovis-specific immune responsiveness, hence potentially the development of tuberculosis. Cattle and African buffaloes are both maintenance hosts of bovine tuberculosis (BTB) in South Africa, yet the effective diagnosis and control in these species may be hampered by adverse effects of NTM. As part of an investigation of the role of NTM in the immune responsiveness of cattle and African buffaloes to NTM, we conducted a countrywide survey to establish the prevalent NTM species and their distribution in the natural environments of these animals. A total of 1123 samples (water, soil, nasal and pharyngeal swabs) were collected for mycobacterium isolation. In addition, NTM isolated from tissue samples between 1991 and 2011 were included in the analysis. Mycobacteria were isolated from 56% of the samples from the countrywide survey. A total of 420 NTM isolates from soil, water, animal tissues and animal-derived swab samples were genotyped with the following results: 302 belonged to 40 known NTM species, 79 were found to be closely related to 23 known NTM species, and 38 isolates were found to be potentially novel species that are not currently listed in the RIDOM and NCBI BLAST databases. The four NTM species or closely related groups most frequently isolated in this survey included Mycobacterium terrae (11.2% of isolates), a group of mycobacteria closely related to Mycobacterium moriokaense (referred to as M. moriokaense-like) (8.1% of isolates), Mycobacterium nonchromogenicum (7.4% of isolates) and Mycobacterium vaccae/M. vanbaalenii (5.2% of isolates). The phylogenetic analysis of the M. moriokaense-like isolates, based on the 16S rRNA sequences, revealed at least eight clusters, possibly associated with eight different NTM species. Our findings provide account of NTM species diversity and associated prevalences in cattle and African buffaloes and their environments in South Africa. The identification of the most prevalent NTM species in this study will allow for a targeted investigation of their effects on host immune responses.WOTRO Integrated Programme 2008http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1865-1682hb2014ab201
Subpopulations of bovine WC1+ Ī³Ī“ T cells rather than CD4+CD25highFoxp3+ T cells act as immune regulatory cells ex vivo
Regulatory T cells (Treg) are regarded essential components for maintenance of immune homeostasis. Especially CD4+CD25high T cells are considered to be important regulators of immune reactivity. In humans and rodents these natural Treg are characterized by their anergic nature, defined as a non-proliferative state, suppressive function and expression of Foxp3. In this study the potential functional role of flowcytometry-sorted bovine white blood cell populations, including CD4+CD25high T cells and Ī³Ī“ T cell subpopulations, as distinct ex vivo regulatory cells was assessed in co-culture suppression assays. Our findings revealed that despite the existence of a distinct bovine CD4+CD25high T cell population, which showed Foxp3 transcription/expression, natural regulatory activity did not reside in this cell population. In bovine co-culture suppression assays these cells were neither anergic nor suppressive. Subsequently, the following cell populations were tested functionally for regulatory activity: CD4+CD25low T cells, WC1+, WC1.1+ and WC1.2+āĪ³Ī“ T cells, NK cells, CD8+ T cells and CD14+ monocytes. Only the WC1.1+ and WC1.2+āĪ³Ī“ T cells and CD14+ monocytes proved to act as regulatory cells in cattle, which was supported by the fact that these regulatory cells showed IL-10 transcription/expression. In conclusion, our data provide first evidence that cattle CD4+CD25highFoxp3+ and CD4+CD25low T cells do not function as Treg ex vivo. The bovine Treg function appears to reside in the Ī³Ī“ T cell population, more precisely in the WC1.1+ and the WC1.2+ subpopulation, major populations present in blood of cattle in contrast to non-ruminant species
Mycobacterium malmesburyense sp. nov : a novel non-tuberculous Mycobacterium species revealed by multiple gene sequence characterization
Non-tuberculous mycobacteria (NTM) are ubiquitous in the environment and an increasing
number of NTM species have been isolated and characterized from both humans and animals,
highlighting the zoonotic potential of these bacteria. Host exposure to NTM may impact on
cross-reactive immune responsiveness which may affect diagnosis of bovine tuberculosis and
may also play a role in the variability of the efficacy of Mycobacterium bovis BCG
vaccination against tuberculosis. In this study we characterized 10 NTM isolates originating
from water, soil, nasal swabs of cattle and African buffalo as well as bovine tissue samples.
These isolates were previously identified during an NTM survey and were all found, using
16S rDNA sequence analysis to be closely-related to Mycobacterium moriokaense. A
polyphasic approach that includes phenotypic characterization, antibiotic susceptibility
profiling, mycolic acid profiling and phylogenetic analysis of four gene loci, viz 16S rDNA,
hsp65, sodA, and rpoB was employed to characterize these isolates. Sequence data analysis of
the four gene loci revealed that these isolates belong to a unique Mycobacterium species. This
evidence was further supported by several differences in phenotypic characteristics between
the isolates and the closely related species. We proposed the name, Mycobacterium
malmesburyense sp. nov. for this new species. The type strain is WCM 7299T (ATCCĀ® BAA-
2759TM =CIP 110822T). The Genbank accession numbers for the partial gene sequences [16S
rDNA , hsp65, rpoB and sodA] for the type strain are as follows: 16S rRNA= KJ 873241;
hsp65=KJ 873243; rpoB= KJ 873245; sodA= KJ 873247.WOTRO Science for global development; grant number W01.65.321.00.http://ijs.sgmjournals.orghb2017Veterinary Tropical Disease
Prevalence and demographic risk factors of Mycobacterium tuberculosis infections in captive Asian elephants (Elephas maximus) based on serological assays
To address putative TB statuses of elephants and to identify and quantify potential
demographic risk factors for TB, three ELISAs specific for different mycobacterial
antigens (ESAT6, CFP10, MPB83) and the TB Stat-Pak assay were used as surrogate
serological markers for TB infection in elephants. In view of the low number of animals
of which the infected status could be confirmed (4 out of 708) Latent Class Analyses of
TB serology test outcomes was used to predict the putative TB status of each of 708
elephants as positive (17.3%), inconclusive (48.7%), or negative (34%) when assessed
on a population basis. Correlation between test performance of the individual assays
was high between the ELISAs, but low with that of the TB Stat-Pak assay. Risk factors,
assessed based on cut off values for each of the ELISAs determined by ROC analysis,
included sex, BCS, age, working time, feed type, management system, camp size and
region. Old age elephants were more likely to show a positive TB serology test outcome,
than younger ones. Elephants working 7 h per day and the ones in good condition BCS
(7ā11) were less likely to be positive in TB serology testing. In addition, fewer animals in
the large camp size (31ā50 elephants) were found to be positive in ELISA tests, compared
to elephants in the other camp sizes. In this study, the North region had the lowest
percentages of elephants with positive TB test outcome, the West region and to a lesser
extend the other regions showed clearly higher percentages of positive animals. Even
though assays used in the present study have not been validated yet, results obtained
showed promise as diagnostic or screening tests. For the diagnosis of animals suspected
to be infected, the ELISA tests, once further optimized for the individual antigens, can be
used in parallel. For screening of complete camps for presence or absence of infection,
a single optimized ELISA test can be utilized.Faculty of Veterinary Medicine, Chiangmai Universityhttps://www.frontiersin.org/journals/veterinary-science#am2022Veterinary Tropical Disease
The interplay between salmonella and intestinal innate immune cells in chickens
Salmonellosis is a common infection in poultry, which results in huge economic losses
in the poultry industry. At the same time, Salmonella infections are a threat to public health, since
contaminated poultry products can lead to zoonotic infections. Antibiotics as feed additives have
proven to be an effective prophylactic option to control Salmonella infections, but due to resistance
issues in humans and animals, the use of antimicrobials in food animals has been banned in Europe.
Hence, there is an urgent need to look for alternative strategies that can protect poultry against
Salmonella infections. One such alternative could be to strengthen the innate immune system in
young chickens in order to prevent early life infections. This can be achieved by administration of
immune modulating molecules that target innate immune cells, for example via feed, or by in-ovo
applications. We aimed to review the innate immune system in the chicken intestine; the main site of
Salmonella entrance, and its responsiveness to Salmonella infection. Identifying the most important
players in the innate immune response in the intestine is a first step in designing targeted approaches
for immune modulation.The Punjab Educational Endowment Fund, Punjab, Pakistan.https://www.mdpi.com/journal/pathogensam2022Veterinary Tropical Disease
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