Publications by authors named "Maria Isabel Romano"

17 Publications

  • Page 1 of 1

Effect of the deletion of lprG and p55 genes in the K10 strain of Mycobacterium avium subspecies paratuberculosis.

Res Vet Sci 2021 Sep 28;138:1-10. Epub 2021 May 28.

Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Hurlingham, Buenos Aires 1686, Argentina.

The lprG-p55 operon of Mycobacterium tuberculosis, M. bovis and M. avium strain D4ER has been identified as a virulence factor involved in the transport of toxic compounds. LprG is a lipoprotein that modulates the host immune response against mycobacteria, whereas P55 is an efflux pump that provides resistance to several drugs. In the present study we search for, and characterize, lprg and p55, putative virulence genes in Mycobacterium avium subsp. paratuberculosis (MAP) to generate a live-attenuated strain of MAP that may be useful in the future as live-attenuated vaccine. For this purpose, we generated and evaluated two mutants of MAP strain K10: one mutant lacking the lprG gene (ΔlprG) and the other lacking both genes lprG and p55 (ΔlprG-p55). None of the mutant strains showed altered susceptibility to first-line and second-line antituberculosis drugs or ethidium bromide, only the double mutant had two-fold increase in clarithromycin susceptibility compared with the wild-type strain. The deletion of lprG and of lprG-p55 reduced the replication of MAP in bovine macrophages; however, only the mutant in lprG-p55 grew faster in liquid media and showed reduced viability in macrophages and in a mouse model. Considering that the deletion of both genes lprG-p55, but not that of lprG alone, showed a reduced replication in vivo, we can speculate that p55 contributes to the survival of MAP in this animal model.
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http://dx.doi.org/10.1016/j.rvsc.2021.05.019DOI Listing
September 2021

Genetic diversity of sp. paratuberculosis by mycobacterial interspersed repetitive Unit-Variable number tandem repeat and multi-locus short-sequence repeat one-sentence summary: Genetic diversity of sp. paratuberculosis isolates.

Int J Mycobacteriol 2021 Jan-Mar;10(1):51-59

Institute of Agrobiotechnology and Molecular Biology (IABIMO)-CONICET, INTA De Los Reseros y Las Cabañas S/N, Hurlingham, Argentina.

Background: Paratuberculosis is an enteric disease caused by Mycobacterium avium sp. paratuberculosis (MAP) that affects mainly ruminant producing losses to the livestock industry. Many molecular epidemiological methods have been used to discriminate MAP isolates.

Method: The aim of this study was to describe the genetic diversity of the Argentinean MAP isolates using a combination of two molecular systems, the mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) ("automated and "non-automated") and the multi-locus short-sequence repeat (MLSSR) system.

Results: Thirty-two isolates were identified as MAP of C type by IS900 polymerase chain reaction (PCA) and IS1311 PCA-restriction enzyme analysis. The main patterns found by both MIRU-VNTR systems were INMV1 (54.5%), INMV2 (24.2%) and INMV11 (9.1%). The INMV5, INMV8 and INMV16 were represented with one isolate each (3.0%). Only 4 MIRU-VNTR loci were polymorphic.

Conclusion: Those isolates sharing the same INMV patterns were analyzed by MLSSR, being locus 2 the most polymorphic one showing isolates with 9, 10, 11, and more than 11 "G" repeats. Besides, the global discriminatory power among isolates could be increased using both techniques. Based on these results, a short version of the "automated" MIRU-VNTR could be used as a screening tool to group isolates genetically related and subsequently perform the SSR using locus 2 on those isolates sharing the same INMV pattern.
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http://dx.doi.org/10.4103/ijmy.ijmy_229_20DOI Listing
March 2021

Efficient method for targeted gene disruption by homologous recombination in Mycobacterium avium subspecie paratuberculosis.

Res Microbiol 2020 Jul - Sep;171(5-6):203-210. Epub 2020 Apr 10.

IABIMO Instituto de Agrobiotecnología y Biología Molecular, INTA-CONICET, Los Reseros y Nicolas Repetto 1686, Hurlingham, Buenos Aires, Argentina. Electronic address:

Targeted gene disruption by homologous recombination, has been widely used in mycobacterium species to understand the genetic basis of virulence and persistence in the host and to develop efficacious potential live vaccines. However, in slow growing pathogenic mycobacteria as Mycobacterium avium subsp paratuberculosis (MAP), these methods have been inefficient, in part due to the low frequency of legitimate homologous recombination. Another feature of mycobacteria is the low efficiency of transformation; therefore, some years ago, a phage-mediated transduction process was developed to introduce DNA into mycobacteria. This strategy is very efficient, due to the high rate of infection of the phage. This report describes a genetic method for the generation of targeted deletion mutations in MAP by allelic exchange using in vitro-generated specialized transducing mycobacteriophages, which does not require the critical packaging step and that could also be applied to other mycobacteria. We provide a detailed gene deletion methodology and demonstrate the use of this genetic system by deleting the mce4 operon of MAP. Finally, our results showed that the deletion of mce4 in MAP induces triacylglycerol accumulation; alter morphology and aggregation in liquid culture.
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http://dx.doi.org/10.1016/j.resmic.2020.04.001DOI Listing
March 2021

Protection efficacy of Argentinian isolates of Mycobacterium avium subsp. paratuberculosis with different genotypes and virulence in a murine model.

Res Vet Sci 2018 Dec 2;121:4-11. Epub 2018 Oct 2.

Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Biotecnología, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.

Paratuberculosis is a chronic disease caused by Mycobacterium avium subsp. paratuberculosis (Map). The disease causes economic losses and, therefore, it is imperative to follow proper control strategies, which should include an effective vaccine. Several strategies have assessed the virulence and immune response of Map strains that could be used as a vaccine. This study evaluates the degree of virulence, immune response, and protection of Argentinian strains of Map with different genotype in a murine model. Four local isolates (Cattle type) with different genotypes (analyzed by MIRU-VNTR and SSRs) were selected and evaluated in a virulence assay in BALB/c mice. This assay allowed us to differentiate virulent and low-virulence Map strains. The less virulent strains (1543/481 and A162) failed to induce a significant production of the proinflammatory cytokine IFNg, whereas the virulent strain 6611 established infection along with a proinflammatory immune response. On the other hand, the virulent strain 1347/498 was efficient in establishing a persistent infection, but failed to promote an important Th1 response compared with 6611 at the evaluated time. We selected the low-virulence strain 1543/498 as a live vaccine and the virulent strain 6611 as a live and inactivated vaccine in a protection assay in mice. Strain 1543/481 failed to protect the animals from challenge, whereas strain 6611, in its live and inactivated form, significantly reduced the CFUs count in the infected mice, although they had different immunological response profiles. The inactivated virulent strain 6611 is a potential vaccine candidate against paratuberculosis to be tested in cattle.
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http://dx.doi.org/10.1016/j.rvsc.2018.09.009DOI Listing
December 2018

Identification of the Apa protein secreted by Mycobacterium avium subsp. paratuberculosis as a novel fecal biomarker for Johne's disease in cattle.

Pathog Dis 2018 08 1;76(6). Epub 2018 Aug 1.

Laboratory of Biology of Recognition, Universidade Estadual do Norte Fluminense, Campos, 28013-602 Rio de Janeiro, Brazil.

Paratuberculosis (PTB) or Johne's disease is a chronic intestinal infection of ruminants, caused by Mycobacterium avium subsp. paratuberculosis. The shedding of mycobacteria in the feces starts at the initial stages and increases with disease progression, suggesting that antigens secreted by mycobacteria could be excreted in the feces. Previously, we demonstrated that the alanine and proline-rich antigen (Apa), a secretory antigen of Map, could be detected in the intestine of cows with PTB using a monoclonal antibody. In this study, we verified whether this protein can be found in consistently detectable levels in the feces of cattle with PTB. Feces were obtained from cows with Johne's disease confirmed by laboratory tests, cows with suspected PTB based on seropositivity and from PTB-free control cows. Samples were immunoprecipitated using anti-Apa monoclonal antibody and analyzed by immunoblot. The Apa was detected as a 60/70 kDa doublet band in all samples obtained from animals with laboratory-confirmed disease and in a substantial proportion of seropositive asymptomatic animals, but not in the control samples. Additionally, the antigen was detected in the feces of animals with Johne's disease by ELISA. This study strongly suggests that Apa is a potential fecal biomarker of Johne's disease that could serve for immunodiagnosis.
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http://dx.doi.org/10.1093/femspd/fty063DOI Listing
August 2018

Molecular typing of Argentinian Mycobacterium avium subsp. paratuberculosis isolates by multiple-locus variable number-tandem repeat analysis.

Braz J Microbiol 2015 Jun 1;46(2):557-64. Epub 2015 Jun 1.

Instituto Nacional de Tecnología Agropecuaria, Instituto de Biotecnología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria, Buenos Aires, Argentina, Instituto de Biotecnología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria, Buenos Aires, Argentina.

Multiple-locus variable number-tandem repeat analysis (MLVA) of Mycobacterium avium subspecies paratuberculosis (MAP) isolates may contribute to the knowledge of strain diversity in Argentina. Although the diversity of MAP has been previously investigated in Argentina using IS900-RFLP, a small number of isolates were employed, and a low discriminative power was reached. The aim of the present study was to test the genetic diversity among MAP isolates using an MLVA approach based on 8 repetitive loci. We studied 97 isolates from cattle, goat and sheep and could describe 7 different patterns: INMV1, INMV2, INMV11, INMV13, INMV16, INMV33 and one incomplete pattern. INMV1 and INMV2 were the most frequent patterns, grouping 76.3% of the isolates. We were also able to demonstrate the coexistence of genotypes in herds and co-infection at the organism level. This study shows that all the patterns described are common to those described in Europe, suggesting an epidemiological link between the continents.
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http://dx.doi.org/10.1590/S1517-838246220140283DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4507551PMC
June 2015

Description of a novel adhesin of Mycobacterium avium subsp. paratuberculosis.

Biomed Res Int 2014 22;2014:729618. Epub 2014 Jul 22.

Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria, 1686 Hurlingham, Buenos Aires, Argentina.

The binding and ingestion of Mycobacterium avium subsp. paratuberculosis (MAP) by host cells are fibronectin (FN) dependent. In several species of mycobacteria, a specific family of proteins allows the attachment and internalization of these bacteria by epithelial cells through interaction with FN. Thus, the identification of adhesion molecules is essential to understand the pathogenesis of MAP. The aim of this study was to identify and characterize FN binding cell wall proteins of MAP. We searched for conserved adhesins within a large panel of surface immunogenic proteins of MAP and investigated a possible interaction with FN. For this purpose, a cell wall protein fraction was obtained and resolved by 2D electrophoresis. The immunoreactive spots were identified by MALDI-TOF MS and a homology search was performed. We selected elongation factor Tu (EF-Tu) as candidate for further studies. We demonstrated the FN-binding capability of EF-Tu using a ligand blot assay and also confirmed the interaction with FN in a dose-dependent manner by ELISA. The dissociation constant of EF-Tu was determined by surface plasmon resonance and displayed values within the μM range. These data support the hypothesis that this protein could be involved in the interaction of MAP with epithelial cells through FN binding.
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http://dx.doi.org/10.1155/2014/729618DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4130151PMC
May 2015

Evaluation of cocktails with recombinant proteins of Mycobacterium bovis for a specific diagnosis of bovine tuberculosis.

Biomed Res Int 2014 8;2014:140829. Epub 2014 Jul 8.

Instituto de Biotecnología, INTA, Los Reseros y Nicolás Repetto, 1686 Hurlingham, Buenos Aires, Argentina.

The Delayed type hypersensitivity skin test (DTH) and interferon-gamma assay are used for the diagnosis of bovine tuberculosis (TBB). The specificity of these diagnoses, however, is compromised because both are based on the response against purified protein derivative of Mycobacterium bovis (PPD-B). In this study, we assessed the potential of two cocktails containing M. bovis recombinant proteins: cocktail 1 (C1): ESAT-6, CFP-10 and MPB83 and cocktail 2 (C2): ESAT-6, CFP-10, MPB83, HspX, TB10.3, and MPB70. C1, C2, and PPD-B showed similar response by DTH in M. bovis-sensitized guinea pigs. Importantly, C1 induced a lower response than PPD-B in M. avium-sensitized guinea pigs. In cattle, C1 displayed better performance than PPD-B and C2; indeed, C1 showed the least detection of animals either vaccinated or Map-infected. To optimize the composition of the cocktails, we obtained protein fractions from PPD-B and tested their immunogenicity in experimentally M. bovis-infected cattle. In one highly reactive fraction, seven proteins were identified. The inclusion of FixB in C1 enhanced the recognition of M. bovis-infected cattle without compromising specificity. Our data provide a promising basis for the future development of a cocktail for TBB detection without interference by the presence of sensitized or infected animals with other mycobacteria.
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http://dx.doi.org/10.1155/2014/140829DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4119628PMC
March 2015

Characterization of a Mycobacterium avium subsp. avium operon associated with virulence and drug detoxification.

Biomed Res Int 2014 20;2014:809585. Epub 2014 May 20.

Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Buenos Aires 1686, Argentina.

The lprG-p55 operon of Mycobacterium tuberculosis and Mycobacterium bovis is involved in the transport of toxic compounds. P55 is an efflux pump that provides resistance to several drugs, while LprG is a lipoprotein that modulates the host's immune response against mycobacteria. The knockout mutation of this operon severely reduces the replication of both mycobacterial species during infection in mice and increases susceptibility to toxic compounds. In order to gain insight into the function of LprG in the Mycobacterium avium complex, in this study, we assayed the effect of the deletion of lprG gene in the D4ER strain of Mycobacterium avium subsp. avium. The replacement of lprG gene with a hygromycin cassette caused a polar effect on the expression of p55. Also, a twofold decrease in ethidium bromide susceptibility was observed and the resistance to the antibiotics rifampicin, amikacin, linezolid, and rifabutin was impaired in the mutant strain. In addition, the mutation decreased the virulence of the bacteria in macrophages in vitro and in a mice model in vivo. These findings clearly indicate that functional LprG and P55 are necessary for the correct transport of toxic compounds and for the survival of MAA in vitro and in vivo.
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http://dx.doi.org/10.1155/2014/809585DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4055363PMC
February 2015

Search for Mycobacterium avium Subspecies paratuberculosis Antigens for the Diagnosis of Paratuberculosis.

Vet Med Int 2012 24;2012:860362. Epub 2012 Jun 24.

Instituto de Biotecnología, CICVyA, INTA, De Los Reseros y Dr. Nicolás Repetto S/N, Hurlingham, 1686 Buenos Aires, Argentina.

The aim of this study was to evaluate a wide panel of antigens of Mycobacterium avium subsp. paratuberculosis (MAP) to select candidates for the diagnosis of paratuberculosis (PTB). A total of 54 recombinant proteins were spotted onto nitrocellulose membranes and exposed to sera from animals with PTB (n = 25), healthy animals (n = 10), and animals experimentally infected with M. bovis (n = 8). This initial screening allowed us to select seven antigens: MAP 2513, MAP 1693, MAP 2020, MAP 0038, MAP 1272, MAP 0209c, and MAP 0210c, which reacted with sera from animals with PTB and showed little cross-reactivity with sera from healthy animals and animals experimentally infected with M. bovis. The second step was to evaluate the antigen cocktail of these seven antigens by ELISA. For this evaluation, we used sera from animals with PTB (n = 25), healthy animals (n = 26), and animals experimentally infected with M. bovis (n = 17). Using ELISA, the cocktail of the seven selected MAP antigens reacted with sera from 18 of the 25 animals with PTB and did not exhibit cross-reactivity with healthy animals and only low reactivity with animals with bovine tuberculosis. The combined application of these antigens could form part of a test which may help in the diagnosis of PTB.
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http://dx.doi.org/10.1155/2012/860362DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3389728PMC
August 2012

Accuracy assessment and screening of a dairy herd with paratuberculosis by three different ELISAs.

Vet Microbiol 2012 Apr 6;156(1-2):183-8. Epub 2011 Nov 6.

Instituto de Biotecnología, Centro de Investigaciones Veterinarias y Agronómicas (CICVyA), Instituto Nacional de Tecnología Agropecuaria (INTA), Hurlingham, Buenos Aires, Argentina.

Although the culture of Mycobacterium avium subsp. paratuberculosisis is the gold standard for the diagnosis of paratuberculosis, this bacterium is difficult to grow. In contrast, serological tests like ELISAs are inexpensive, rapid, and easy to perform. The aims of this study were to evaluate the accuracy of three different ELISAs: one with the commercial antigen PPA-3, another one with L5P (a recently described lipopentapeptide), and a third one with an in-house antigen whole cell lysates (WCL) of M. avium (MAA) strain D4ER (Study 1), and to compare them with other tests for paratuberculosis (PTB) diagnosis (Study 2). In Study 1, the sensitivities of the three ELISAs tested were 74.1%, 37% and 74.1%, respectively, whereas their specificities were 98.9%, 100% and 100%, respectively. In Study 2, we compared the three above-mentioned ELISAs with the intradermal reaction test using Avian PPD (PPDa) and fecal culture associated with Ziehl-Neelsen stain and PCR tests, in a dairy herd with 4.6% of cows with clinical signs of PTB. The results showed that fecal samples from 14 cows (16%) were culture-positive and that fecal samples from nine cows (10%) were PPDa-positive. Most of these animals (culture-positive and PPDa-positive) were detected as positive with any of the three ELISAs tested. Serological results showed that 31% of the animals were positive to ELISA-PPA-3, 17% to ELISA-L5P and 42.5% to ELISA-WCL. The combination of these three ELISAs identified 50.6% of the animals as positive in the infected herd. In particular, the results show that the locally developed ELISA seems to be useful for identifying many infected animals in a herd.
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http://dx.doi.org/10.1016/j.vetmic.2011.10.029DOI Listing
April 2012

An applied printing immunoassay with recombinant Nc-SAG1 for detection of antibodies to Neospora caninum in cattle.

J Vet Diagn Invest 2011 Sep 19;23(5):971-6. Epub 2011 Aug 19.

Biotechnology Institute, Veterinary and Agronomic Sciences Research Center (CICVyA), National Institute of Agricultural Technology (INTA), Castelar, Buenos Aires, Argentina.

Neospora caninum is a protozoan parasite that causes an important reproductive disease in cattle. Neospora caninum surface antigen 1 (Nc-SAG1) is an immunodominant candidate for the development of a diagnostic reagent for neosporosis. The current study describes the development and evaluation of an antigen print immunoassay (APIA) with recombinant Nc-SAG1 for the detection of specific antibodies to N. caninum in cattle. The concordance between APIA and a commercial enzyme-linked immunosorbent assay (ELISA) was evaluated with 232 serum samples from experimentally and naturally infected cattle. Sixty-one (26.7%) samples were positive for antibodies to N. caninum by ELISA and 58 (25.4%) by APIA. The new assay had a sensitivity of 85% and a specificity of 96%. These results, along with the potential of APIA to evolve into a multiple antigen detection format, suggest that this method would be a reliable diagnostic test for detection of antibodies to N. caninum in cattle.
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http://dx.doi.org/10.1177/1040638711416845DOI Listing
September 2011

Detection of Mycobacterium avium subsp. paratuberculosis by a Direct In Situ PCR Method.

Vet Med Int 2011 16;2011:267102. Epub 2011 Jun 16.

Instituto de Patobiología, CICVyA, INTA, De Los Reseros y Dr. Nicolás Repetto S/N, Hurlingham, 1686 Buenos Aires, Argentina.

In situ detection of Mycobacterium avium subsp. paratuberculosis is useful for diagnosis and research of paratuberculosis. The aim of this paper was to detect this agent in formalin-fixed, paraffin-embedded tissue samples by a direct in situ PCR. The technique was performed on ileum or ileocaecal lymph node samples from 8 naturally infected cattle and 1 healthy calf, by using p89 and p92 primers for amplification of IS900 sequence. Moderate positive signal was detected in all positive samples and not in negative control, but tissues resulted were affected in many cases due to the enzymatic treatment and the high temperature exposition. Although the technique was useful for Map detection, the signal was lower than immunohistochemistry probably because of the fixation process. In one case, signal was higher, which might be due to the detection of spheroplasts. Thus, the described method should be recommended when others resulted negative or for spheroplasts detection.
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http://dx.doi.org/10.4061/2011/267102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3134997PMC
November 2011

Spoligotype analysis of Mycobacterium bovis isolates from Northern México.

Can J Microbiol 2005 Nov;51(11):996-1000

Department of Immunology, Escuela Nacional de Ciencias Biologicas, IPN. Prolongacion Carpio y Plan de Ayala s/n, Colonia Santo Tomas, Mexico, DF 11340, Mexico.

Bovine tuberculosis is still rife in Latin America, producing huge economic losses. There are very few studies of the way this disease is spread through this geographical region, particularly in countries that border those that are almost free of Mycobacterium bovis. In this work, we have analyzed the spacer oligonucleotide typing (spoligotype) patterns of M. bovis isolates from cattle at Ciudad Juárez, a Mexican city close to El Paso, Texas. Fifty-eight M. bovis isolates collected from a herd in Northern Mexico were studied by spoligotyping. Nine spoligotype patterns were observed in total. Two were predominant (SB0121 and SB0140) and accounted for 50% and 14% of the isolates, respectively. Six patterns were found to be already described in an international M. bovis spoligotype database, while the other three (SB0985, SB0986, and SB0987) were novel. Interestingly, none of the isolates corresponded to any other Mexican pattern previously reported. This is the first spoligotype analysis of M. bovis strains from a border city between Mexico and the United States. The necessity for further studies to formulate a better identification of M. bovis strains within, and its dissemination between, the two countries is discussed.
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http://dx.doi.org/10.1139/w05-083DOI Listing
November 2005

Identification and characterization of genomic variations between Mycobacterium bovis and M. tuberculosis H37Rv.

J Clin Microbiol 2005 May;43(5):2481-4

Institute of Microbiology and Agricultural Zoology, CICVyA/INTA, Castelar, Argentina.

Genetic differences between Mycobacterium bovis and M. tuberculosis were identified. We found (i) a deletion of Rv3479 specific to M. bovis, (ii) that the rpfA gene is shortened to various extents in M. bovis, and (iii) an insertion in Rv0648 and a duplication of lppA common in M. tuberculosis complex isolates.
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http://dx.doi.org/10.1128/JCM.43.5.2481-2484.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1153726PMC
May 2005

Mutation in mce operons attenuates Mycobacterium tuberculosis virulence.

Microbes Infect 2005 Mar 1;7(3):325-34. Epub 2005 Feb 1.

Institute of Biotechnology, CICVyA-INTA, Los Reseros y Las Cabañas, 1712 Castelar, Argentina.

On the Mycobacterium tuberculosis genome there are four mce operons, all of which are similar in sequence and organization, and code for putatively exported proteins. To investigate whether Mce proteins are essential for virulence, we generated knock-out mutants in mce1, mce2 and mce3 operons of M. tuberculosis and evaluated their ability to multiply in a mammalian host. The allelic replacement was confirmed in each mutant strain by Southern blotting. RT-PCR experiments demonstrated the lack of in vitro expression of mutated genes in Deltamce1 and Deltamce2 mutants. On the other hand, no expression of mce3 was detected in either the wild-type or mutant strains. Similar doubling time and growth characteristics in in vitro culture were observed for mutants and parental strains. The intratracheal route was used to infect BALB/c mice with the Deltamce3, Deltamce2 and Deltamce1 mutants. Ten weeks after infection, all mice infected with the Deltamce mutants survived, while those infected with the wild-type strain died. This long survival correlated with very low counts of colony-forming units (CFU) in the lungs. Deltamce1-infected mice developed very few and small granulomas, while animals infected with Deltamce3 or Deltamce2 mutants showed delayed granuloma formation. Mice infected with Deltamce1 did not develop pneumonia, while animals infected with Deltamce3 and Deltamce2 mutants showed small pneumonic patches. In spleens, bacterial counts of mutant strains were less reduced than in lungs, compared with those of wild-type. In contrast, no such attenuation was observed when the intraperitoneal route was used for infection. Moreover, Deltamce1 mutants appear to be more virulent in lungs after intraperitoneal inoculation. In conclusion, mce operons seem to affect the virulence of M. tuberculosis in mice, depending on the route of infection. Hypotheses are discussed to explain this last issue. Thus, mutants in these genes seem to be good candidates for vaccine testing.
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http://dx.doi.org/10.1016/j.micinf.2004.11.007DOI Listing
March 2005

Tuberculosis in seals caused by a novel member of the Mycobacterium tuberculosis complex: Mycobacterium pinnipedii sp. nov.

Int J Syst Evol Microbiol 2003 Sep;53(Pt 5):1305-1314

Departamento de Micobacterias, DILACOT, Servicio Nacional de Sanidad y Calidad Agroalimentaria (SENASA), Avda A Fleming 1653, (1640) Martínez, Argentina.

A comparison of Mycobacterium tuberculosis complex isolates from seals (pinnipeds) in Australia, Argentina, Uruguay, Great Britain and New Zealand was undertaken to determine their relationships to each other and their taxonomic position within the complex. Isolates from 30 cases of tuberculosis in six species of pinniped and seven related isolates were compared to representative and standard strains of the M. tuberculosis complex. The seal isolates could be distinguished from other members of the M. tuberculosis complex, including the recently defined 'Mycobacterium canettii' and 'Mycobacterium caprae', on the basis of host preference and phenotypic and genetic tests. Pinnipeds appear to be the natural host for this 'seal bacillus', although the organism is also pathogenic in guinea pigs, rabbits, humans, Brazilian tapir (Tapirus terrestris) and, possibly, cattle. Infection caused by the seal bacillus is predominantly associated with granulomatous lesions in the peripheral lymph nodes, lungs, pleura, spleen and peritoneum. Cases of disseminated disease have been found. As with other members of the M. tuberculosis complex, aerosols are the most likely route of transmission. The name Mycobacterium pinnipedii sp. nov. is proposed for this novel member of the M. tuberculosis complex (the type strain is 6482(T)=ATCC BAA-688(T)=NCTC 13288(T)).
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http://dx.doi.org/10.1099/ijs.0.02401-0DOI Listing
September 2003
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