Publications by authors named "Alejandro Abdala"

7 Publications

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BLV: lessons on vaccine development.

Retrovirology 2019 10 7;16(1):26. Epub 2019 Oct 7.

Molecular and Cellular Epigenetics (GIGA) and Molecular Biology (TERRA), University of Liège (ULiège), 4000, Liege, Belgium.

Vaccination against retroviruses is a challenge because of their ability to stably integrate into the host genome, undergo long-term latency in a proportion of infected cells and thereby escape immune response. Since clearance of the virus is almost impossible once infection is established, the primary goal is to achieve sterilizing immunity. Besides efficacy, safety is the major issue since vaccination has been associated with increased infection or reversion to pathogenicity. In this review, we discuss the different issues that we faced during the development of an efficient vaccine against bovine leukemia virus (BLV). We summarize the historical failures of inactivated vaccines, the efficacy and safety of a live-attenuated vaccine and the economical constraints of further industrial development.
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http://dx.doi.org/10.1186/s12977-019-0488-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6781361PMC
October 2019

Experimental infection of sheep with Bovine leukemia virus (BLV): Minimum dose of BLV-FLK cells and cell-free BLV and neutralization activity of natural antibodies.

Rev Argent Microbiol 2019 Oct - Dec;51(4):316-323. Epub 2019 Apr 22.

Instituto Nacional de Tecnología Agropecuaria (INTA) - Instituto de Virología, Centro de Investigaciones en Ciencias Veterinarias y Agronómicas, Nicolas Repetto y de los Reseros s/n (1686), Hurlingham, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Godoy Cruz 2290 (C1425FQB), CABA, Argentina.

Bovine leukemia virus (BLV) is an important cattle pathogen that causes major economic losses worldwide, especially in dairy farms. The use of animal models provides valuable insight into the pathogenesis of viral infections. Experimental infections of sheep have been conducted using blood from BLV-infected cattle, infectious BLV molecular clones or tumor-derived cells. The Fetal Lamb Kidney cell line, persistently infected with BLV (FLK-BLV), is one of the most commonly used long-term culture available for the permanent production of virus. FLK-BLV cells or the viral particles obtained from the cell-free culture supernatant could be used as a source of provirus or virus to experimentally infect sheep. In this report, we aimed to determine the minimum amount of FLK-BLV cells or cell-free supernatant containing BLV needed to produce infection in sheep. We also evaluated the amount of antibodies obtained from a naturally-infected cow required to neutralize this infection. We observed that both sheep experimentally inoculated with 5000 FLK-BLV cells became infected, as well as one of the sheep receiving 500 FLK-BLV cells. None of the animals inoculated with 50 FLK-BLV cells showed evidence of infection. The cell-free FLK-BLV supernatant proved to be infective in sheep up to a 1:1000 dilution. Specific BLV antibodies showed neutralizing activity as none of the sheep became infected. Conversely, the animals receiving a BLV-negative serum showed signs of BLV infection. These results contribute to the optimization of a sheep bioassay which could be useful to further characterize BLV infection.
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http://dx.doi.org/10.1016/j.ram.2019.01.004DOI Listing
May 2020

Short communication: Relationship between the level of bovine leukemia virus antibody and provirus in blood and milk of cows from a naturally infected herd.

J Dairy Sci 2016 Jul 4;99(7):5629-5634. Epub 2016 May 4.

Instituto de Virología, Centro de Investigaciones en Ciencias Veterinarias y Agronomicas, Instituto Nacional de Tecnología Agropecuaria, Buenos Aires, Argentina.

We explored the relationship between the level of bovine leukemia virus antibodies and provirus load during natural infection. For that purpose, a set of 50 blood and milk paired samples were analyzed for the presence of bovine leukemia virus provirus and antibodies. Additionally, provirus load and antibody titers were measured and the relationship between these variables was investigated. Bovine leukemia provirus was detected in 59% of milk samples and a negative correlation was observed between the level of milk provirus load and milk antibody titers. By the consumption of raw milk, calves might be exposed to bovine leukemia virus favoring the perinatal transmission of this disease.
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http://dx.doi.org/10.3168/jds.2015-10813DOI Listing
July 2016

[Mycobacterium bovis in wildlife of the dairy regions of Santa Fe (Argentina)].

Rev Argent Microbiol 2015 Jul-Sep;47(3):174-82. Epub 2015 Sep 14.

Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Agropecuaria Rafaela, Rafaela, Santa Fe, Argentina.

Control eradication campaigns of bovine tuberculosis based on the «test and slaughter» approach were successful in many countries and regions; however, in some areas the infection persists and one of the main reasons is Mycobacterium bovis infection in wild life species. Argentina has applied the same approach since 1999, achieving progress in dairy cattle herds. Nonetheless, the wildlife role has never been investigated. The objective of this study was to determine if wildlife from the Santa Fe dairy area is infected with M. bovis. Wildlife species having a positive tuberculin skin test were captured in five dairy farms. Ninety five wildlife mammals were captured; M. bovis was recovered from 7 possums (Didelphys albiventris), from one fox (Lycolapex gimnocercus) and from one rat (Rattus norvegicus). None of the animals exhibited macroscopic lesions. The most frequently isolated M. bovis spoligotypes were types 34 (4 isolates) and 12 (3 isolates). Spoligotype 34 is the most frequently isolated type in Argentine cattle. The role of D. albiventris as spillover host of M. bovis is discussed in this study.
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http://dx.doi.org/10.1016/j.ram.2015.04.005DOI Listing
February 2016

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

Virulence 2014 Feb 7;5(2):297-302. Epub 2014 Jan 7.

Biotechnology Institute; CICVyA-INTA; Castelar, Buenos Aires, Argentina.

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.
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http://dx.doi.org/10.4161/viru.27193DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3956505PMC
February 2014

Detection of Mycobacterium bovis-infected dairy herds using PCR in bulk tank milk samples.

Foodborne Pathog Dis 2012 Feb 27;9(2):132-7. Epub 2012 Jan 27.

Instituto de Biotecnología, Centro Nacional de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Castelar, Argentina.

Bovine tuberculosis (bTB) is a chronic and zoonotic disease due to Mycobacterium bovis. The tuberculosis eradication campaign carried out in Argentina has considerably improved the health situation of the herds. Here we evaluated a strategy to detect M. bovis-infected herds by Touch-Down IS6110 polymerase chain reaction (PCR) in bulk tank raw milk from dairy farms. We evaluated 177 samples from herds with the official tuberculosis free certificate (TFC) and 80 from herds without the certificate, non-tuberculosis-free certificate (NTFC), from 10 departments of Santa Fe province, Argentina. To avoid the effect of Taq polymerase inhibitors, a dilution of DNA template was performed. Positive PCR results were obtained in 102 (40%) of the samples, whereas negative ones were obtained in 155 (60%) of the samples. Importantly, 44% of NTFC and 38% of TFC samples were positive. All samples were subjected to culture in Löwenstein Jensen and Stonebrink media with no positive isolation. The negative predictive value (NPV) of PCR in the TFC group was 95%, while the positive predictive value (PPV) of PCR in the NTFC group was 51%. Based on these results, this work proposes a method that should be applied regularly to detect M. bovis--infected dairy herds, complementary to the official test of tuberculin, or purifed protein derivative (PPD), to control dairy herds, especially those free of tuberculosis.
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http://dx.doi.org/10.1089/fpd.2011.0963DOI Listing
February 2012

Use of touch-down polymerase chain reaction to enhance the sensitivity of Mycobacterium bovis detection.

J Vet Diagn Invest 2005 May;17(3):232-8

Instituto de Biotecnología, CICVyA/INTA, Los Reseros y las Cabañas, 1712 Castelar, Argentina.

The confirmatory diagnosis of Mycobacterium bovis (M. bovis) in animal samples is carried out by culture in Stonebrink media. However, culture is very slow because of the extremely long duplication time of the bacillus and difficult because of the scarcity of bacilli in diagnostic samples. This study describes the development of a single-tube touch-down polymerase chain reaction (PCR) protocol for the detection of M. bovis using primers that target the IS6110 element. Spiked water and milk as well as routine diagnostic samples (milk and nasal swabs) from M. bovis-positive cattle were tested. This protocol allows the rapid and sensitive detection of M. bovis in bovine samples by enhancing the sensitivity of standard PCR amplification.
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http://dx.doi.org/10.1177/104063870501700303DOI Listing
May 2005