Rogelio Alejandro Alonso Morales

Association between major histocompatibility complex microsatellites, fecal egg count, blood packed cell volume and blood eosinophilia in Pelibuey sheep infected with Haemonchus contortus

The objective of this study was to assess the correlation among traits associated with resistance or susceptibility to Haemonchus contortus infestation and to evaluate the participation of the ovine major histocompatibility complex (MHC) in Pelibuey sheep, a prevalent breed in tropical and sub-tropical regions in Mexico and elsewhere. Association among the fecal egg count (FEC), blood packed cell volume (PCV), antibody (AB) levels, serum proteins (SP) and blood eosinophil count (EOS) was assessed in 52 lambs experimentally infected with H. contortus, and the participation of the MHC was evaluated using polymorphisms in three microsatellites, located at the class I (OMHC1) and class II (OLADRB1, OLADRB2) regions of the MHC. Spearman correlation analysis among the traits showed a negative association (P<0.01) between FEC and PCV (-0.35), EOS (-0.50), SP (-0.30) and AB (-0.57), and a positive correlation of antibodies with EOS (0.50). The homozygotes for the OMHC1-188 and OLADRB2-282 alleles were associated with a reduction in FEC (-813 and -551, respectively). Conversely, the OMHC1-200 and OMHC1-206 alleles were associated with an increase in FEC (1704 and 1008, respectively). Furthermore, the OLADRB1-482 allele was associated with an increase of 163 EOS by allele copy, while the OMHC1-200 allele showed a reduction of 95 EOS in homozygotes. The associations among microsatellite MHC loci and the remaining variables were not significant. These results reinforce the evidence that MHC polymorphisms have an important role in parasite resistance or susceptibility in Pelibuey sheep and could be used as genetic markers to assist selection and improve parasite resistance to H. contortus.

Polymorphism of locus DRB3.2 in populations of Creole Cattle from Northern Mexico

The polymorphism of locus BoLA-DRB3.2 of the Major Histocompatibility Complex was evaluated in two northern Mexican Creole cattle populations, Chihuahua (n = 47) and Tamaulipas (n = 51). The BoLA-DRB3.2 locus was typed by amplification and digestion with restriction endonuclease enzymes (PCR-RFLP). Fifty-two alleles were detected (28 previously reported and 24 new ones). In the Chihuahua population, 18 alleles and 5.5 effective alleles were found, while in the Tamaulipas population there were 34 and 10.8, respectively. The allele frequencies ranged from 0.011 to 0.383 in Chihuahua and from 0.010 to 0.206 in Tamaulipas. The frequencies of the new alleles in both cattle populations were low (0.010 to 0.053). The expected heterozygosity was 0.827 and 0.916, respectively, for the Chihuahua and Tamaulipas populations. Both populations presented a heterozygote deficit: [Chihuahua FIS = 0.1 (p = 0.019) and Tamaulipas FIS = 0.317 (p < 0.001)]. In conclusion, this study showed that the Mexican Creole cattle have many low-frequency alleles, several of which are exclusive to these populations. Genetic distances obtained show that the Mexican Creole cattle population is composed of independent populations, far apart from other South American Creole populations.

Genetic polymorphism of the αs1-casein locus in five populations of goats from Mexico

Electronic Journal of Biotechnology ISSN: 0717-3458 Vol.11 No.3, Issue of July 15, 2008

Immunogenic peptides from phage display libraries with potential of protecting mice against the Pseudorabies virus.

Phage display selection of combinatorial peptide libraries has demonstrated its almost unlimited potential in identifying binding ligands for many targets. The method shows promise for selection of immunogenic peptides against pathogens by antibodies. We have undertaken a study designed to select such mimics for one of the representatives of Herpesviridae, the Pseudorabies virus (PrV), infecting pigs and causing severe neurological complications known as Aujeszkys disease. By screening a 12mer linear and a 7mer cysteine-constrained libraries with immunoglobulins of a rabbit immunized with the virus, a family of 10 antigenic and immunogenic peptides was derived sharing a sequence motif K(L/P/V)GDP(R/K/L). Groups of six C57BL/6 mice were immunized with bacteriophages expressing peptides with this motif sequences. Some of the mice were found to be positive in seroneutralization assay; in a challenge setting, all but two immunized mice survived, albeit presenting some disease symptoms. We discuss the perspectives and limits of generating peptide leads by library screening with immune polyclonal antiserum for designing pure epitope-based vaccines to PrV in the future.

Evaluation of metabolic, endrocrine and growth features in the Mexican hairless pig to determinate its potential as model for obesity in comparison with commercial pigs

Biochemical, endocrine and growth performance variables were evaluated and compared in the Mexican hairless (MHP) and in Landrace Yorkshires pigs (LYP) from first to ninth month of age in order to establish if the MHP could be a better model for the study of obesity than the LYP. Serum concentrations of total cholesterol (TC), triglycerides (TG), high-density lipoproteins (HDL), low-density lipoproteins (LDL), glucose, free fatty acids (FFA), and insulin were measured. Feed intake, body weight and backfat thickness were also monitored. The results showed that the MHP partitioned more energy to backfat than the LYP (P<0.01), and had higher fasting serum concentrations of insulin, TC, TG, LDL, and FFA than the LYP (P<0.05). Based on the high capacity of the MHP to deposit body fat, and its higher serum concentrations of insulin, TG, CT, LDL, and FFA, we conclude that the MHP is a better model for the study of obesity than the Landrace-Yorkshire pigs and could be used under experimental conditions as a model for obesity, particularly the observed in metabolically healthy but obese humans.

Identification and genotyping of porcine circovirus type II (PCV2) in Mexico

Porcine circovirus type 2 (PCV2), family Circoviridae, genus Circovirus infection in domestic pig has been associated with several pathological conditions being the most important of them the postweaning multisystemic wasting syndrome. Many studies have demonstrated the existence of three PCV2 genotypes (a, b, and c) and recently PCV3. Until now, these genotypes or subgenotypes have not been described in Mexico. We found genetic changes in ORF2 from nine strains of PCV2 obtained from samples of Jalisco, Veracruz, Estado de México, Hidalgo and Sonora states of Mexico. Our results shown the presence of two genotypes (PCV2a and PCV2b) as well as, the presence and differences between the reported subgenotypes. The subgenotype PCV2b (1A/1B, 1A) has a higher prevalence (87.5%) in comparison with PCV2a (2C) (12.5%).

Phylogenetic Relationships and Acaricidal Effects of Beauveria bassiana Obtained from Cattle Farm Soils Against Rhipicephalus microplus

Abstract The objectives of the present study were to isolate Beauveria bassiana strains from cattle farm soils, analyze the phylogenetic relationships among the fungal strains isolated from these soils, and determine the acaricidal effect of B. bassiana isolates on engorged Rhipicephalus microplus tick strains resistant or susceptible to chemical acaricides. Six strains of B. bassiana were obtained and isolated from cattle farm soils in the Mexican tropics using the Galleria bait method, and their acaricidal effect was assessed against 2 populations of R. microplus (“Media Joya” chemical acaricide-resistant strain or “CLAR” chemical acaricide-susceptible strain) using the adult immersion test. The BbV03 strain produced 86.7% and 60% mortality in resistant and susceptible ticks on day 20, respectively, whereas the BbV04 strain produced 66.7% and 53.5% mortality in resistant and susceptible ticks on day 20, respectively. The BbV03 and BbV04 strains reduced egg laying on both R. microplus populations. There was no statistical difference in the acaricidal effect of B. bassiana strains among chemical acaricide-susceptible or -resistant R. microplus populations (P > 0.05). The BbV03 strain was the most virulent against R. microplus with an LC50 of 2 × 107 and LC99 of 7 × 108 conidia/ml. We found that the 6 B. bassiana isolated clustered in the same clade with other previously reported B. bassiana strains (from GenBank) but were separated into 3 different sub-clades. This study shows that some B. bassiana strains are a promising coadjuvant alternative for biological tick control, including tick populations that are resistant to chemical acaricides. Beauveria bassiana is present in the pastures of tropic cattle farms, and there are genetic variations between B. bassiana strains living in this ecosystem that might play an important role in the natural control of R. microplus in cattle farm paddocks.