José Iván Sánchez-Betancourt

Identification of Antigenic Variants of the Porcine Rubulavirus in Sera of Field Swine and their Seroprevalence

We sampled sera from 1013 non-vaccinated swine from four states in Mexico, Guanajuato, Jalisco, Michoacán and the Estado de Mexico, to analyse anti-porcine rubulavirus antibody titres against three different porcine rubulavirus isolates (PAC-4/1993, PAC-6/2001, and PAC-9/2003) using a hemagglutination inhibition assay. The results revealed that there were antigenic differences among the isolates assessed. In particular, the estimated correlation between the PAC-4/1993 and PAC-6/2001 (0.50) isolates and between the PAC-4/1993 and PAC-9/2003 isolates (0.56) displayed a moderate positive correlation. In contrast, there was a strong positive correlation between the PAC-6/2001 and PAC-9/2003 isolates (0.73). We also found that in the state of Guanajuato, PAC-4/1993 was the isolate that was most frequently identified; in Jalisco, the isolate was PAC-6/2001; and in Michoacán, the isolate was PAC-9/2003. By contrast, in the Estado de Mexico, all three isolates appeared to circulate with a low seroprevalence. In general, the analysed sera from the four states displayed a porcine rubulavirus serological prevalence ranging from 9% to 23.7%. These data indicate that there is not complete antibody cross-antigenicity among the three isolates, and the antigenic variations in the antibody response found in this study implies that the use of a monovalent vaccine would not generate complete protection against the different antigenic subtypes.

Seroprevalence of anti-hepatitis E virus antibodies in domestic pigs in Mexico

BackgroundHepatitis E virus (HEV) infection is one of the most common causes of acute liver diseases in humans worldwide. In developing countries, HEV is commonly associated with waterborne outbreaks. Conversely, in industrialized countries, HEV infection is often associated with travel to endemic regions or ingestion of contaminated animal products. Limited information on both, human and animal HEV infection in Mexico is available. As a consequence, the distribution of the virus in the country is largely unknown. Here, we assessed the seroprevalence of HEV among swine in different geographical regions in Mexico.MethodsSeroprevalence of anti-HEV antibodies in swine herds in Mexico was evaluated in a representative sample including 945 pig serum specimens from different regions of the country using a commercial enzyme-linked immunosorbent assay (ELISA).ResultsThe overall prevalence of anti-HEV antibodies in swine was 59.4%. The northern region of Mexico exhibited the highest seroprevalence in the country (86.6%), while the central and southern regions in Mexico showed lower seroprevalence, 42.7% and 51.5%, respectively.ConclusionsIn Mexico, HEV seroprevalence in swine is high. Importantly, northern Mexico showed the highest seroprevalence in the country. Thus, further studies are required to identify the risk factors contributing to HEV transmission among pigs in the country. Assessment of HEV human infection in the context of viral transmission in swine is required to better understand the epidemiology of hepatitis E in Mexico.

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%).

Molecular characterization of the ORF2 of Torque teno sus virus 1a and Torque teno sus virus 1b detected in cases of postweaning multisystemic wasting syndrome in Mexico

Worldwide Torque teno sus virus (TTSuV, genus Iotatorquevirus) species have been regarded as possible agents associated with porcine circovirus-associated disease. Iotatorquevirus species possess high genomic variability, suggesting that diverse genotypes are widely geographically distributed. In this study, we validated the genomic variability of Iotaroquevirus species in pigs with postweaned multisystemic wasting syndrome. Genomic DNA from nine TTSuV1a-positive tissues and 15 TTSuV1b-positive tissues was used to amplify the complete ORF2 of each species by nested PCR to perform a molecular characterization. It was found that Mexican TTSuV1a sequences belong to genotype B, sharing phylogenetic origin, high nucleic acid and amino acid sequence similarity and dominant epitope conformation with commercially linked countries, such as the United States, Canada and China, whereas the Mexican TTSuV1b sequences belong to genotype A, being more divergent among each other and displaying low nucleotide identity with worldwide genotype A sequences. In both Iotatorquevirus species, a PTPase-like signature motif was identified in the predicted amino acid sequence, being more conserved for Mexican TTSuV1b sequences than for Mexican TTSuV1a sequences, in which several substitutions were observed. These changes may influence the conformation of dominant epitopes as different arrays were determined among TTSuV1a genotypes. ORF2 variability may account for pathogenic differences by modifying viral replication and immune response, as depicted for human TTV.

Identification and genomic characterization of influenza viruses with different origin in Mexican pigs

Swine influenza is a worldwide disease, which causes damage to the respiratory system of pigs. The H1N1 and H3N2 subtypes circulate mainly in the swine population of Mexico. There is evidence that new subtypes of influenza virus have evolved genetically and have been rearranged with human viruses and from other species; therefore, the aim of our study was to identify and characterize the genetic changes that have been generated in the different subtypes of the swine influenza virus in Mexican pigs. By sequencing and analyzing phylogenetically the eight segments that form the virus genome, the following subtypes were identified: H1N1, H3N2, H1N2 and H5N2; of which, a H1N1 subtype had a high genetic relationship with the human influenza virus. In addition, a H1N2 subtype related to the porcine H1N2 virus reported in the United States was identified, as well as, two other viruses of avian origin from the H5N2 subtype. Particularly for the H5N2 subtype, this is the first time that its presence has been reported in Mexican pigs. The analysis of these sequences demonstrates that in the swine population of Mexico, circulate viruses that have suffered punctual-specific mutations and rearrangements of their proteins with different subtypes, which have successfully adapted to the Mexican swine population.

Phylogenetic analysis of ORF5 and ORF7 of porcine reproductive and respiratory syndrome (PRRS) virus and the frequency of wild-type PRRS virus in México

Porcine reproductive and respiratory syndrome (PRRS) is caused by a genetically diverse RNA virus and is an economically significant disease in the swine industry. In this study, a total of 8,126 serum samples were obtained from 275 technified and semi-technified farms belonging to 30 of the 32 states of Mexico and representative of the eight regions of the country. Anti-PRRSv antibodies against the PRRS vaccine and an isolated wild Mexican virus were tested by ELISA. Antibodies were found in 15%-49% of the tested sera, with 2.4%-9.8% against the vaccine and 7.7%-26% against the wild virus. The PRRSv virus was detected by RT-PCR in 77 of the 1,630 pooled samples tested, representing seven of the eight geographic regions into which the Mexican Republic is divided. The complete sequences of open reading frames 5 and 7 from 20 PRRSv-positive samples were determined. The analysis of the sequences together with the previously published sequences of historic strains revealed that all the strains belonged to the one, five and eight lineages of the PRRSV2. Striking differences, particularly in ORF5 and ORF7, were found between sequences of the strains and the reference virus, due to insertions and substitutions in positions that play key roles in the recognition, structure and function of the virus. Overall, these results established the magnitude of PRRS virus genetic diversity, and the most frequent virus strain that predominates in Mexico. The PRRSV2 is presented in the porcine population of Mexico; the circulating strains have important changes in ORF5 and ORF7, which probably explain the results obtained in the serological analysis of the wild virus and vaccine strains.