Assembly and Analysis of Haemonchus contortus Transcriptome as a Tool for the Knowledge of Ivermectin Resistance Mechanisms

Haemonchus contortus (Hc) is an important parasitic nematode of small ruminants. In this study we assembled the transcriptome of Hc as a model to contribute to the knowledge about the profile of the differential gene expression between two Mexican Hc strains under different anthelmintic resistance statuses, one susceptible and the other resistant to ivermectin (IVMs and IVMr, respectively), in order to improve and/or to have new strategies of control and diagnosis. The transcript sequence reads were assembled and annotated. Overall, ~127 Mbp were assembled and distributed into 77,422 transcript sequences, and 4394 transcripts of the de novo transcriptome were matched base on at least one of the following criteria: (1) Phylum Nemathelminthes and Platyhelminthes, important for animal health care, and (2) ≥55% of sequence identity with other organisms. The gene ontology (GO) enrichment analysis (GOEA) was performed to study the level of gene regulation to IVMr and IVMs strains using Log Fold Change (LFC) filtering values ≥ 1 and ≥ 2. The upregulated-displayed genes obtained via GOEA were: 1993 (for LFC ≥ 1) and 1241 (for LFC ≥ 2) in IVMr and 1929 (for LFC ≥ 1) and 835 (for LFC ≥ 2) in IVMs. The enriched GO terms upregulated per category identified the intracellular structure, intracellular membrane-bounded organelle and integral component of the cell membrane as some principal cellular components. Meanwhile, efflux transmembrane transporter activity, ABC-type xenobiotic transporter activity and ATPase-coupled transmembrane transporter activity were associated with molecular function. Responses to nematicide activity, pharyngeal pumping and positive regulation of synaptic assembly were classified as biological processes that might be involved in events related to the anthelmintic resistance (AR) and nematode biology. The filtering analysis of both LFC values showed similar genes related to AR. This study deepens our knowledge about the mechanisms behind the processes of H. contortus in order to help in tool production and to facilitate the reduction of AR and promote the development of other control strategies, such as anthelmintic drug targets and vaccines.

Effect of entomopathogenic native fungi from paddock soils against Rhipicephalus microplus larvae with different toxicological behaviors to acaricides

The objectives of this study are to: (1) evaluate the in vitro acaricidal effect of 54 Metarhizium anisopliae strains, six Beauveria bassiana strains and one Purpureocilium lilacinum strain, against the larvae of two populations of Rhipicephalus microplus (multi-resistant and susceptible to chemical acaricides); and (2) determine the lethal concentrations required to eliminate the 50% (LC50) and 99% (LC99) of larvae through the use of entomopathogenic fungi (EF) with high acaricidal effects. The mortality percentage was evaluated by larval immersion tests at a dose of 1 × 10⁸ conidia/mL for each fungal strain. For calculating LC50 and LC99, four doses (1 × 10⁸, 1 × 10⁷, 1 × 10⁶ and 1 × 10⁵) were used. Nine strains of M. anisopliae and the P. lilacinum strain showed a high mortality percentage in the R. microplus larvae of both populations. The best strains that showed the lowest values of LC50 and LC99 for tick elimination were MaV50 and PlV01. In conclusion, several strains of entomopathogenic fungi showed a high acaricidal effect against the R. microplus larvae of both populations, suggesting that these fungi might be a promissory adjuvant in the control of R. microplus, including those who are resistant. Finally, the discovery of a P. lilacinum strain with a high acaricidal effect is also reported.

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.

Evaluación de una vacuna de ADN y su péptido recombinante contra inhibina alfa (165-300) sobre la respuesta inmune y fertilidad en ratones

Se evalúo la vacuna de ADN (INHA-DNA) y su péptido recombinante (INHA-rec) contra inhibina alfa (INHA) sobre la respuesta inmune y la fertilidad en ratones. Dieciséis ratones Balb/c fueron divididos en dos grupos, 8 cada uno. Bajo un esquema de inmunización prime boost heterólogo, un grupo fue inoculado vía intramuscular (IM) con 100 µg de INHA-DNA y 14 d después con 100 µg de INHA-rec. El grupo control recibió solución salina. Se aparearon las hembras en dos ocasiones. Posterior al primer parto se dio un refuerzo vía IM con ambos inmunógenos (100 µg INHA-DNA + 100 µg INHA-rec). La inmunización con 100 µg de INHA-DNA y INHA-rec indujo altos niveles de anticuerpo anti INHA, mayor tamaño y peso de camada (P<0.05) comparados con el control. La fertilidad promedio fue similar entre los tratados (67%) y control (60%). En conclusión, la vacuna de ADN y su antígeno recombinante es capaz de inducir títulos de anticuerpos contra INHA incrementando el tamaño de camada, sin un efecto negativo sobre la fertilidad en ratones. 

Acaricidal activity of Metarhizium anisopliae isolated from paddocks in the Mexican tropics against two populations of the cattle tick Rhipicephalus microplus

The acaricidal effects of 55 strains of Metarhizium anisopliae (Metschnikoff) Sorokin, 1883 (Hypocreales: Clavicipitaceae) isolated from paddocks of cattle farms were evaluated in two Rhipicephalus microplus (Canestrini 1887) (Ixodida: Ixodidae) populations, of which one was multi-resistant and one was susceptible to chemical acaricides. Percentage mortality and reproductive efficiency indices in R. microplus were evaluated by adult immersion tests at a dose of 1 × 10⁸ conidia/mL for each fungal strain. Some strains were selected to calculate lethal concentrations to kill 50% (LC₅₀ ) and 99% (LC₉₉ ) of engorged ticks. Strains MaV22, MaV26 and MaV55 induced 100% mortality in R. microplus on day 14. Strains MaV05, MaV09 and MaV22 caused mortality of >90% from day 12 onward in both tick populations. The most effective acaricidal fungal strain, MaV55, inhibited egg laying by 54.86 and 55.86% in acaricide-resistant and -susceptible R. microplus populations, respectively. None of the fungal strains had statistically significant effects on larval hatching. In conclusion, nine strains of M. anisopliae demonstrated high acaricidal effects against R. microplus and reduced its egg laying. No differences in acaricidal effects were observed between the two populations of ticks tested.

Síndrome reproductivo y respiratorio del cerdo (PRRS)

El síndrome reproductivo y respiratorio del cerdo (PRRS), es una enfermedad de origen viral que ocasiona fallas reproductivas severas en cerdas gestantes, con menos grado en la calidad del semen en verracos y problemas respiratorios en cerdos de todas las edades pero  principalmente en lechones; también se asocia o incrementa la manifestación de otras enfermedades respiratorias. Es una de las enfermedades de mayor importancia económica mundial, en la mayoría de los países de producción de porcinos, donde en gran parte de ellos permanece endémico. El virus de PRRS (PRRSV) presenta un alto grado de mutabilidad, por lo que hay una gran diversidad genética de cepas del linaje norteamericano (PRRSV NA) y entre el PRRSV NA y el linaje europeo (PRRSV EU), lo que afecta la homogeneidad y poca o nula antigenicidad cruzada para vacunas; el virus vacunal modificado, único comercialmente accesible para generar algún grado confiable de inmunidad, ha mostrado la capacidad de revertirse a patógeno, con replicabilidad y recombinación con virus de campo; las vacunas sólo se utilizan para disminuir el grado de afección de la enfermedad; el virus muestra una capacidad de  inmunosupresión e inmunoregulación que le permite, prolongar el tiempo de viremia en los animales enfermos, quienes eliminan el virus por saliva, secreciones transplacentarias, mamarias y muy posiblemente excremento, siendo la transmisión principal por contacto directo o por objetos  contaminados; además presenta una posterior selectividad a pocos tejidos linfoides, que le permite permanecer inadvertido hasta que, en condiciones favorables, vuelve a manifestarse la enfermedad, ya sea como pequeños brotes, o como pandemia.