Abstract Bovine viral diarrhea virus (BVDV) is a pestivirus that infects a broad range of wild and domestic artiodactyls. Pestiviruses can cause a variety of respiratory, gastrointestinal and reproductive disorders that generate substantial losses in the livestock industry. Sharing of water and food sources between wild and domestic populations increases the risk of interspecies pestivirus transmission. Monitoring pestivirus prevalence in both population types is vital. No data is currently available on pestivirus genetic diversity in wild artiodactyl populations in Mexico. Isolation and genetic analysis were done for BVDV from serum samples collected from 371 captive wild artiodactyls in four regions in central and eastern Mexico. Samples from two water buffaloes and one fallow deer were positive for BVDV by RT-PCR. Phylogenetic analysis of the amplified sequences placed them in BVDV subgenotype 1b. A cytopathic strain was isolated from the deer sample. This is the first report of bovine viral diarrhea virus in wild artiodactyls in Mexico and the first to identify the virus subtype.

Resumen El virus de la diarrea viral bovina pertenece al género Pestivirus de la familia Flaviviridae. Los pestivirus infectan a un extenso rango de artiodáctilos, silvestres y domésticos, en los cuales ocasionan una gran variedad de desórdenes respiratorios, gastrointestinales y reproductivos que derivan en pérdidas relevantes para la industria pecuaria. El uso compartido de fuentes de agua y alimento entre los ambientes naturales y pecuarios incrementa el contacto directo e indirecto entre animales domésticos y silvestres, lo que aumenta el riesgo de transmisión interespecie de pestivirus. Por este motivo, la vigilancia de enfermedades causadas por pestivirus debería considerar la prevalencia de estos patógenos en animales silvestres. Actualmente se desconoce la diversidad genética de pestivirus en poblaciones silvestres en México. Este grupo de trabajo recolectó muestras de suero de 371 artiodáctilos silvestres en cautiverio en cuatro regiones de cuatro estados de México que incluyen a Veracruz, Querétaro, el Estado de México y la Ciudad de México. Dos muestras de suero de búfalas de agua y una muestra de suero de una gama fueron positivas al virus de la diarrea viral bovina mediante reacción en cadena de la polimerasa con transcripción reversa. El análisis filogenético de las secuencias amplificadas las agrupó dentro del subgenotipo 1b del virus de la diarrea viral bovina. Además, se logró el aislamiento de un virus citopático a partir de la muestra de suero de la gama. Este estudio constituye el primer reporte del virus de la diarrea viral bovina en artiodáctilos silvestres en México.

Abstract The study of the mechanisms used by different viruses to control host cell translation and favor the expression of viral proteins has been very instructive to know fundamental cellular mechanisms that regulate translation. Species A rotavirus (RVA) NSP3 protein is capable of inhibiting the translation of cellular mRNAs as a consequence of its binding to the translation initiation factor eIF4G and of stimulating the translation of viral mRNAs as a consequence of its binding to the UGACC sequence at their 3’-end. It has been proposed that NSP3 inhibits translation by interference with the circularization of the 5’-3’-ends of cellular mRNAs mediated by eIF4E-eIF4G-PABP (poly-A binding protein), and simultaneously it has been proposed that NSP3 stimulates translation of RVA mRNAs by circularization, in a way analogous to that performed by PABP on cellular mRNAs. However, the importance of NSP3 dimerization assisted by chaperone HSP90 in its inhibitory function of cell translation is unknown. Recently, the importance of NSP3 dimerization intermediates on its inhibitory function on host cell translation was explored, and it was found that point mutations in the coiled-coil region affect the formation of NSP3 dimers and partially preserve its host cell translation inhibitory function. In addition, it was found that NSP3 dimers degrade more rapidly than dimerization intermediates. These data demonstrate that the function of NSP3 is acquired prior to the appearance of dimers and suggests that the proteasome susceptibility of the different oligomeric forms of NSP3 are relevant in the establishment of the inhibitory function of cell translation.

Resumen El estudio de los mecanismos utilizados por diversos virus para controlar la traducción de la célula hospedera y favorecer la expresión de proteínas virales ha sido muy instructivo para conocer mecanismos celulares fundamentales que regulan la traducción. La proteína NSP3 de los rotavirus de la especie A (RVA) es capaz de inhibir la traducción de los RNAm celulares como consecuencia de su unión al factor de iniciación de la traducción eIF4G y de estimular la traducción de los RNAm virales como consecuencia de su unión a la secuencia UGACC de su extremo 3’. Se ha propuesto que NSP3 inhibe la traducción por interferir con la circularización de los extremos 5’-3’ de los RNAm celulares mediada por eIF4E-eIF4G-PABP (proteína de unión a poli-A), y simultáneamente se propone que NSP3 estimula la traducción de los RNAm del RVA circularizándolos de manera análoga a la que realiza PABP en los RNAm celulares. Sin embargo, la importancia de la dimerización de NSP3 asistida por la chaperona HSP90 en su función inhibitoria de la traducción celular se desconoce. Recientemente, se exploró la importancia de los intermediarios de la dimerización de NSP3 sobre su función inhibitoria de la traducción, y se encontró que mutaciones puntuales en la región coiled-coil afectan la formación de los dímeros y conservan parcialmente su función inhibitoria de la traducción celular. Además, se detectó que los dímeros de NSP3 se degradan con mayor rapidez que los intermediarios de la dimerización. Estos datos demuestran que la función de NSP3 se adquiere previamente a la aparición de los dímeros, y sugiere que la susceptibilidad al proteasoma de las distintas formas oligoméricas de NSP3 son relevantes en el establecimiento de la función inhibitoria de la traducción celular.

ABSTRACT Electron microscopy is routinely used to identify viral infections in protozoan parasites. These viruses have been described as non-enveloped and icosahedral structures with a diameter of 30-60 nm. Most of them are classified within the non-segmented dsRNA Totiviridae family. We observed virus-like particles (VLPs) through transmission electron microscopy in the cytoplasm of Trypanosoma cruzi epimastigotes grown in cultures. Clusters of electrodense enveloped VLPs having a diameter of 48 nm were also observed. These clusters appear to have been released from distended Golgi cisternae. Furthermore, a paracrystalline array of electrodense, non-enveloped VLPs (with a diameter of 32 nm) were found in distended Golgi cisternae or as smaller clusters at a distance from the RE or Golgi. We cannot rule out that the 48 nm enveloped VLPs belong to the ssRNA Flaviviridae family because they are within its size range. The localization of enveloped VLPs is consistent with the replication strategy of these viruses that transit through the Golgi to be released at the cell surface. Due to the size and shape of the 32 nm non-enveloped VLPs, we propose that they belong to the dsRNA Totiviridae family. This is the first description of cytoplasmic enveloped and non-enveloped VLPs in T. cruzi epimastigotes.

A hallmark of group/species A rotavirus (RVA) replication in MA-104 cells is the logarithmic increase in viral mRNAs that occurs four-12 h post-infection. Viral protein synthesis typically lags closely behind mRNA synthesis but continues after mRNA levels plateau. However, RVA non-structural protein 1 (NSP1) is present at very low levels throughout viral replication despite showing robust protein synthesis. NSP1 has the contrasting properties of being susceptible to proteasomal degradation, but being stabilised against proteasomal degradation by viral proteins and/or viral mRNAs. We aimed to determine the kinetics of the accumulation and intracellular distribution of NSP1 in MA-104 cells infected with rhesus rotavirus (RRV). NSP1 preferentially localises to the perinuclear region of the cytoplasm of infected cells, forming abundant granules that are heterogeneous in size. Late in infection, large NSP1 granules predominate, coincident with a shift from low to high NSP1 expression levels. Our results indicate that rotavirus NSP1 is a late viral protein in MA-104 cells infected with RRV, presumably as a result of altered protein turnover.

Rotavirus replication and virus assembly take place in electrodense spherical structures known as viroplasms whose main components are the viral proteins NSP2 and NSP5. The viroplasms are produced since early times after infection and seem to grow by stepwise addition of viral proteins and by fusion, however, the mechanism of viropIasms formation is unknown. In this study we found that the viroplasms surface colocalized with microtubules, and seem to be caged by a microtubule network. Moreover inhibition of microtubule assembly with nocodazole interfered with viroplasms growth in rotavirus infected cells. We searched for a physical link between viroplasms and microtubules by co-immunoprecipitation assays, and we found that the proteins NSP2 and NSP5 were co-immunoprecipitated with anti-tubulin in rotavirus infected cells and also when they were transiently co-expressed or individually expressed. These results indicate that a functional microtubule network is needed for viroplasm growth presumably due to the association of viroplasms with microtubules via NSP2 and NSP5.

Objective. To compare the severity of rotavirus diarrhea (RV) and non-rotavirus diarrhea. Material and Methods. Between October 1994 and March 1995, a cross-sectional study was performed in 520 infants with acute diarrhea, at seven primary care level centers in five states of Mexico. Diagnosis of RV was done through immunoenzymatic assay or electrophoresis. Central tendency measures were used for data analysis. Results were presented as means and standard deviations, or median and variation. Results. RV was isolated from 264 children; most of them were males aged 6 months to 1 year. Differences in clinical manifestations were statistically significant between the rotavirus-positive group and the rotavirus-negative group, in the following variables: median number of stools/24 hours; frequency of vomiting; temperature > 38°C; dehydration; and clinical severity scoring. Conclusions. These results showed a poorer prognosis and a higher severity of rotavirus diarrhea, as compared to non-rotavirus diarrhea in infants. The English version of this paper is available at: <A HREF="http://www.insp.mx/salud/index.html%20">http://www.insp.mx/salud/index.html </A>

Objetivo. Comparar la gravedad de la diarrea por rotavirus (RV) y por no rotavirus. Material y métodos. Estudio transversal en 520 lactantes con diarrea aguda, efectuado entre octubre de 1994 y marzo de 1995 en siete centros del primer nivel de atención en cinco estados de México. El diagnóstico de RV se realizó con ensayo inmunoenzimático o por electroforesis. El análisis se hizo a través de medidas de tendencia central. Los resultados se presentan como promedio y desviación estándar o mediana o variación. Resultados. Se aisló RV en 264 lactantes (50.7%) con predominio en varones de 6 meses a un año. Las manifestaciones clínicas fueron significativamente diferentes entre el grupo rotavirus positivo y el grupo rotavirus negativo en mediana de evacuaciones por 24 horas, frecuencia de vómitos, temperatura > 38° C, deshidratación y calificación de gravedad, respectivamente. Conclusiones. Estos resultados mostraron peor pronóstico por mayor gravedad de la diarrea por RV en lactantes, con relación a otra etiología. El texto completo en inglés de este artículo está disponible en: <A HREF="http://www.insp.mx/salud/index.html">http://www.insp.mx/salud/index.html</A>

Objective. To compare the severity of rotavirus diarrhea (RV) and non-rotavirus diarrhea. Material and Methods. Between October 1994 and March 1995, a cross-sectional study was performed in 520 infants with acute diarrhea, at seven primary care level centers in five states of Mexico. Diagnosis of RV was done through immunoenzymatic assay or electrophoresis. Central tendency measures were used for data analysis. Results were presented as means and standard deviations, or median and variation. Results. RV was isolated from 264 children; most of them were males aged 6 months to 1 year. Differences in clinical manifestations were statistically significant between the rotavirus-positive group and the rotavirus-negative group, in the following variables: median number of stools/24 hours; frequency of vomiting; temperature > 38°C; dehydration; and clinical severity scoring. Conclusions. These results showed a poorer prognosis and a higher severity of rotavirus diarrhea, as compared to non-rotavirus diarrhea in infants. The English version of this paper is available at: <A HREF="http://www.insp.mx/salud/index.html%20">http://www.insp.mx/salud/index.html </A>

Objetivo. Comparar la gravedad de la diarrea por rotavirus (RV) y por no rotavirus. Material y métodos. Estudio transversal en 520 lactantes con diarrea aguda, efectuado entre octubre de 1994 y marzo de 1995 en siete centros del primer nivel de atención en cinco estados de México. El diagnóstico de RV se realizó con ensayo inmunoenzimático o por electroforesis. El análisis se hizo a través de medidas de tendencia central. Los resultados se presentan como promedio y desviación estándar o mediana o variación. Resultados. Se aisló RV en 264 lactantes (50.7%) con predominio en varones de 6 meses a un año. Las manifestaciones clínicas fueron significativamente diferentes entre el grupo rotavirus positivo y el grupo rotavirus negativo en mediana de evacuaciones por 24 horas, frecuencia de vómitos, temperatura > 38° C, deshidratación y calificación de gravedad, respectivamente. Conclusiones. Estos resultados mostraron peor pronóstico por mayor gravedad de la diarrea por RV en lactantes, con relación a otra etiología. El texto completo en inglés de este artículo está disponible en: <A HREF="http://www.insp.mx/salud/index.html">http://www.insp.mx/salud/index.html</A>