Rotavirus Infection of Cells in Culture Induces Activation of RhoA and Changes in the Actin and Tubulin Cytoskeleton

Rotavirus infection induces an increase in [Ca2+]cyto, which in turn may affect the distribution of the cytoskeleton proteins in the infected cell. Changes in microfilaments, including the formation of stress fibers, were observed starting at 0.5 h.p.i. using fluorescent phalloidin. Western blot analysis indicated that RhoA is activated between 0.5 and 1 h.p.i. Neither the phosphorylation of RhoA nor the formation of stress fibers were observed in cells infected with virions pre-treated with an anti-VP5* non-neutralizing mAb, suggesting that RhoA activation is stimulated by the interaction of the virus with integrins forming the cell receptor complex. In addition, the structure of the tubulin cytoskeleton was also studied. Alterations of the microtubules were evident starting at 3 h.p.i. and by 7 h.p.i. when microtubules were markedly displaced toward the periphery of the cell cytoplasm. Loading of rotavirus-infected cells with either a Ca2+ chelator (BAPTA) or transfection with siRNAs to silence NSP4, reversed the changes observed in both the microfilaments and microtubules distribution, but not the appearance of stress fibers. These results indicate that alterations in the distribution of actin microfilaments are initiated early during infection by the activation of RhoA, and that latter changes in the Ca2+ homeostasis promoted by NSP4 during infection may be responsible for other alterations in the actin and tubulin cytoskeleton

Molecular Detection and Characterization of Aichi Viruses in Sewage-Polluted Waters of Venezuela▿

The circulation of Aichi virus in a major urban area was demonstrated using molecular detection with samples recovered from a major river polluted with sewage discharges in Caracas, Venezuela. Five out of 11 water samples studied were positive, being classified by phylogenetic analysis as genotype B. Analysis of sewage waters appears to be a useful methodology to uncover the presence of a hitherto undetected fecal pathogen in a given geographical area

Biología y evolución del coronavirus causante de la COVID-19

El nuevo coronavirus causante de la COVID-19 es llamado SARS-CoV-2 y pertenece al subgénero Sarbecovirus, como suantecesor el SARS-CoV. Los murciélagos parecen ser los hospederos de los virus ancestrales que los originaron, a través de la recombinacióncon el virus de un animal intermediario, que podría ser el pangolín. El SARS-CoV-2 interactúa con su receptor ACE2 (enzima convertidorade angiotensina 2) y entra a la célula por la vía endocítica, a través de un endosoma temprano o tardío. El ARN viral funge como ARNmensajero para la traducción del primer marco de lectura y el resto de los ARN mensajeros son producidos por transcripción discontinua.Esta peculiaridad le confiere a esta familia viral una alta frecuencia de recombinación, la cual está asociada con la alta frecuencia de saltode especie. Los virus pertenecientes al orden Nidovirales, al cual pertenece el SARS-CoV-2, son los únicos virus ARN conocidos cuyapolimerasa tiene actividad correctora, por lo que su tasa de mutación se ve reducida. Sin embargo, estos genomas parecen ser susceptiblesa la desaminación por enzimas celulares. Todos estos mecanismos de generación de diversidad se traducen en la existencia de linajes,entre los cuales, los que poseen la mutación D614G en la espiga, podrían ser más transmisibles. Sin embargo, no se conocen hasta la fechamutaciones asociadas a una mayor gravedad. Así como existen diferentes variantes virales, la manifestación clínica de la enfermedad estambién muy variable. Se empiezan a conocer algunos factores genéticos, fisiológicos y metabólicos que podrían estar determinando formasclínicas más graves, a menudo asociadas a la inmunopatología de esta enfermedad

Evaluation of Serum Antibody Responses against the Rotavirus Nonstructural Protein NSP4 in Children after Rhesus Rotavirus Tetravalent Vaccination or Natural Infection

The immune response elicited by the rotavirus nonstructural protein NSP4 and its potential role in protection against rotavirus disease are not well understood. We investigated the serological response to NSP4 and its correlation with disease protection in sera from 110 children suffering acute diarrhea, associated or not with rotavirus, and from 26 children who were recipients of the rhesus rotavirus tetravalent (RRV-TV) vaccine. We used, as antigens in an enzyme-linked immunosorbent assay (ELISA), affinity-purified recombinant NSP4 (residues 85 to 175) from strains SA11, Wa, and RRV (genotypes A, B, and C, respectively) fused to glutathione S-transferase. Seroconversion to NSP4 was observed in 54% (42/78) of the children who suffered from natural rotavirus infection and in 8% (2/26) of the RRV-TV vaccine recipients. Our findings indicate that NSP4 evokes significantly (P < 0.05) higher seroconversion rates after natural infection than after RRV-TV vaccination. The serum antibody levels to NSP4 were modest (titers of ≤200) in most of the infected and vaccinated children. A heterotypic NSP4 response was detected in 48% of the naturally rotavirus-infected children with a detectable response to NSP4. Following natural infection or RRV-TV vaccination, NSP4 was significantly less immunogenic than the VP6 protein when these responses were independently measured by ELISA. A significant (P < 0.05) proportion of children who did not develop diarrhea associated with rotavirus had antibodies to NSP4 in acute-phase serum, suggesting that serum antibodies against NSP4 might correlate with protection from rotavirus diarrhea. In addition, previous exposures to rotavirus did not affect the NSP4 seroconversion rate

Estudio de la infección por rotavirus y calicivirus en neonatos de la Maternidad “Concepción Palacios” de Caracas

En un estudio realizado en 1984 en la Maternidad &ldquo;Concepci&oacute;n Palacios&rdquo;, P&eacute;rez-Schael y col. detectaron excreci&oacute;n asintom&aacute;ti-ca de rotavirus en el 56% de los reci&eacute;n nacidos evaluados. El objetivo de este trabajo fue estudiar la infecci&oacute;n por rotavirus en neonatos de&nbsp;la Maternidad y comparar datos con aquellos obtenidos anteriormente. Adem&aacute;s, se investig&oacute; la presencia de calicivirus en dicha pobla-ci&oacute;n. Entre agosto y diciembre de 2004, se recolectaron 307 muestras de heces provenientes de 215 neonatos sanos. Para la detecci&oacute;n de&nbsp;los agentes virales se utilizaron ensayos tipo ELISA comerciales y no comerciales. Estos ensayos identificaron como positivas a rotavirus&nbsp;y calicivirus a un total de 14 y 58 muestras, respectivamente. Sin embargo, al realizar pruebas para corroborar la presencia de rotavirus&nbsp;por microscopia electr&oacute;nica, EGPA y RT-PCR y para calicivirus por RT-PCR, ninguna de las muestras se&ntilde;aladas como positivas pudo ser&nbsp;confirmada. Estos resultados sugieren la no-circulaci&oacute;n tanto de rotavirus como de calicivirus dentro de la Maternidad. Es posible que la&nbsp;interrupci&oacute;n de la transmisi&oacute;n de rotavirus dentro de la Instituci&oacute;n pueda deberse a cambios en el manejo del par madre-neonato introdu-cidos en la Maternidad desde 1995, promovidos por la OMS y UNICEF.&nbsp