Evolution of Dengue Virus Type 3 Genotype III in Venezuela: Diversification, Rates and Population Dynamics

<p>Abstract</p> <p>Background</p> <p>Dengue virus (DENV) is a member of the genus <it>Flavivirus </it>of the family <it>Flaviviridae</it>. DENV are comprised of four distinct serotypes (DENV-1 through DENV-4) and each serotype can be divided in different genotypes. Currently, there is a dramatic emergence of DENV-3 genotype III in Latin America. Nevertheless, we still have an incomplete understanding of the evolutionary forces underlying the evolution of this genotype in this region of the world. In order to gain insight into the degree of genetic variability, rates and patterns of evolution of this genotype in Venezuela and the South American region, phylogenetic analysis, based on a large number (<it>n </it>= 119) of envelope gene sequences from DENV-3 genotype III strains isolated in Venezuela from 2001 to 2008, were performed.</p> <p>Results</p> <p>Phylogenetic analysis revealed an <it>in situ </it>evolution of DENV-3 genotype III following its introduction in the Latin American region, where three different genetic clusters (A to C) can be observed among the DENV-3 genotype III strains circulating in this region. Bayesian coalescent inference analyses revealed an evolutionary rate of 8.48 × 10^-4substitutions/site/year (s/s/y) for strains of cluster A, composed entirely of strains isolated in Venezuela. Amino acid substitution at position 329 of domain III of the E protein (A→V) was found in almost all E proteins from Cluster A strains.</p> <p>Conclusions</p> <p>A significant evolutionary change between DENV-3 genotype III strains that circulated in the initial years of the introduction in the continent and strains isolated in the Latin American region in recent years was observed. The presence of DENV-3 genotype III strains belonging to different clusters was observed in Venezuela, revealing several introduction events into this country. The evolutionary rate found for Cluster A strains circulating in Venezuela is similar to the others previously established for this genotype in other regions of the world. This suggests a lack of correlation among DENV genotype III substitution rate and ecological pattern of virus spread.</p

Serotype-specific immune response against porcina rotaviruses

Se evaluó la respuesta inmunitaria serotipo específica contra rotavirus porcinos, en sueros de lechones y sueros hiperinmunes producidos en conejo, mediante un ELISA de competencia. El uso de una batería de 6 anticuerpos monoclonales (AcM) producidos contra la proteína VP7 de los serotipos G3, G5 o G11 y un AcM contra el segmento VP8* de la proteína VP4 del serotipo P9, permitió la identificación de tres grupos de reactividad. El primer grupo, representado por los AcM dirigidos a los serotipos G3 y G5, definido por el reconocimiento recíproco de los AcM 1C10 y 7D2 y, otro no recíproco por el AcM lC3. El segundo grupo de reactividad formado por los AcM de serotipo porcino Gil, definido por el reconocimiento recíproco de los AcM 6E10 y 8D10 y el no recíproco del AcM 5E6. El AcM 4B2, dirigido contra VP8*, representó el tercer grupo de reactividad. La respuesta inmunitaria en sueros hiperinmunes fue serotipo específica y apoyó la presencia de un epitope común sobre las VP7 G3 y G5 porcinas y de un dominio exclusivo sobre el serotipo Gl1 porcino. En lechones de 1 a 8 semanas de edad, se encontraron niveles considerables de anticuerpos que compitieron con el panel de AcM, sugiriendo que pudieran estar representados en el repertorio de anticuerpos que se producen por infección natural.114 - 118BimestralThe serotype-specific immune response against porcine rotaviruses was evaluated in piglets and hyperimmune sera raised in rabbits by a competition ELISA. Using 6 monoclonal antibodies (Mabs) directed against G3, G5 and G11 VP7 and one Mab directed against P9 VP8* cleavage product of VP4, three distinct reactivity group were identified: reactivity group represented porcine rotavirus serotypes G3 and G5, defined by the reciprocal recognition of 1C10 and 7D2 and by the nonreciprocal recognition of the Mab 1C3; represented porcine rotavirus G11, defined by the reciprocal recognition of Mab 6E10 and 8D10, and by the non-reciprocal recognition of Mab 5E6 and the one represented by Mab 4B2, directed against VP8*. In rabbit hyperimmune sera the immune response was serotype-specific and supported the presence of a commonepitope on both G3 and G5 VP7 types, as well as an exclusive domain for serotype G11. In 1- to 8-weeks old piglets, considerable levels of antibodies competed out all Mabs tested suggesting that the Mabs are represented in the antibody repertoire produced after natural infection of porcine rotavirus

Emergencia del Zika en tiempos de Dengue y Chikungunya

El virus Zika (VZIK) es un flavivirus transmitido a humanos por mosquitosdel g&eacute;nero Aedes. Este virus fue introducido a Am&eacute;rica del Suren 2014, generando una nueva epidemia por arbovirus de inesperadamagnitud y secuelas patol&oacute;gicas. El VZIK es un virus con envolturalip&iacute;dica, de genoma ARN de unos 10.000 pares de bases. Fue descubiertoen Uganda, donde probablemente se origin&oacute;, y fue introducido a variospa&iacute;ses africanos, as&iacute; como al Sur de Asia, generando dos linajes, unoafricano y uno asi&aacute;tico. Este &uacute;ltimo linaje fue el introducido a las Am&eacute;ricas,difundi&eacute;ndose de forma expansiva en la regi&oacute;n tropical. Aunque sepensaba inicialmente que la infecci&oacute;n por este virus ser&iacute;a menos severaque la causada por el virus dengue, el gran n&uacute;mero de casos ha permitidoconfirmar que la infecci&oacute;n por VZIK de mujeres embarazadas conduce agraves secuelas como la microcefalia y que la infecci&oacute;n en un porcentajesignificativo de casos causa ezl S&iacute;ndrome de Guillain Barre, una enfermedadautoinmune. No existe vacuna contra este virus, aunque el desarrollode una vacuna contra el virus dengue podr&iacute;a agilizar el desarrollo de unavacuna contra el VZIK. &nbsp

Detection of cross-reactive antibodies in sows vaccinated against porcine rotavirus strain OSU

Los rotavirus son los principales agentes virales productores de diarrea en lechones entre 3 a 6 semanas de edad, por lo que una de las principales estrategias para controlar la enfermedad es la vacunación de las madres antes del parto, con el fin de incrementar el efecto protector de los anticuerpos calostrales. En el presente trabajo se evaluó la respuesta inmunitaria contra cepas de rotavirus porcino (138, Gottfried, OSU, 253) y no porcino (WA, DS-1, RRV, NCDV) de diferentes serotipos P y G, en calostros y sueros sanguíneos de cerdas inmunizadas por vía parentelal, con una vacuna experimental oleosa monovalente contentiva de la cepa porcina OSU (P9, G5). Mediante pruebas de neutralización por reducción de focos infecciosos (NRFI) se demostró que la vacunación fue capaz de estimular la producción de anticuerpos contra los serotipos porcinos y no porcinos, de una manera eficiente y que esta respuesta puede estar dirigida contra los antígenos VP4 y/o VP7.292 - 298BimestralRotavirus are the principal cause of viral diarrhea in piglets of 3 to 6 weeks of age, because of that one strategie to control infection is vaccination of pregnant sows in order to increase the passive protection throug calostral antibodies. In the present study it was evaluated the antibody response to porcine (138, Gottfried, OSU, 253) and non-porcine (WA, DS-1, RRV, NCDV) rotaviral strains belonging to different P and G serotypes in calostrum and serum of sows immunized parenterally with an experimental monovalent oil-vaccine based on the porcine strain OSU (P9,G5). Neutralization by focus reduction assays showed that the vaccine induced high titer of neutralizing antibodies against the porcine and non-porcine serotypes by efficient way and this response could be directed against VP4 and/or VP7 antigens

Primer Pair p289-p290, Designed To Detect Both Noroviruses and Sapoviruses by Reverse Transcription-PCR, Also Detects Rotaviruses by Cross-Reactivity

A primer pair (p289-p290) designed to detect both noroviruses and sapoviruses by reverse transcription-PCR (Jiang et al., J. Virol. Methods 83:145, 1999) cross-reacts with rotaviruses. The rotavirus amplicon corresponds to genome segment 1. Furthermore, primer pair p289-p290 detected rotaviruses as efficiently as rotavirus-specific primers directed to rotavirus gene 4

Humoral inmune response against rotavirus in piglets

Se estudio la respuesta inmunitaria humoral contra rotavirus en 3 sueros de lechones gnotabioticos y 89 cerdos de granjas de diferentes edades, empleando la técnica de neutralización por reducción de focos fluorescentes (NRFF). En los lechones gnotibióticos, infectados con los rotavirus porcinos OSU (P7G5) o Gottfried (P6G4) se demostró que la respuesta es serotipo específica contra la cepa inmunizante y que está dirigida contra los 2 antígenos de neutralización VP4 y VP7. En lechones de granja, durante las dos primeras semanas de vida, la respuesta inmune es heterotípica contra las cepas porcinas y no porcinas. En animales de 3 a 8 semanas la prevalencia de anticuerpos para los rotavirus porcinos es menor y se produce como consecuencia de infección activa.117 - 124CuatrimestralThe humoral immune response against rotavirus in three gnotobiotic piglet sera and in 89 pig sera from different ages collected from different farms were studied by focus fluorescent neutralization assay (FFNA). The gnotobiotic piglets, infected with porcine rotavirus strain OSU (P9, G5) or Gottfried (P2B, G4), showed that humoral response is serotype-specific to the immunizing strain, besides being directed to both neutralization antigens, VP4 and VP7. On the other hand, the humoral response in piglets from any given farm was heterotypic (to porcine and no porcine strains) during the first 2 weeks of life. In animals, ranging from 3-8 weeks, prevalence of antibodies was lower to all porcine strains and was due to active infection

Bajo impacto de la infección silente por el virus de la hepatitis B en la incidencia de hepatitis postransfusional en Venezuela

Objetivo. Detectar la presencia de ADN del VHB en sueros de donantes de sangre negativos en las pruebas de los marcadores serológicos de hepatitis B empleados en el tamizaje, con el fin de evaluar el impacto de la infección silente por VHB sobre la incidencia de hepatitis B postransfusional en Venezuela. Métodos. Los sueros de 2 075 donantes de sangre negativos en las pruebas de los marcadores serológicos pesquisados en bancos de sangre venezolanos fueron analizados en 53 muestras, compuestas por la mezcla de 25-50 donaciones (0,5-1,0 mL de cada suero). Estas fueron sometidos a ultracentrifugación previa a la extracción del ADN viral por el método de proteinasa K-fenol-cloroformo. Resultados. En estas mezclas de sueros no se detectó ADN del VHB en ninguno de dos ensayos anidados de reacción en cadena de la polimerasa, mediante cebadores altamente conservados de las regiones que codifican el antígeno de superficie y de la cápside virales. Se observaron niveles normales de aminotransferasas en 98% de 200 sueros evaluados. Conclusiones. Estos resultados sugieren que el riesgo de adquirir hepatitis B postransfusional en Venezuela es bajo

Antibodies to Rotavirus Outer Capsid Glycoprotein VP7 Neutralize Infectivity by Inhibiting Virion Decapsidation

The rotavirus capsid is composed of three concentric protein layers. Proteins VP4 and VP7 comprise the outer layer. VP4 forms spikes, is the viral attachment protein, and is cleaved by trypsin into VP8* and VP5*. VP7 is a glycoprotein and the major constituent of the outer protein layer. Both VP4 and VP7 induce neutralizing and protective antibodies. To gain insight into the virus neutralization mechanisms, the effects of neutralizing monoclonal antibodies (MAbs) directed against VP8*, VP5*, and VP7 on the decapsidation process of purified OSU and RRV virions were studied. Changes in virion size were followed in real time by 90° light scattering. The transition from triple-layered particles to double-layered particles induced by controlled low calcium concentrations was completely inhibited by anti-VP7 MAbs but not by anti-VP8* or anti-VP5* MAbs. The inhibitory effect of the MAb directed against VP7 was concentration dependent and was abolished by papain digestion of virus-bound antibody under conditions that generated Fab fragments but not under conditions that generated F(ab′)(2) fragments. Electron microscopy showed that RRV virions reacted with an anti-VP7 MAb stayed as triple-layered particles in the presence of excess EDTA. Furthermore, the infectivity of rotavirus neutralized via VP8*, but not that of rotavirus neutralized via VP7, could be recovered by lipofection of neutralized particles into MA-104 cells. These data are consistent with the notion that antibodies directed at VP8* neutralize by inhibiting binding of virus to the cell. They also indicate that antibodies directed at VP7 neutralize by inhibiting virus decapsidation, in a manner that is dependent on the bivalent binding of the antibody