Prevalencia, distribución y caracterización molecular de los virus de las encefalitis equinas del este, oeste y venezolana en Costa Rica
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Fecha
2023
Tipo
tesis doctoral
Autores
León Rodríguez, Bernal Alberto
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Resumen
Los virus de las encefalitis equinas del Este (EEEV), Oeste (WEEV) y Venezolana (VEEV)
pertenecen al género Alfavirus, familia Togaviridae, son agentes zoonóticos, que ocasionan
infecciones importantes desde Norte América, Centro América, las islas del Caribe y
Sudamérica (Aguilar et al., 2011; Figueiredo, 2007; Strauss & Strauss, 1994). En Costa
Rica producen brotes periódicos en diferentes regiones del país. Estos brotes afectan
principalmente a equinos y esporádicamente a seres humanos Este estudio se centró en los
dos Alfavirus que mostraron estar presentes en el país, el EEEV y el VEEV. En la primera
parte del proyecto se confirmó la presencia, prevalencia y distribución geográfica de estos
virus, así como la frecuencia con que se presentan los casos o brotes y posibles patrones de
estacionalidad y factores de riesgo asociados a estas infecciones, basados en dos estudios
serológicos uno de tipo transversal y otro longitudinal. Ambos estudios se llevaron a cabo a
partir de ELISAs para la detección de IgG, IgM y pruebas de neutralización viral.
En la segunda parte del proyecto realizó un análisis filogenético, para conocer las
relaciones evolutivas entre los diferentes subtipos del complejo I del VEEV, se estableció
el origen y el tiempo de los ancestros comunes más recientes (TMRCA), además de
identificar posibles mutaciones asociadas con la patogénesis del VEEV. Para ello se
compararon pruebas de RT-PCR universales descritas previamente para seleccionar el
mejor RT-PCR en términos de sensibilidad y especificidad, se implementaron métodos de
secuenciación de Sanger y de nueva generación, y se utilizaron programas bioinformáticos
y bases de datos. Finalmente, en la tercera etapa del estudio se generó un modelo de nicho
usando el programa MaxEnt que permitió identificar áreas geográficas dónde pueden
ocurrir nuevos brotes del VEEV a partir de datos de presencia de VEEV establecidos en
este estudio.
The Eastern (EEEV), Western (WEEV), and Venezuelan (VEEV) equine encephalitis viruses belong to the genus Alphavirus, family Togaviridae, these are zoonotic agents that cause significant infections in North America, Central America, the Caribbean islands, and South America (Aguilar et al., 2011; Figueiredo, 2007; Strauss & Strauss, 1994). In Costa Rica, they produce periodic outbreaks in different regions of the country. These outbreaks mainly affect horses and sporadically humans. This study focused on the two Alphaviruses that were shown to be present in the country, EEEV, and VEEV. The first part of the project confirmed the presence, prevalence, and geographical distribution of these viruses, as well as the frequency of cases or outbreaks and possible seasonality patterns and risk factors associated with these infections, based on two serological studies, one cross sectional and the other longitudinal. Both studies were carried out using ELISAs for the detection of IgG, IgM, and viral neutralization tests. In the second part of the project, a phylogenetic analysis was performed to determine the evolutionary relationships between the different subtypes of VEEV complex I, to establish the origin and the time of the most recent common ancestors (TMRCA), and to identify possible mutations associated with the pathogenesis of VEEV. For this purpose, previously described universal RT-PCR tests were compared to select the best RT-PCR in terms of sensitivity and specificity, Sanger and next-generation sequencing methods were implemented, and bioinformatics programs and databases were used. Finally, in the third stage of the study, a niche model was generated using the MaxEnt program that allowed the identification of geographic areas where new VEEV outbreaks may occur from VEEV presence data established in this study.
The Eastern (EEEV), Western (WEEV), and Venezuelan (VEEV) equine encephalitis viruses belong to the genus Alphavirus, family Togaviridae, these are zoonotic agents that cause significant infections in North America, Central America, the Caribbean islands, and South America (Aguilar et al., 2011; Figueiredo, 2007; Strauss & Strauss, 1994). In Costa Rica, they produce periodic outbreaks in different regions of the country. These outbreaks mainly affect horses and sporadically humans. This study focused on the two Alphaviruses that were shown to be present in the country, EEEV, and VEEV. The first part of the project confirmed the presence, prevalence, and geographical distribution of these viruses, as well as the frequency of cases or outbreaks and possible seasonality patterns and risk factors associated with these infections, based on two serological studies, one cross sectional and the other longitudinal. Both studies were carried out using ELISAs for the detection of IgG, IgM, and viral neutralization tests. In the second part of the project, a phylogenetic analysis was performed to determine the evolutionary relationships between the different subtypes of VEEV complex I, to establish the origin and the time of the most recent common ancestors (TMRCA), and to identify possible mutations associated with the pathogenesis of VEEV. For this purpose, previously described universal RT-PCR tests were compared to select the best RT-PCR in terms of sensitivity and specificity, Sanger and next-generation sequencing methods were implemented, and bioinformatics programs and databases were used. Finally, in the third stage of the study, a niche model was generated using the MaxEnt program that allowed the identification of geographic areas where new VEEV outbreaks may occur from VEEV presence data established in this study.
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Palabras clave
COSTA RICA, VIRUS, MOLECULAS, PREVALENCIA, DISTRIBUCIÓN, CARACTERIZACIÓN