Dengue virus infection induces chromatin remodeling at locus AAEL006536 in the midgut of Aedes aegypti / La infección por virus dengue induce remodelación de la cromatina en el locus AAEL006536 en el intestino medio de Aedes aegypti

Abstract: Objective: To identify and characterize Aedes aegypti's AAEL006536 gene proximal upstream cis-regulatory sequences activated by dengue virus infection. Materials and methods: A. aegypti Rockefeller strain mosquitoes were blood fed or infected with dengue virus 2. Open chromatin profiling was then carried out in pools of midguts from each group of mosquitoes. Results: The proximal upstream region does not contain open chromatin sites in the midguts of blood-fed mosquitoes as detected by FAIRE-qPCR. In contrast, two cis-regulatory sites were identified in the same upstream region of dengue virus-infected mosquito midguts. The distal sequence contains STAT-, REL- and C/EBP-type transcription factor binding sites. Conclusion: The activation of two proximal cis-regulatory sequences, induced by dengue virus infection, is mediated by chromatin remodeling mechanisms. Binding sites suggest a dengue virus infection-induced participation of immunity transcription factors in the up-regulation of this gene. This suggests the participation of the AAEL006536 gene in the mosquito's antiviral innate immune response.

Resumen: Objetivo: Identificar y caracterizar las secuencias reguladoras activadas por la infección por virus dengue en la región proximal del gen AAEL006536 de Aedes aegypti. Material y métodos: Mosquitos de la cepa Rockefeller de A. aegypti se infectaron con virus dengue o se alimentaron con sangre. Se obtuvieron los perfiles de cromatina abierta del locus en los intestinos de cada uno de los grupos. Resultados: Se identificaron dos sitios reguladores solo en los intestinos de mosquitos infectados por virus dengue. El sitio distal contiene sitios de unión a factores de transcripción tipo REL, STAT y C/EBP. Conclusiones: La activación de dos sitios reguladores proximales está mediada por la remodelación de la cromatina. Los sitios de unión a factores de transcripción en el sitio regulador distal sugieren la participación de las vías de inmunidad en la regulación del gen. Esto sugiere la participación de este gen en la respuesta inmune del mosquito frente a la infección viral.

HPV infection, risk factors and viral load among Mexican male college students

Objectives: To determine the prevalence of HPV and the risky sexual behaviors associated to it in a sample of male college students, taking into account genotype and viral load. Methods: From 2002 to 2003, male students from the Autonomous University of Morelos State completed a questionnaire and provided self-collected genital samples to detect and quantify HPV. We performed a bivariate and a multivariate logistic regression analysis to identify correlates associated with the infection and to assess the viral load as a function of the viral infecting type. The fragments of β-globin gene and L1 of HPV, were amplified, purified and cloned, to evaluate viral load. Results: Among 253 subjects, HPV prevalence was 19.4%, and HPV16 was the most common subtype. History of STIs (OR = 4.8; 95% CI 1.2–18.9), contraceptive pill use by female partner (OR = 2.6; 95% CI 1.1–6.3) and exchanging sex for money (OR = 4.9; 95% CI 1.2–20) were associated to the HPV infection. HPV16 viral load was 7.8 copies (HPV/beta-globin) compared to 0.9 copies for other HPV types. Discussion: HPV16 displayed the highest viral load, and it was the most prevalent. It was found that using contraceptive pills by female partners was associated with HPV infection. .

Genética de las poblaciones virales y transmisión del dengue / Population genetics of dengue virus and transmission of dengue fever

El comportamiento endémico de la fiebre por dengue en México durante los últimos cinco años ha generado gran preocupación en todos los sectores relacionados con la salud. Los esfuerzos para interrumpir la transmisión se han concentrado en el control vectorial; sin embargo, al margen de la efectividad de las intervenciones, resulta importante establecer con claridad cuáles son los elementos determinantes de la transmisión del dengue para establecer medidas de control y vigilancia eficaces. En cuanto a los determinantes moleculares de la transmisión, mucho se ha avanzado con el desarrollo de la genómica y la bioinformática. Esta revisión pretende ofrecer un panorama de los desarrollos más recientes en ese aspecto con un énfasis en la situación de México.

The endemic behavior of dengue fever in Mexico during the past five years is of major concern to every sector related with public health and the effort to control the transmission has been focused on vector control. However, regardless of the effectiveness of the intervention measures it is important to know which elements determine dengue transmission. With regard to the molecular basis for dengue transmission, a great deal of progress has been made due to the introduction of genomic and bioinformatic approaches. The goal of this review is to describe the most recent developments in this area with emphasis on the Mexican situation.

Prevalencia de anticuerpos neutralizantes contra los serotipos del virus dengue en universitarios de Tabasco, México / Prevalence of neutralizing antibodies to dengue virus serotypes in university students from Tabasco, Mexico

OBJETIVO: Determinar la seroprevalencia de anticuerpos neutralizantes de los serotipos del virus dengue en estudiantes universitarios de Tabasco, México, durante los meses de septiembre a noviembre del año 2005. MATERIAL Y MÉTODOS: Se determinó la presencia de IgG contra el virus en el suero de estudiantes que acudieron al centro clínico de la universidad; en los sueros positivos se determinaron los anticuerpos neutralizantes mediante el ensayo de reducción de placa lítica. RESULTADOS: La prevalencia de IgG contra el dengue fue de 9.1 por ciento; de esta proporción, los anticuerpos neutralizantes fueron DENV-1 (20 por ciento), DENV-2 (100 por ciento), DENV-3 (4 por ciento) y DENV-4 (68 por ciento). CONCLUSIONES: Este estudio muestra que el serotipo transmitido con mayor frecuencia en el estado de Tabasco es el DENV-2, aunque no ha sido el aislado con más frecuencia. La elevada prevalencia de anticuerpos neutralizantes contra el DENV-4, al parecer de reacción cruzada, podría explicar la baja circulación de este serotipo en Tabasco.

OBJECTIVE: Determine the seroprevalence of neutralizing antibodies to dengue virus in students from the state university of Tabasco, Mexico. MATERIAL AND METHODS: A transversal study was conducted of serum collected from students between September and November, 2005. The sera were screened for anti-dengue IgG and those that had evidence of dengue antibodies were analyzed by a plaque reduction neutralization test. RESULTS: Prevalence of anti-dengue IgG was 9.1 percent. The frequency of neutralizing antibodies was 100 percent for DENV-2, 68 percent for DENV-4, 20 percent for DENV-1, and 4 percent for DENV-3. CONCLUSIONS: We found that in this population, DENV-2 circulates more than DENV-3 despite the fact that DENV-3 is more frequently isolated. Unexpectedly, neutralizing antibodies against DENV-4 were frequently found even though this serotype is almost extinct; thus, it is probable that cross-immunity could suppress DEN-4 transmission, as has been suggested.

Phylogenetic analysis of the envelope protein (domain lll) of dengue 4 viruses

Objective. To evaluate the genetic variability of domain III of envelope (E) protein and to estimate phylogenetic relationships of dengue 4 (Den-4) viruses isolated in Mexico and from other endemic areas of the world. Material and Methods. A phylogenetic study of domain III of envelope (E) protein of Den-4 viruses was conducted in 1998 using virus strains from Mexico and other parts of the world, isolated in different years. Specific primers were used to amplify by RT-PCR the domain III and to obtain nucleotide sequence. Based on nucleotide and deduced aminoacid sequence, genetic variability was estimated and a phylogenetic tree was generated. To make an easy genetic analysis of domain III region, a Restriction Fragment Length Polymorphism (RFLP) assay was performed, using six restriction enzymes. Results. Study results demonstrate that nucleotide and aminoacid sequence analysis of domain III are similar to those reported from the complete E protein gene. Based on the RFLP analysis of domain III using the restriction enzymes Nla III, Dde I and Cfo I, Den-4 viruses included in this study were clustered into genotypes 1 and 2 previously reported. Conclusions. Study results suggest that domain III may be used as a genetic marker for phylogenetic and molecular epidemiology studies of dengue viruses.

Objetivo. Evaluar la variabilidad genética del dominio III de la proteína de envoltura (E) y estimar la relación filogenética de los virus dengue 4 (Den-4) aislados en México y en otras regiones endémicas del mundo. Material y métodos. En el presente trabajo reportamos un estudio filogenético del dominio III de la proteína de envoltura (E) que se realizó en 1998 con virus Den-4 aislados en distintos años en México y en otras partes del mundo. Se usaron oligonucleótidos específicos para amplificar por RT-PCR la región del dominio III y para obtener la secuencia de nucleótidos. Mediante el análisis de la secuencia de nucleótidos y de la secuencia deducida de aminoácidos se estimó la variabilidad genética y se generó un árbol filogenético. Para facilitar el análisis genético del dominio III se usó la técnica basada en el polimorfismo de fragmentos generados con enzimas de restricción (PFER) utilizando seis enzimas de restricción. Resultados. Los datos demuestran que la información del análisis de la secuencia de nucleótidos y de aminoácidos de la región del dominio III es similar a la del gene completo de la proteína E. El análisis de PFER con las enzimas de restricción Nla III, Dde I y Cfo I, mostró que los virus Den-4 incluidos en este estudio se agruparon en los genotipos 1 y 2 reportados previamente. Conclusiones. Los resultados sugieren que el dominio III se puede utilizar como un marcador para estudios filogenéticos y de epidemiología molecular del virus Den-4.

Dengue virus: detection and pathogeny

Sequences from a cDNA of dengue virus type 4 were cloned into transcription vectors. These sequences included the E, NS1, NS2A, NS2B, NS3 genes. RNA transcipts produced in vitro from these plasmids were used in hybridization assays to detect dengue viral sequences. With these RNA-probes we have been able to detect molecules of serotype-specific dengue 4 viral RNA. Moreover, the riboprobes detected viral sequences of other serotypes in the following order of sensitivity 4 > 2 > 3 > 1, and might be useful to differentiate serotypes

Synaptophysin and neurofilament expression in neurons infected with dengue virus

The expression of two genes encoding the neuronal specific proteins synaptophysin and high molecular weigh neurofilaments was investigated in primary cell cultures of embryonic mouse brain infected with dengue virus type 2, using immunocytochemistry and Western blot analysis with monoclonal antibodies. The viral infection leads to a 20-fold induction in the expression of the mentioned synaptogenesis-related proteins. These results suggest a correlation between virus infection and neuropathology of immature neurons in vivo