Eficacia y seguridad de la vacuna contra el dengue / Efficacy and safety of dengue vaccine

El dengue es un problema creciente para la salud pública mundial. En Argentina, los casos se han ido incrementado en los últimos años. La vacuna Dengvaxia (CYD-TDV) fue aprobada por la Agencia Nacional de Medicamentos, Alimentos y Tecnología (ANMAT) en 2017, y actualmente está indicada para personas entre los 9 y 45 años de edad que residan enzonas endémicas. A partir de la consulta de una paciente sobre la posibilidad de vacunarse contra el dengue, la autora se plantea la pertinencia de su indicación, teniendo en cuenta la eficacia y seguridad de la vacuna. Luego de una búsqueda rápida se encontró evidencia que señala que la vacuna contra el dengue CYD-TDV mostró poca eficacia en comparación con otras vacunas disponibles en el mercado, siendo más segura y eficaz en personas que ya han sido infectadas anteriormente por el virus del dengue (sujetos seropositivos). En cambio, se observó un aumento del riesgo de dengue grave en los infectados por vez primera tras la vacunación (sujetos seronegativos). Se concluye que la estrategia recomendada consiste en vacunar únicamente a las personas que hayan tenido infección por dengue con anterioridad, consistiendo en una buena práctica la toma de decisiones compartidas con cada paciente. (AU)

Dengue is a growing problem for global public health. In Argentina, cases have been increasing in recent years. The Dengvaxia vaccine (CYD-TDV) was approved by the National Agency for Medicines, Food and Technology in 2017, and it is currently indicated for people between 9 and 45 years of age who reside in endemic areas. Based on the consultation of a patient about the possibility of being vaccinated against dengue, the author considers the relevance of its indication, taking into account the efficacy and safety of the vaccine. After a quick search, evidence was found that indicates that the CYD-TDV dengue vaccine showed little efficacy compared to other vaccines available on the market, being safer and more effective in people who have already been previously infected by the dengue virus (seropositive subjects). In contrast, an increased risk of severe dengue was observed in those infected for the first time after vaccination (seronegative subjects). It is concluded that the recommended strategy consists of vaccinating only people who have had dengue infection before, making shared decisions with each patient a good practice. (AU)

Phylogenetic analysis of Dengue-2 serotypes circulating in mangroves in Northern Cordoba, Colombia

Abstract INTRODUCTION: In this study, we aimed to identify DENV-2 subtypes in Aedes aegypti pools collected between 2011 and 2017 in a rural area of Northern Cordoba, Colombia ("La Balsa"). METHODS: RT-PCR was performed to analyze the capsid/pre-membrane region (C-PrM). Sequencing and phylogenetic bayesian inference using reference DENV-2 sequences were performed. RESULTS: Twelve pools that tested positive for DENV-2 were characterized based on the C-PrM region and grouped under the Asian/American clade. CONCLUSIONS: This study is the first to report the DENV-2 Asian-American subtype in a rural area of Cordoba region, which is associated with severe dengue and local epidemics.

Variantes en los genes TNFA , IL6 e IFNG asociadas con la gravedad del dengue en una muestra de población colombiana / Variants in the TNFA , IL6 and IFNG genes associated with dengue severity in a sample of Colombian population

Resumen Introducción. La composición genética del huésped determina, entre otros aspectos, el perfil clínico del dengue, lo cual se debería al efecto de variantes en los genes que codifican citocinas proinflamatorias. Objetivo. Evaluar la asociación entre las variantes de tres polimorfismos en los genes candidatos TNFA, IL6 e IFNG con la gravedad del dengue en una población colombiana. Materiales y métodos. Se evaluaron los polimorfismos rs1800750, rs2069843 y rs2069705 de los genes TNFA, IL6 e IFNG, respectivamente, en 226 pacientes con dengue. Los genotipos se tipificaron usando la reacción en cadena de la polimerasa (PCR) y los polimorfismos de la longitud de los fragmentos de restricción (Restriction Fragment Length Polymorphism, RFLP). Para determinar el riesgo de diferentes fenotipos del dengue, se compararon las frecuencias alélicas con la prueba de ji al cuadrado, y los genotipos y los haplotipos, con regresión logística. Por último, los análisis se ajustaron utilizando datos de autoidentificación o del componente genético ancestral. Resultados. El alelo A del rs2069843, ajustado por autoidentificación, se asoció con casos de dengue hemorrágico en afrocolombianos. En la muestra completa, dicho polimorfismo, ajustado por componente genético ancestral, fue reproducible. Además, hubo asociaciones significativas entre las combinaciones alélicas GGT y GAC de los rs1800750, rs2069843 y rs2069705 en pacientes con dengue hemorrágico, con ajuste por componente genético ancestral y sin él. Además, la combinación alélica AGC produjo 58,03 pg/ml más de interleucina 6 que la GGC, independientemente de los componentes genéticos europeo, amerindio y africano. Conclusión. Las variantes de los polimorfismos GGT y GAC de los rs1800750, rs2069843 y rs2069705 en los genes TNFA, IL6 e IFNG, respectivamente, se correlacionaron con la gravedad del dengue en esta muestra de población colombiana.

Abstract Introduction: The genetic makeup of the host contributes to the clinical profile of dengue. This could be due to the effect of variants in the genes encoding pro-inflammatory cytokines. Objective: To evaluate the association between the variants of three polymorphisms in TNFA, IL6 and IFNG candidate genes with dengue severity in a sample of Colombian population. Materials and methods: We evaluated the rs1800750, rs2069843, and rs2069705 polymorphisms in TNFA, IL6 and IFNG candidate genes, respectively, in 226 patients with dengue infection. The genotypes were typed using both polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). To determine the risk of different dengue phenotypes, we compared allele frequencies with chisquare and genotypes and haplotypes using logistic regression. Finally, these analyzes were adjusted with data from self-identification or the ancestral genetic component. Results: The A allele in the rs2069843 polymorphism, adjusted by self-identification, was associated with dengue hemorrhagic fever cases in Afro-Colombians. In the entire sample, this polymorphism, adjusted by the ancestral genetic component, was reproducible. In addition, there were significant associations between GGT and GAC allelic combinations of rs1800750, rs2069843, and rs2069705 in dengue hemorrhagic fever patients, with and without adjustment by ancestral genetic component. Additionally, the AGC allelic combination produced 58.03 pg/ml of interleukin-6 more than the GGC combination, regardless of European, Amerindian and African genetic components. Conclusions: The variants of GGT and GAC polymorphisms of rs1800750, rs2069843, and rs2069705 in the TNFA, IL6 and IFNG genes, respectively, were correlated with the susceptibility to dengue severity in a sample of Colombian population.

Detección del virus del dengue en larvas y pupas de Aedes aegypti recolectadas en áreas rurales del municipio de Anapoima, Cundinamarca, Colombia / Dengue virus detection in Aedes aegypti larvae and pupae collected in rural areas of Anapoima, Cundinamarca, Colombia

Resumen Introducción. La incidencia y la prevalencia del dengue en Cundinamarca son elevadas y, recientemente, se detectó Aedes aegypti en algunas áreas rurales del departamento. Objetivo. Evaluar la transmisión transovárica del virus del dengue en larvas y pupas recolectadas en áreas rurales del municipio de Anapoima. Materiales y métodos. Se recolectaron ejemplares vivos en 53 viviendas y se transportaron al laboratorio de Anapoima, donde se clasificaron, se agruparon y se congelaron. Llevadas a Bogotá, se las homogeneizó, se les extrajo el ARN con Trizol ® , se las sometió a una reacción en cadena de la polimerasa de transcripción inversa (Reverse Transcription Polymerase change reaction, RT-PCR) y a PCR convencional, y los productos amplificados se analizaron en geles de agarosa al 2 %. Resultados. En 54,7 % de las viviendas evaluadas se encontraron formas inmaduras del vector y el serotipo más frecuente fue el DENV-1. Sin embargo, en algunos pools se detectó la presencia simultánea de los serotipos DENV 1 y 2, DENV 1 y 3, y DENV 1 y 4, así como los serotipos DENV 1, 2 y 3. Conclusión. Los resultados confirmaron la transmisión vertical del virus de manera natural en el área rural del municipio, lo cual reafirma la capacidad vectorial de A. aegypti y explica, en parte, la persistencia del virus en la región y la posibilidad de que en la fase adulta el vector lo transmita sin haber consumido sangre infectada. Esta situación aumenta el riesgo de infección por el virus del dengue en Colombia y, por lo tanto, la necesidad de adelantar programas de prevención y control en todas las zonas con presencia del mosquito.

Abstract Introduction: There is a high incidence and prevalence of dengue in the department of Cundinamarca, and recently Aedes aegypti, the main vector of dengue virus (DENV), was detected in some of its rural areas. Objective: To evaluate viral transovarial transmission in larvae and pupae collected in rural areas of the municipality of Anapoima, Cundinamarca. Materials and methods: Live larvae and pupae were collected from 53 homes and later they were taken to the laboratory in Anapoima, where they were classified, pooled and frozen. In Bogotá, they were homogenized, RNA was extracted with Trizol™ , and RT-PCR and conventional PCR were performed. The amplified products were analyzed on 2% agarose gels. Results: In 54.7% of the houses we found A. aegypti in immature stages, and DENV-1 was the most frequent serotype. However, the simultaneous presence of DENV 1 and 2, DENV 1 and 3, DENV 1 and 4, and DENV 1, 2 and 3 serotypes was detected in some pools. Conclusion: The results confirmed the natural vertical transmission of the virus in the rural area under study. These findings confirmed the vector capacity of A. aegypti, and partly explains the persistence of the virus in the region and the possibility of transmission by the vector during adulthood without having ingested infected blood. This situation increases the risk of DENV infection in Colombia and the need for prevention and control programs in all areas where the mosquito is present.

Infección de Aedes albopictus (Skuse, 1894) con el genotipo asiático-americano del virus del dengue serotipo 2 en Medellín y su posible papel como vector del dengue en Colombia / Aedes albopictus (Skuse, 1894) infected with the American-Asian genotype of dengue type 2 virus in Medellín suggests its possible role as vector of dengue fever in Colombia

Resumen Introducción. Aedes aegypti y Ae. albopictus son reconocidos vectores de arbovirus como los del dengue, la fiebre amarilla, el chikungunya y el Zika, en regiones tropicales y subtropicales del mundo. En Colombia, la distribución geográfica de Ae. albopictus ha sufrido un incremento y hoy incluye ciudades como Cali y Medellín. Hasta ahora, sin embargo, no se ha recabado información concluyente sobre su infección viral y su capacidad de transmisión a los humanos. Objetivo. Determinar la infección natural por dengue en ejemplares de Ae. albopictus recolectados en un área urbana de Medellín. Materiales y métodos. Se recolectaron individuos de Ae. albopictus en el campus de la Universidad Nacional de Colombia, sede Medellín. Se confirmó su clasificación taxonómica mediante el análisis del gen citocromo oxidasa I (COI), y se extrajo el ARN total para la identificación del virus del dengue y de los respectivos serotipos. La presencia del genotipo DENV se infirió mediante el análisis del gen NS3. Resultados. El análisis del COI corroboró el estatus taxonómico de Ae. albopictus. Uno de los mosquitos procesados fue positivo para DENV-2 y el análisis del NS3 mostró una gran similitud con el genotipo asiático-americano. Conclusión. Se reporta la infección con DENV-2 en Ae. albopictus en Medellín, Colombia. La presencia del genotipo asiático-americano en una zona urbana sugiere su posible circulación entre humanos y en Ae. albopictus, lo cual alerta sobre su eventual papel en la transmisión del DENV-2, y sobre la necesidad de incluir esta especie en la vigilancia entomológica en Colombia.

Abstract Introduction: Aedes aegypti and Ae. albopictus are recognized vectors of dengue, yellow fever, chikungunya and Zika arboviruses in several countries worldwide. In Colombia, Ae. albopictus geographical distribution has increased to include highly populated cities such as Cali and Medellín. Although this species has been frequently found in urban and semi-urban zones in the country, its role as vector of the dengue fever is poorly known. Objective: To identify the presence of Ae. albopictus specimens naturally infected with dengue virus collected in Medellín. Materials and methods: Insects were collected in the Universidad Nacional de Colombia campus in Medellín. Individuals were classified as Ae. albopictus and confirmed by DNA barcode region analysis. Mosquitoes were processed for dengue virus identification, and a fragment of the NS3 gen was sequenced and compared with DENV-2 genotypes reported in the literature. Results: Sequence analysis of COI indicated Ae. albopictus individuals were similar to those recently reported in Colombia, and genetically close to those from other regions worldwide. Among the pools tested one was positive for DENV-2, and the NS3 analysis indicated it belonged to the Asian-American clade. Conclusion: We report the presence Ae. albopictus naturally infected with the Asian-American genotype of DENV-2 in Colombia. The presence of Ae. albopictus specimens carrying the most common genotype infecting humans in a highly populated city such as Medellín indicates its potential role as dengue vector in Colombia and highlights the relevance of including it in current vector surveillance strategies.

Subversion of immunoproteasome subunit expression in dengue virus serotype 2-infected HepG2 cells

Abstract: INTRODUCTION: Infection with all serotypes of dengue virus (DV) results in augmented antigen presentation by MHC class I molecules. However, the upregulation of immunoproteasome subunits only results from infection with two serotypes. This study aims to elucidate changes in the expression of immunoproteasome subunits resulting from infection with DV, particularly DV serotype 2 (DV2). METHODS: HepG2 cells were grown in various culture milieu. Total cellular RNA and proteins were extracted and quantified. RESULTS: Results demonstrated sequestration of immunoproteasome subunits LMP2 and LMP7 in DV2-infected cells. CONCLUSIONS: This study provides insights into the mechanisms underlying immune evasion by DV.

Mosquito-transmitted viruses - the great Brazilian challenge

ABSTRACT Arboviruses pose a serious threat to public health worldwide, overloading the healthcare system and causing economic losses. These viruses form a very diverse group, and in Brazil, arboviruses belonging to the families Flaviviridae and Togaviridae are predominant. Unfortunately, the number of arboviruses increases in proportion with factors such as deforestation, poor sanitation, climate changes, and introduction of new viruses like Chikungunya virus and Zika virus. In Brazil, dengue is endemic, along with the presence of other arboviruses. The situation is complicated by the scarcity of diagnostic infrastructure and the absence of approved vaccines for these diseases. Disease control, thus, relies solely on vector control. Therefore, enhanced clinical knowledge and improved general awareness about these arboviruses are indispensable to tackle diagnostic inadequacies.

Detection of all four dengue serotypes in Aedes aegypti female mosquitoes collected in a rural area in Colombia

The Aedes aegypti vector for dengue virus (DENV) has been reported in urban and periurban areas. The information about DENV circulation in mosquitoes in Colombian rural areas is limited, so we aimed to evaluate the presence of DENV in Ae. aegypti females caught in rural locations of two Colombian municipalities, Anapoima and La Mesa. Mosquitoes from 497 rural households in 44 different rural settlements were collected. Pools of about 20 Ae. aegypti females were processed for DENV serotype detection. DENV in mosquitoes was detected in 74% of the analysed settlements with a pool positivity rate of 62%. The estimated individual mosquito infection rate was 4.12% and the minimum infection rate was 33.3/1,000 mosquitoes. All four serotypes were detected; the most frequent being DENV-2 (50%) and DENV-1 (35%). Two-three serotypes were detected simultaneously in separate pools. This is the first report on the co-occurrence of natural DENV infection of mosquitoes in Colombian rural areas. The findings are important for understanding dengue transmission and planning control strategies. A potential latent virus reservoir in rural areas could spill over to urban areas during population movements. Detecting DENV in wild-caught adult mosquitoes should be included in the development of dengue epidemic forecasting models.

Primary dengue virus infections induce differential cytokine production in Mexican patients

Severe dengue pathogenesis is not fully understood, but high levels of proinflammatory cytokines have been associated with dengue disease severity. In this study, the cytokine levels in 171 sera from Mexican patients with primary dengue fever (DF) and dengue haemorrhagic fever (DHF) from dengue virus (DENV) 1 (n = 116) or 2 (n = 55) were compared. DF and DHF were defined according to the patient’s clinical condition, the primary infections as indicated by IgG enzymatic immunoassay negative results, and the infecting serotype as assessed by real-time reverse transcription-polymerase chain reaction. Samples were analysed for circulating levels of interleukin (IL)-12p70, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-6, and IL-8 using a commercial cytometric bead array. Significantly higher IFN-γ levels were found in patients with DHF than those with DF. However, significantly higher IL-12p70, TNF-α, and IL-6 levels were associated with DHF only in patients who were infected with DENV2 but not with DENV1. Moreover, patients with DF who were infected with DENV1 showed higher levels of IL-12p70, TNF-α, and IL-6 than patients with DHF early after-fever onset. The IL-8 levels were similar in all cases regardless of the clinical condition or infection serotype. These results suggest that the association between high proinflammatory cytokine levels and dengue disease severity does not always stand, and it once again highlights the complex nature of DHF pathogenesis.

Phylogenetic analysis of Dengue virus 1 isolated from South Minas Gerais, Brazil

Abstract Dengue is a major worldwide public health problem, especially in the tropical and subtropical regions of the world. Primary infection with a single Dengue virus serotype causes a mild, self-limiting febrile illness called dengue fever. However, a subset of patients who experience secondary infection with a different serotype can progress to a more severe form of the disease, called dengue hemorrhagic fever. The four Dengue virus serotypes (1–4) are antigenically and genetically distinct and each serotype is composed of multiple genotypes. In this study we isolated one Dengue virus 1 serotype, named BR/Alfenas/2012, from a patient with dengue hemorrhagic fever in Alfenas, South Minas Gerais, Brazil and molecular identification was performed based on the analysis of NS5 gene. Swiss mice were infected with this isolate to verify its potential to induce histopathological alterations characteristic of dengue. Liver histopathological analysis of infected animals showed the presence of inflammatory infiltrates, hepatic steatosis, as well as edema, hemorrhage and necrosis focal points. Phylogenetic and evolutionary analyses based on the envelope gene provided evidence that the isolate BR/Alfenas/2012 belongs to genotype V, lineage I and it is probably derived from isolates of Rio de Janeiro, Brazil. The isolate BR/Alfenas/2012 showed two unique amino acids substitutions (SER222THRE and PHE306SER) when compared to other Brazilian isolates from the same genotype/lineage. Molecular models were generated for the envelope protein indicating that the amino acid alteration PHE 306 SER could contribute to a different folding in this region located within the domain III. Further genetic and animal model studies using BR/Alfenas/2012 and other isolates belonging to the same lineage/genotype could help determine the relation of these genetic alterations and dengue hemorrhagic fever in a susceptible population.

Microevolutionary trends of dengue virus-3 in Kerala, India.

Envelope gene is of great evolutionary significance and had been targeted as the vaccine candidate for dengue virus. We analyzed partial sequences of this gene to understand its genetic variability among viral isolates from Kerala state, India, if any. The current study focused on the evolutionary trends of this phylogenetically important gene among DENV-3 isolates through 2008 to 2010 outbreaks. The results gave an insight into the microevolutionary trends of the dengue viral genome. A unique mutation was recorded in the Domain II of the Envelope gene (EDII) of the viral genome at the amino acid position 219 (A219T). The evolutionary implication of this non-synonymous mutation near the EDI/EDII hinge remains to be explored. The study also provided knowledge on the genetic ancestral history of the viral isolates. Two variants of different phylogenetic origin were recorded in Kerala State. The findings in the study have significant implications on the development of dengue vaccines based on the Envelope gene of the virus.

Perfil dos sinais e sintomas mais prevalentes na epidemia de dengue pelo sorotipo 4 em Campos dos Goytacazes (RJ) / Profile of signs and symptoms more prevalent in the epidemic of dengue serotype 4 in Campos dos Goytacazes (RJ)

JUSTIFICATIVA E OBJETIVO: O quadro clínico da dengue é composto por sinais e sintomas variáveis, dependendo de di- versos fatores, como a existência de quatro sorotipos virais. O objetivo deste estudo foi identificar os sinais e sintomas mais prevalentes durante a epidemia de dengue pelo sorotipo 4. MÉ- TODOS: Estudo observacional realizado por meio de análise de 600 prontuários de pacientes atendidos no Centro de Referência da Dengue em Campos (RJ), no período de janeiro a abril de 2013. Foram selecionados prontuários de pacientes de ambos os sexos, faixa etária superior a 13 anos de idade e com sorologia antidengue IgM reagente. As variáveis analisadas foram: faixa etária, sexo, sinais e sintomas apresentados no primeiro atendi- mento ambulatorial. RESULTADOS: Na amostra analisada, a faixa etária predominante foi de 41 a 60 anos (37,5%), seguida pela de 21 a 40 anos (36,7%). Pertenciam ao sexo feminino 61,5% dos pacientes. Dentre os sinais e sintomas, destacam-se febre (89,2%), cefaleia (82,2%), mialgia (79,8%) e dor retro- or bitária (60,5%). Outros sinais e sintomas foram observados em menor frequência: dor em membros inferiores (11,3%), dor lombar (10,2%), sinais hemorrágicos (6,5%) e parestesia em membros inferiores (1,5%). CONCLUSÕES: Sintomas como febre, cefaleia, mialgia e dor retro-orbitária permaneceram entre as manifestações mais comuns da doença. Sintomas incomuns estiveram presentes, mesmo que em menor proporção. Sinais hemorrágicos intensos e de insuficiência circulatória foram pou- co observados, mostrando o caráter mais brando da infecção por esse sorotipo viral.(AU)

BACKGROUND AND OBJECTIVE: The clinical manifestations of dengue is composed of signs and symptoms varying depending on several factors, such as the existence of four serotypes. The objective of this study was to identify the signs and symptoms more prevalent during the epidemic of dengue serotype 4. METHODS: This was an observational study through analysis of medical records of 600 patients seen at the Reference Center Dengue in Campos (RJ), Brazil, in the period from January to April 2013. Records of patients of both sexes, age greater than 13 years and with serology antidengue IgM reagent were selected. The variables analyzed were age, sex, signs and symptoms presented in the first outpatient care. RESULTS: In the sample analyzed, the predominant age group was 41-60 years (37.5%), followed by 21-40 years (36.7%); 61.5% were female. Fever (89.2%), headache (82.2%), myalgia (79.8%) and retro-orbital pain (60.5%) were the main signs and symptoms. Other signs and symptoms were observed less frequently: pain in the lower limbs (11,3 %), low back pain (10,2 %), signs bleeding (6,5 %) and paresthesia in the lower limbs (1,5 %). CONCLUSION: Symptoms such as fever, headache, myalgia and retro-orbital pain remained among the most common manifestations of the disease. Unusual symptoms were present, even in a smaller proportion. Intense bleeding and signs of circulatory failure were little observed, showing the softer character of infection by this serotype.(AU)

Compromiso gastrointestinal agudo en pacientes con dengue por serotipo 4: Comunicación de un caso y revisión de la literatura / Acute gastrointestinal involvement in dengue disease by serotype 4: a case report and literature review

Dengue fever is the world's most important arboviral disease, presenting a wide clinical spectrum. We report for the first time in Peru, a case caused by dengue virus serotype 4 with significant gastrointestinal involvement (acute acalculous cholecystitis and acute hepatitis). In addition we carried out a review of the literature atypical presentation illustrating the importance of the characteristics of abdominal pain (right upper quadrant); presence of Murphy's sign, ultrasound, and liver enzymes levels, for appropriate diagnosis and clinical management.

El dengue es la arbovirosis más importante del mundo y causa un amplio espectro clínico. Presentamos el primer caso de dengue causado por el serotipo 4 (DENV-4) en Perú con compromiso gastrointestinal (colecistitis aguda alitiásica y hepatitis aguda moderada). Se presenta una revisión de la literatura médica sobre este tipo de presentación, enfatizando la importancia y características del dolor abdominal (hipocondrio derecho), el signo de Murphy, los hallazgos ultrasonográficos y la medición de las enzimas hepáticas para establecer el diagnóstico y manejo adecuado.

Virus del dengue de serotipo 1 (DENV-1) de Colombia: su contribución a la presentación del dengue en el departamento de Santander / Dengue virus serotype 1 (DENV-1) from Colombia: its contribution to dengue occurrence in Santander

Introducción. Los cuatro serotipos del virus del dengue circularon en el departamento de Santander entre 1998 y 2008. No existe información sobre el papel del serotipo 1 (DENV-1) en la epidemiología de la enfermedad. Objetivo. Analizar la relación entre el cambio de predominancia del (DENV-1) con su diversificación genética, predominancia de los otros serotipos y presentación del dengue grave. Materiales y métodos. La diversificación genética se estudió por análisis filogenético usando la secuencia del gen E de 12 cepas del virus. Para el análisis se utilizaron datos sobre predominancia de los serotipos obtenidos en estudios previos y datos oficiales de incidencia del dengue. Resultados. Los virus seleccionados se agruparon en el genotipo V junto a (DENV-1) de países de Latinoamérica y se evidenció segregación en cuatro linajes. Los cambios en la predominancia del virus coincidieron con el reemplazo de linaje y esto, a su vez, con incremento en la prevalencia de DENV-2 y DENV-3, e incremento del dengue grave. Conclusión. La diversificación genética podría contribuir a cambios de predominancia de (DENV-1), y la relación del virus con el DENV-2 y DENV-3 en situaciones que favorecen la presentación de casos graves. Se necesitan más estudios para precisar el papel de los serotipos en la epidemiología del dengue.

Introduction: Between 1998 and 2008 all dengue virus serotypes circulated in the Departamento de Santander, an endemic region in northeastern Colombia. No information is available as to the role of serotype 1 (DENV-1) with respect to epidemiology of dengue. Objective: To analyze the relationship between changes in DENV-1 predominance with respect to genetic diversity, prevalence of others serotypes and occurrence of severe dengue. Methods: Virus genetic diversity was studied by phylogenetic analysis comparing E gene sequences from 12 viral strains. Data about serotypes predominance obtained in previous studies and official data about dengue incidence were used for analysis. Results: Selected viruses grouped into genotype V together DENV-1 from Latin America countries, and segregation in four lineages was evidenced. Changes in virus predominance coincided with replacement of lineage, increase in prevalence of DENV-2 and DENV-3 and increase of severe dengue. Conclusion: Genetic divergence could have contributed to changes in DENV-1 predominance. The relationship of the virus with DENV-2 and DENV-3 could create scenarios that promote occurrence of severe cases. More studies are required to ascertain the precise role of serotypes in the epidemiology of dengue.

Analysis of real time PCR amplification efficiencies from three genomic region of dengue virus / Análisis de las eficiencias de amplificación por PCR en tiempo real de tres regiones genómicas del virus dengue

Early diagnosis of dengue virus (DENV) infection represents a key factor in preventing clinical complications attributed to the disease. The aim of this study was to evaluate the amplification efficiencies of an in-house quantitative real time-PCR (qPCR) assay of DENV, using the non-structural conserved genomic region protein-5 (NS5) versus two genomic regions usually employed for virus detection, the capsid/pre-membrane region (C-prM) and the 3’-noncoding region (3’NC). One-hundred sixty seven acute phase serum samples from febrile patients were used for validation purposes. Results showed that the three genomic regions had similar amplification profiles and correlation coefficients (0.987-0.999). When isolated viruses were used, the NS5 region had the highest qPCR efficiencies for the four serotypes (98-100%). Amplification from acute serum samples showed that 41.1% (67/167) were positive for the universal assay by at least two of the selected genomic regions. The agreement rates between NS5/C-prM and NS5/3’NC regions were 56.7% and 97%, respectively. Amplification concordance values between C-prM/NS5 and NS5/3’NC regions showed a weak (k= 0.109; CI 95%) and a moderate (k= 0.489; CI 95%) efficiencies in amplification, respectively. Serotyping assay using a singleplex NS5-TaqMan® format was much more sensitive than the C-prM/SYBR Green® I protocol (76%). External evaluation showed a high sensitivity (100%), specificity (78%) and high agreement between the assays. According to the results, the NS5 genomic region provides the best genomic region for optimal detection and typification of DENV in clinical samples.

El diagnóstico precoz de la infección por el virus dengue (DENV) constituye un elemento clave para la prevención de las complicaciones clínicas propias de la enfermedad. El objetivo del estudio fue evaluar la detección de DENV mediante un ensayo cuantitativo de PCR-tiempo real (qPCR), desarrollado localmente, utilizando la región no-estructural-5 (NS5), versus dos regiones tradicionalmente empleadas para la detección del virus, la región cápside/pre-membrana (C-prM), y la región noncodificante-3’ (3’NC). Se recolectaron 167 muestras de suero de pacientes en fase aguda de la enfermedad. Las tres regiones génicas tuvieron perfiles de amplificación/coeficientes de correlación similares (0,987-0,999). Sin embargo, la región NS5 tuvo la eficiencia de amplificación más elevada para los cuatro serotipos (98-100%). Durante el proceso de validación, 41,1% (67/167) de las muestras de suero resultaron positivas para DENV al menos por dos de las regiones genómicas empleadas. Los valores de concordancia entre las regiones NS5/C-prM y NS5/3’NC fueron de 56,7% y 97%, respectivamente. La concordancia fue débil entre las regiones NS5/C-prM (k= 0,109; CI 95%), sin embargo, fue moderada entre las regiones NS5/3’NC (k= 0,489; CI 95%). El ensayo de tipificación uniplex en formato NS5/TaqMan® mostró alta sensibilidad (100%) que el protocolo C-prM/SYBRGreen®-I (76%). La validación externa del ensayo mostró una alta sensibilidad (100%), especificidad (78%) y acuerdo alto entre los ensayos utilizados. De acuerdo a los resultados obtenidos, la región NS5 ofrece la mayor opción para la detección y serotipificación del DENV en muestras clínicas.

Episode of coexisting infections with multiple dengue virus serotypes in central Karnataka, India

The co-circulation of multiple dengue virus serotypes has been reported in many parts of the world, including India; however, concurrent infection with more than one serotype of dengue virus in the same individual is rarely documented. An outbreak of dengue hemorrhagic fever/dengue shock syndrome [DHF/DSS] occurred in and around Davangere, Karnataka, from June 2011-March 2012. This is the first report from India with a high percentage of concurrent infections with different dengue virus serotypes circulating during one outbreak. Acute phase sera from patients were tested for the presence of dengue virus RNA by RT-PCR. Of the 72 samples tested for dengue virus RNA, 42 [58.3%] were positive. All four dengue virus serotypes were found to be co-circulating in this outbreak, and DENV-2 was the predominant serotype. In addition, concurrent infection with more than one dengue virus serotype was identified in 18 [42.9%] dengue virus-positive samples. Our study showed that serotype DEN-2 was dominant in the positive dengue virus-infected samples; the other serotype present was DEN-3. This is the first report of concurrent infections with different dengue virus serotypes in this part of the world