Epidemiological surveillance of chikungunya fever in Mexico since its introduction in 2014-2016 and identification of circulating genotypes.

In 2014, the chikungunya virus (CHIKV) was detected for the first time in Mexico, the identified strain was the one corresponding to the Asian genotype which was phylogenetically grouped with the strains that circulated in the British Virgin Islands outbreak and was later classified with lineages of Caribbean strains. In three years, 13,569 cases of chikungunya were registered in Mexico. Although the transmission and spread of the virus are now considered a moderate risk, the danger that the virus reemerges is not ruled out due to the infestation of Aedes mosquitoes. In this study, we reviewed the chikungunya fever (CHIKF) cases reported between 2014 and 2016 to reanalyze the data. Seventeen cases were selected from different states where the circulation of the virus had been reported. Statistical data were analyzed and a retrospective analysis was carried out. Nucleic acid sequences were determined of these 17 samples. 2015 was the year with the highest number of cases (92.8%) and they were detected in 28 states of the country. There is a predominance of females, and the most affected age group was between 25 and 44 years. In 2016, CHIKV genotypes were not known, in this study the presence of the Asian genotype of Caribbean lineage was confirmed. The presence of the West African and ECSA genotypes was phylogenetically ruled out. The sequences obtained were deposited in GeneBank.

Genotypic variability analysis of DENV-1 in Mexico reveals the presence of a novel Mexican lineage.

Here, we report for the first time the circulation of dengue virus type 1 (DENV-1) belonging to the lineage IV of genotype V (African American genotype) based on phylogenetic analysis of nucleotide sequences from 10 DENV-1-positive samples obtained in Mexico between 2012 and 2014. Our data revealed that the lineages III and IV of DENV-1 genotype V were found circulating during the same period, probably explaining the rise in the number of cases of severe dengue during that period.

Evidence of the presence of the Zika virus in Mexico since early 2015.

To assess the possible circulation of Zika virus (ZIKV) prior to the first documented case in Mexico, we reanalyzed the stored samples from the states of Veracruz and Yucatán, which were originally collected to test for dengue (DENV) and chikungunya (CHIKV) but were negative for these viruses despite the symptomatology. The samples were originally collected between the 30 and 46 epidemiological weeks (EW) when the ZIKV was not yet declared as a Public Health Emergency of International Concern (PHEIC). From the total 4016 negative samples, a total of one hundred samples, 50 from Veracruz (CHIK- DENV-) and 50 from Yucatán (4 CHIK- DENV- and 46 CHIK- or DENV-), were tested for Zika virus by using RT-PCR. Results showed that in Veracruz and Yucatán, 20 % (10/50) and 70 % (35/50) were, respectively, ZIKV positive, indicating unequivocally the presence of ZIKV at least since July 2015. We also tested non-confirmed suspect measles cases from early 2015 for ZIKV by RT-PCR. Remarkably in 11 Mexican states, 86 % (18/21) were positive with the earlier symptoms onset as early as May 2015. Finally, RT-PCR analyses on RNA extracted from Aedes aegypti mosquitoes captured from January to March 2015 showed the presence of ZIKV, strongly suggesting that the vector was already carrying the virus at the start of 2015.

Identification of Asian genotype of chikungunya virus isolated in Mexico.

We identified 25 autochthonous chikungunya virus cases in Mexico, initially detected by RT-PCR targeting the E1 gene and propagated in C6/36 Aedes albopictus cells, in 2014. To determine the type of virus found, in a previous report, the genomes of 2 CHIKV strains were fully sequenced. Genome sequence analysis revealed that these isolates from Mexico belonged to the Asian genotype, and a phylogenetic association with the circulating strain in the British Virgin Islands was also established in the same year. This was further supported by changes in specific amino acids, E2-V368A and 6K-L20M. For these reasons, it can be inferred that the route of virus entry to Mexico was held across the countries in the Caribbean and Central America. The presence of E1-A226V mutation associated with more efficient replication in the salivary gland of the A. albopictus mosquito was not observed. Interestingly, a newly acquired NSP4-S399C mutation was observed; however, the significance of changes in amino acid found in non-structural proteins in autochthonous strains remains to be elucidated.

Chikungunya Virus, Metabolism, and Circadian Rhythmicity Interplay in Phagocytic Cells.

Chikungunya virus (CHIKV) is transmitted to humans by mosquitoes of the genus Aedes, causing the chikungunya fever disease, associated with inflammation and severe articular incapacitating pain. There has been a worldwide reemergence of chikungunya and the number of cases increased to 271,006 in 2022 in the Americas alone. The replication of CHIKV takes place in several cell types, including phagocytic cells. Monocytes and macrophages are susceptible to infection by CHIKV; at the same time, they provide protection as components of the innate immune system. However, in host-pathogen interactions, CHIKV might have the ability to alter the function of immune cells, partly by rewiring the tricarboxylic acid cycle. Some viral evasion mechanisms depend on the metabolic reprogramming of immune cells, and the cell metabolism is intertwined with circadian rhythmicity; thus, a circadian immunovirometabolism axis may influence viral pathogenicity. Therefore, analyzing the interplay between viral infection, circadian rhythmicity, and cellular metabolic reprogramming in human macrophages could shed some light on the new field of immunovirometabolism and eventually contribute to the development of novel drugs and therapeutic approaches based on circadian rhythmicity and metabolic reprogramming.

Specific detection of naturally occurring hepatitis C virus mutants with resistance to telaprevir and boceprevir (protease inhibitors) among treatment-naïve infected individuals.

The use of telaprevir and boceprevir, both protease inhibitors (PI), as part of the specifically targeted antiviral therapy for hepatitis C (STAT-C) has significantly improved sustained virologic response (SVR) rates. However, different clinical studies have also identified several mutations associated with viral resistance to both PIs. In the absence of selective pressure, drug-resistant hepatitis C virus (HCV) mutants are generally present at low frequency, making mutation detection challenging. Here, we describe a mismatch amplification mutation assay (MAMA) PCR method for the specific detection of naturally occurring drug-resistant HCV mutants. MAMA PCR successfully identified the corresponding HCV variants, while conventional methods such as direct sequencing, endpoint limiting dilution (EPLD), and bacterial cloning were not sensitive enough to detect circulating drug-resistant mutants in clinical specimens. Ultradeep pyrosequencing was used to confirm the presence of the corresponding HCV mutants. In treatment-naïve patients, the frequency of all resistant variants was below 1%. Deep amplicon sequencing allowed a detailed analysis of the structure of the viral population among these patients, showing that the evolution of the NS3 is limited to a rather small sequence space. Monitoring of HCV drug resistance before and during treatment is likely to provide important information for management of patients undergoing anti-HCV therapy.

Identification of hepatitis C virus transmission using a next-generation sequencing approach.

Here, we describe a transmission event of hepatitis C virus (HCV) among injection drug users. Next-generation sequencing (NGS) was used to assess the intrahost viral genetic variation. Deep amplicon sequencing of HCV hypervariable region 1 allowed for a detailed analysis of the structure of the viral population. Establishment of the genetic relatedness between cases was accomplished by phylogenetic analysis. NGS is a powerful tool with applications in molecular epidemiology studies and outbreak investigations.

Molecular epidemiology of autochthonous dengue virus strains circulating in Mexico.

Dengue virus (DENV) is the most important arthropod-borne viral infection in humans. Here, the genetic relatedness among autochthonous DENV Mexican isolates was assessed. Phylogenetic and median-joining network analyses showed that viral strains recovered from different geographic locations are genetically related and relatively homogeneous, exhibiting limited nucleotide diversity.

Is ultra-violet radiation the main force shaping molecular evolution of varicella-zoster virus?

BACKGROUND: Varicella (chickenpox) exhibits a characteristic epidemiological pattern which is associated with climate. In general, primary infections in tropical regions are comparatively less frequent among children than in temperate regions. This peculiarity regarding varicella-zoster virus (VZV) infection among certain age groups in tropical regions results in increased susceptibility during adulthood in these regions. Moreover, this disease shows a cyclic behavior in which the number of cases increases significantly during winter and spring. This observation further supports the participation of environmental factors in global epidemiology of chickenpox. However, the underlying mechanisms responsible for this distinctive disease behavior are not understood completely. In a recent publication, Philip S. Rice has put forward an interesting hypothesis suggesting that ultra-violet (UV) radiation is the major environmental factor driving the molecular evolution of VZV. DISCUSSION: While we welcomed the attempt to explain the mechanisms controlling VZV transmission and distribution, we argue that Rice's hypothesis takes lightly the circulation of the so called "temperate VZV genotypes" in tropical regions and, to certain degree, overlooks the predominance of such lineages in certain non-temperate areas. Here, we further discuss and present new information about the overwhelming dominance of temperate VZV genotypes in Mexico regardless of geographical location and climate. SUMMARY: UV radiation does not satisfactorily explain the distribution of VZV genotypes in different tropical and temperate regions of Mexico. Additionally, the cyclic behavior of varicella does not shown significant differences between regions with different climates in the country. More studies should be conducted to identify the factors directly involved in viral spreading. A better understanding of the modes of transmissions exploited by VZV and their effect on viral fitness is likely to facilitate the implementation of preventive measures for disease control.

Surveillance for Zika in Mexico: naturally infected mosquitoes in urban and semi-urban areas.

Zika cases have been reported in 29 out of the 32 states of Mexico. Information regarding which mosquito species might be driving Zika virus transmission/maintenance in nature must be regularly updated. From January 2017 to November 2018, mosquitoes were collected indoors and outdoors using the CDC backpack aspirator in urban and semi-urban areas with evidence of mosquito-borne disease transmission. 3873 mosquito pools were tested for Zika infection using the CDC Trioplex real-time RT-PCR. For each collected specie, maximum likelihood estimator of infection rate (MLE) was estimated. Results showed 492 mosquito pools positive for Zika virus RNA. The majority of the positive pools were Aedes (Stegomyia) aegypti (Linnaeus) (54.6%, MLE = 19) (males and females) and Culex (Culex) quinquefasciatus (Say) (19.5%, MLE = 16.8). For the first time, ZIKV infection was detected in Ae. (Georgecraigius) epactius (Dyar and Knab) (MLE = 17.1), Cx. (Melanoconion) erraticus (Dyar and Knab) (MLE = non-estimable), Culiseta (Culiseta) inornata (Williston) (MLE = non estimable), and Cs (Cs.) particeps (Adams) (MLE = 369.5). Other detected species were: Ae. (Stg.) albopictus (Skuse) (MLE = 90.5), Cx. (Cx.) coronator s.l. (Dyar and Knab) (MLE = 102.8) and Cx. (Cx.) tarsalis (Coquillett) (MLE = 117.2). However, our results do not allow for the incrimination of these species as vectors of ZIKV. Routine surveillance should start to consider other mosquito species across the taxonomic spectrum of the Culicidae.

Detection of Zika virus in Aedes mosquitoes from Mexico.

Background: We report on the results of an entomovirological surveillance system of Aedes populations performed by the Ministry of Health of the central state of San Luis Potosí, Mexico. Methods: Indoor adult Aedes aegypti and Aedes albopictus pools collected at San Martín, Tamazunchale, Ciudad Valles, Metlapa, Ebano, Tamuin and Axtla during the dry season of 2016 were examined for the presence of dengue (DENV), chikungunya (CHIKV) and Zika (ZIKV) viruses using real-time PCR. Results: Both Ae. aegypti and Ae. albopictus were found to be infected with ZIKV in the absence of confirmed symptomatic human cases. Conclusions: The entomovirological surveillance system analysed here identified both Ae. aegypti and Ae. albopictus infected with ZIKV which triggered an immediate aggressive vector control campaign.

Complete Genome Sequence of Zika Virus Isolated in Mexico, 2016.

Zika virus belongs to the genus Flavivirus, and its spread remains an international public health emergency. In this report, we describe the obtainment and molecular characterization of a complete viral genome through the direct metagenomic analysis from saliva from an autochthonous transmission case in Mexico.

Complete genome sequences of chikungunya virus strains isolated in Mexico: first detection of imported and autochthonous cases.

The mosquito-borne chikungunya virus, an alphavirus of the Togaviridae family, is responsible for acute polyarthralgia epidemics. Here, we report the complete genome sequences of two chikungunya virus strains, InDRE04 and InDRE51, identified in the Mexican states of Jalisco and Chiapas in 2014. Phylogenetic analysis showed that both strains belong to the Asian genotype.

Serotipos de dengue en México durante 2009 y 2010 / Dengue serotypes in México during 2009-2010

Introducción. El dengue en México es un problema prioritario de salud pública. Desde el 2008 el Departamento para la Vigilancia Epidemiológica y Virológica del InDRE implementó un nuevo algoritmo de diagnóstico del dengue, que utiliza la Red de Laboratorios Estatales de Salud Pública, para favorecer la representatividad geográfica, la oportunidad, la sensibilidad y la especificidad de la información que se obtiene. Métodos. La identificación de serotipos se realizó a partir de muestras positivas a la proteína NS1 por ensayo inmunoenzimático (ELISA). Las técnicas que se utilizaron fueron: aislamiento viral, PCR punto final y, desde 2009, RT-PCR en tiempo real (qRT-PCR). Resultados. En 2009 se analizaron 6,336 muestras; en 2,944 de éstas (46.6%) se identificó el serotipo DENV-1 que predominó sobre el serotipo DENV-2; el serotipo DENV-3 sólo se identificó en dos casos en Guerrero y el serotipo DENV-4 en un caso en Chiapas. En 2010 se analizaron 2,013 muestras. Se identificó algún serotipo en 1,607 muestras (79.88%) y, nuevamente, el serotipo DENV-1 predominó en todo el país. En Chiapas se identificaron los serotipos DENV-1, 2 y 4 y en Jalisco los serotipos DENV-1 y 3. Además, se identificó la circulación del serotipo DENV-3 en Guerrero y apareció el serotipo DENV-4 en San Luis Potosí. Conclusiones. Por la selección de muestras para vigilancia virológica de dengue mediante la positividad a la proteína NS1 y por la introducción de la técnica de qRT-PCR se optimizó la identificación de serotipos circulantes. La alta endemia, los brotes en nuevas regiones, el predominio del serotipo DENV-1 por varios años y la introducción lenta de otros serotipos, principalmente DENV-3, pueden favorecer la aparición de formas clínicas graves de dengue. La vigilancia epidemiológica inteligente del dengue brindará información para un mejor entendimiento de la enfermedad y promoverá acciones para su control y prevención.

Background. Dengue is a public health priority in Mexico. Since 2008, the dengue diagnostic algorithm for epidemiological and virological surveillance has been improved at InDRE and the public health laboratory network (RLESP) to optimize geographic representation, opportunity, sensitivity and specificity of the produced information. Methods. Dengue serotype identification is based on ELISA NS1 positive samples. Methods used are viral isolation, endpoint PCR and, since August 2009, real-time PCR (qRT-PCR). Results. In 2009, 6,336 serum samples were analyzed and 2,944 (46.6%) were positive for serotype identification. DENV-1 was detected in greater proportion followed by DENV-2, and DENV-3 4 was only identified in two cases in Guerrero and DENV-4 in one case in Chiapas. In 2010, 2,013 serum samples were analyzed and 1,607 (78.8%) were positive for serotype identification. DENV-1 was predominant throughout the country. In Chiapas, DENV-1, 2 and 4 were identified and in Jalisco DENV-1 and 3. DENV-3 was identified in Guerrero again and DENV-4 was detected in San Luis Potosí. Conclusions. The selection samples through NS1 positive samples and the introduction of qRT-PCR optimized serotype identification. Hyperendemicity, outbreaks in new geographic areas, the predominant circulation of DENV-1 for several years and the slow reintroduction of the other serotypes, mainly DENV-3, could increase clinical cases of severe dengue. An ¡intelligentí epidemiological surveillance program would offer information for a better understanding of the disease and promote action for its control and prevention.