Adrian Alejandro Farias

Understanding mosquito (Diptera: Culicidae) feeding behaviour is essential for assessing arbovirus transmission risk. Culex mosquitoes are key vectors, yet their host‐feeding patterns in urban areas of South America remain understudied. This study examined the blood‐feeding patterns of four Culex species in Córdoba, Argentina, emphasizing overall trends, seasonality and host preferences. Mosquitoes were collected during spring, summer and autumn across four urban sites over a 2‐year period (2017–2018). Blood meals were identified through molecular analysis. Culex dolosus fed exclusively on birds, while Cx. interfor Dyar, Cx. saltanensis Dyar and Cx. quinquefasciatus Say fed on both birds and mammals. Culex quinquefasciatus accounted for most identified blood meals ( n = 219), with 83% derived from birds and 17% from mammals. The most frequently detected local avian hosts were Zenaida auriculata (24.5%) and Passer domesticus (10%), while the most common mammalian hosts were Canis lupus familiaris (14.5%) and Homo sapiens (13.6%). Bird‐derived blood meals predominated in all seasons. Forage ratio estimates indicated that Cx. quinquefasciatus exhibited a preference for P. domesticus , Agelaioides badius and C. lupus familiaris . These results highlight key vertebrate hosts potentially involved in local transmission cycles, with Z. auriculata and P. domesticus emerging as important nodes for arbovirus maintenance in urban Córdoba.

This study explores the potential spillback of dengue virus (DENV) from urban to wild environments through the detection of neutralizing antibodies against DENV in sylvatic populations of bats from the Argentinean Yungas. Sampling campaigns were conducted in the Yungas biogeographical region of northwest Argentina during April 2021 and 2022. Bat blood samples were collected and tested for neutralizing antibodies against DENV-1 using the Plaque-Reduction Neutralization Test (PRNT). DENV-1 antibodies were detected in 2.8% (4/143) of the bat samples, with positive samples found in four species: Sturnira lilium, S. erythromos, Artibeus planirostris, and Tadarida brasiliensis. All from sylvatic habitats. The presence of DENV-1 antibodies in sylvatic bats suggests potential exposure to the virus in wild areas, indicating a possible spillback of DENV in subtropical areas of Argentina. Further research is needed to understand the role of bats as reservoirs for DENV and their impact on the virus endemicity.

The genus Flavivirus comprises approximately 80 different viruses. Phylogenetic relationships among its members indicate a clear ecological separation between those viruses transmitted by mosquitoes, ticks, with no known vector, and insect-specific Flaviviruses. The diversity and phylogenetic relationships among insect-specific flaviviruses circulating in the central and northern regions of Argentina were studied by performing molecular detection and characterization of the NS5 protein gene in mosquitoes collected in Córdoba, Chaco and Tucumán provinces. Overall, 68 out of 1776 pools were positive. CxFV, KRV and CFAV circulate in the 3 studied provinces. Several mosquito species (Aedes aegypti, Culex bidens, Cx. dolosus, Cx. interfor, Cx. quinquefasciatus, Cx. saltanensis, Haemagogus spegazzini) were found infected. A wide circulation of CxFV was observed in the central-northern region of Argentina. CxFV strains detected in our study clustered with strains circulating in Santa Fe and Buenos Aires provinces (Argentina), and other countries such as Indonesia, Mexico, Uganda and Taiwan. The presence of these viruses in mosquitoes could play an important role from the public health perspective, because it has been shown that previous CxFV infection can increase or block the infection of the mosquito by other pathogenic flaviviruses.

In order to study the diversity and phylogenetic relationships among insect-specific flaviviruses circulating in the central and northern regions of Argentina we performed molecular detection and characterization of the NS5 protein gene in mosquitoes collected in Córdoba, Chaco and Tucumán provinces between 2001 and 2012, Sixty eight out of 1776 pools were positive. The KRV, CFA and CxFV viruses were detected by the generic PCR method, achieving the analysis of the existing phylogenetic relationships in the Flavivirus genus and the characterization of circulating CxFV in Argentina. It has also been possible to detect, for the first time, the CxFV virus in the mosquito species Haemagogus spegazzini.

Melatonin (MEL) has antioxidant properties and participates in osteogenic differentiation. In periodontitis, in which increased oxidative stress and bone resorption are involved, mesenchymal stem cells derived from the gingiva (GMSCs) combined with MEL could be relevant for osteogenic regeneration. In this study, we studied the antioxidant and differentiating effect of MEL on an in vitro system of GMSCs. Primary culture of GMSCs from Wistar rats was developed to evaluate differentiation into osteoblasts with an appropriate medium with or without MEL. Marker genes of mesenchymal stem cells by real time‐polymerase chain reaction, clonogenic capacity, and cell migration after wound assay were used to characterize GMSCs as mesenchymal stem cells. Alkaline phosphatase activity and the alizarin red technique were used to evaluate osteogenic activity and differentiation. MEL increased alkaline phosphatase activity and alizarin red values, promoting osteogenic differentiation. Besides this, MEL protected GMSCs in a model of cellular damage related to oxidative stress, returning viability to baseline. MEL was more effective in promoting and protecting GMSCs by the production of osteogenic cells when oxidative stress is present. This evidence supports the use of MEL as a novel bone‐regenerative therapy in periodontal diseases.

The knowledge about circulation of Human Enteroviruses (EVs) obtained through medical diagnosis in Argentina is scarce. Wastewater samples monthly collected in Córdoba, Argentina during 2011–2012, and then in 2017–2018 were retrospectively studied to assess the diversity of EVs in the community. Partial VP1 gene was amplified by PCR from wastewater concentrates, and amplicons were subject of next-generation sequencing and genetic analyses. There were 41 EVs detected, from which ~50% had not been previously reported in Argentina. Most of the characterized EVs (60%) were detected at both sampling periods, with similar values of intratype nucleotide diversity. Exceptions were enterovirus A71, coxsackievirus B4, echovirus 14, and echovirus 30, which diversified in 2017–2018. There was a predominance of types from EV-C in 2017–2018, evidencing a common circulation of these types throughout the year in the community. Interestingly, high genetic similarity was evidenced among environmental strains of echovirus 30 circulating in 2011–2012 and co-temporal isolates obtained from patients suffering aseptic meningitis in different locations of Argentina. This study provides an updated insight about EVs circulating in an important region of South America, and suggests a valuable role of wastewater-based epidemiology in predicting outbreaks before the onset of cases in the community.

Environmental surveillance is an effective approach to investigate the circulation of human enteroviruses (EVs) in the population. EVs excreted by patients who present diverse clinical syndromes can remain infectious in the environment for several weeks, and limited data on circulating environmental EVs are available. A 6-year (2009–2014) surveillance study was conducted to detect non-polio enteroviruses (NPEVs) in the urban sewage of Cordoba city, Argentina. Echovirus 6 (E-6) was the most prevalent (28%), followed by E-14 (17%), E-16 (14%), Coxsackievirus (CV) A9 (11%), E-20 (9%), and CVA24 (6%). Other minority serotypes (E-7, E-13, E-21, E-25, and CVB4) were found, which together represented 14% of the total. In the absence of a systematic EV disease surveillance system, the detection and characterization of sewage-borne NPEVs will help us better understand the changes in EV disease trends and the epidemic background of circulating EVs, which could help interpret the EV trends and warn of future outbreaks in this area.

Environmental surveillance is an effective approach to investigate the circulation of human enteroviruses in the population. Enteroviruses E14, CVA9, E-6, E16, E20, E25, E13, and CVA24 were detected in sewage and a watercourse in central Argentina. E14 was the most frequent serotype and was found for the first time in environmental samples in our region. Phylogenetic and coalescence analyses showed at least two recent introduction events.

The aim of this study was to analyze the prevalence of hepatitis C virus (HCV) genotypes in Cordoba province, Argentina, over a 12-year period and to study the changes at the molecular level. The HCV genotype was determined in 357 HCV-infected patients, and the phylogeny and demographic reconstruction for HCV-1 was assessed. A significant reduction in HCV-2 prevalence with respect to HCV-1 in Cordoba after 2003 was observed. These findings are consistent with the epidemiological changes observed in South America. Nevertheless, the consequences of these changes remain to be elucidated.

The purpose of this study was to update the epidemiological data on the prevalence of coinfection with hepatitis C virus (HCV) and HIV, and to identify whether specific clinical and epidemiological factors influenced the response of HIV-positive adults to highly active antiretroviral therapy (HAART). This retrospective observational cohort study of 238 HIV-infected patients evaluated the effect of different epidemiological and clinical parameters (including HCV coinfection) on therapy response among HIV-infected adults initiating HAART. Multiple logistic regression models were used to identify factors associated with therapy response and estimated risk coefficients. Seroprevalence of HCV infection in this population was 26 (62/238). We did not observe a significant association between immunological or virological response relating to patient gender or HAART regimen. However, this analysis showed that HCV serological status, age at HIV diagnosis, duration of treatment and WHO clinical stage of AIDS (200 CD4 cells/ml independently of viral load either or to100000 copies/ml), were significantly associated with immunological and virological responses to HAART. These results show further evidence that hepatitis C serostatus is associated with a reduced response to HAART.