Protocol to evaluate the antiviral effect of FDA-approved drugs against dengue virus in Huh7 cells and AG129 mice

Finding an effective therapy against diseases caused by flaviviruses remains a challenge. Here, we present a protocol to test Food and Drug Administration-approved drugs that inhibit host nuclear protein import, promoting a reduction of dengue infection. We describe steps for analyzing the drug effect on nuclear import inhibition of cellular and viral proteins by confocal microscopy or western blotting. We then describe procedures for measuring the antiviral drug effects on virus-infected cells by flow cytometry and testing drug efficacy in dengue-infected AG129 mice by survival assays. For complete details on the use and execution of this protocol, please refer to Palacios-Rápalo et al.1.

A Dual Pharmacological Strategy against COVID-19: The Therapeutic Potential of Metformin and Atorvastatin

Metformin (MET) and atorvastatin (ATO) are promising treatments for COVID-19. This review explores the potential of MET and ATO, commonly prescribed for diabetes and dyslipidemia, respectively, as versatile medicines against SARS-CoV-2. Due to their immunomodulatory and antiviral capabilities, as well as their cost-effectiveness and ubiquitous availability, they are highly suitable options for treating the virus. MET's effect extends beyond managing blood sugar, impacting pathways that can potentially decrease the severity and fatality rates linked with COVID-19. It can partially block mitochondrial complex I and stimulate AMPK, which indicates that it can be used more widely in managing viral infections. ATO, however, impacts cholesterol metabolism, a crucial element of the viral replicative cycle, and demonstrates anti-inflammatory characteristics that could modulate intense immune reactions in individuals with COVID-19. Retrospective investigations and clinical trials show decreased hospitalizations, severity, and mortality rates in patients receiving these medications. Nevertheless, the journey from observing something to applying it in a therapeutic setting is intricate, and the inherent diversity of the data necessitates carefully executed, forward-looking clinical trials. This review highlights the requirement for efficacious, easily obtainable, and secure COVID-19 therapeutics and identifies MET and ATO as promising treatments in this worldwide health emergency.

An ivermectin - atorvastatin combination impairs nuclear transport inhibiting dengue infection in vitro and in vivo

Dengue virus (DENV) uses cellular nuclear transport machinery to import some proteins into the nucleus. Recently, the non-structural protein 3 (NS3) of DENV was localized in the nucleus of infected cells; however, its nuclear import mechanism is still unknown. In this study, we demonstrate that Ivermectin (IVM) inhibits the nuclear localization of NS3 through the inhibition of the Importin α/β1 pathway. We also report that Atorvastatin (ATV) can modulate the nuclear transport of NS3 protease and NS5 polymerase of DENV-2. On the other hand, we found that IVM and ATV treatments reduce the alteration of nuclear pore complex (NPC) proteins, and an IVM+ATV combination reduced DENV infection both in vitro and in vivo. Hence, we conclude that ATV transport inhibition is an additional antiviral effect of this drug, suggesting a potential anti-DENV therapy in combination with IVM.

The Role of Aspartate Aminotransferase-to-Lymphocyte Ratio Index (ALRI) in Predicting Mortality in SARS-CoV-2 Infection

COVID-19 has a mortality rate exceeding 5.4 million worldwide. The early identification of patients at a high risk of mortality is essential to save their lives. The AST-to-lymphocyte ratio index (ALRI) is a novel biomarker of survival in patients with hepatocellular carcinoma, an organ susceptible to SARS-CoV-2 infection. For this study, the prognostic value of ALRI as a marker of COVID-19 mortality was evaluated. For this purpose, ALRI was compared with the main biomarkers for COVID-19 mortality (neutrophil-to-lymphocyte ratio [NLR], systemic immune-inflammation index [SII], platelet-to-lymphocyte ratio [PLR], lactate dehydrogenase (LDH)/lymphocyte ratio [LDH/LR]). A retrospective cohort of 225 patients with SARS-CoV-2 infection and without chronic liver disease was evaluated. In the non-survival group, the ALRI, NLR, SII, and LDH/LR were significantly higher than in the survival group (pcorrected < 0.05). ALRI had an area under the curve (AUC) of 0.81, a sensitivity of 70.37%, and a specificity of 75%, with a best cut-off value >42.42. COVID-19 patients with high ALRI levels had a mean survival time of 7.8 days. Multivariate Cox regression revealed that ALRI > 42.42 (HR = 2.32, 95% CI: 1.35-3.97; pcorrected = 0.01) was a prognostic factor of COVID-19 mortality. These findings prove that ALRI is an independent predictor of COVID-19 mortality and that it may help identify high-risk subjects with SARS-CoV-2 infection upon admission.

The ∆Pv-aCO2/∆Ca-vO2 ratio as a predictor of mortality in patients with severe acute respiratory distress syndrome related to COVID-19

OBJECTIVE

To evaluate the central venous-to-arterial carbon dioxide difference combined with arterial-to-venous oxygen content difference (∆Pv-aCO2/∆Ca-vO2 ratio) as a predictor of mortality in patients with COVID-19-related severe acute respiratory distress syndrome (ARDS).

METHODS

Patients admitted to the intensive care unit with severe ARDS secondary to SARS-CoV-2, and invasive mechanical ventilation were included in this single-center and retrospective cohort study performed between April 18, 2020, and January 18, 2022. The tissue perfusion indexes (lactate, central venous oxygen saturation [ScvO2], and venous-to-arterial carbon dioxide pressure difference [∆Pv-aCO2]), anaerobic metabolism index (∆Pv-aCO2/∆Ca-vO2 ratio), and severity index (Simplified Acute Physiology Score II [SAPSII]) were evaluated to determine its association with the mortality through Cox regression analysis, Kaplan-Meier curve and receiver operating characteristic (ROC) curve.

RESULTS

One hundred fifteen patients were included in the study and classified into two groups, the survivor group (n = 54) and the non-survivor group (n = 61). The lactate, ScvO2, ∆Pv-aCO2, and ∆Pv-aCO2/∆Ca-vO2 ratio medians were 1.6 mEq/L, 75%, 5 mmHg, and 1.56 mmHg/mL, respectively. The ∆Pv-aCO2/∆Ca-vO2 ratio (Hazard Ratio (HR) = 1.17, 95% confidence interval (CI) = 1.06-1.29, p = 0.001) was identified as a mortality biomarker for patients with COVID-19-related severe ARDS. The area under the curve for ∆Pv-aCO2/∆Ca-vO2 ratio was 0.691 (95% CI 0.598-0.774, p = 0.0001). The best cut-off point for ∆Pv-aCO2/∆Ca-vO2 ratio was >2.14 mmHg/mL, with a sensitivity of 49.18%, specificity of 85.19%, a positive likelihood of 3.32, and a negative likelihood of 0.6. The Kaplan-Meier curve showed that survival rates were significantly worse in patients with values greater than this cut-off point.

CONCLUSIONS

The ∆Pv-aCO2/∆Ca-vO2 ratio could be used as a predictor of mortality in patients with severe ARDS secondary to SARS-CoV-2.

Cholesterol-Lowering Drugs as Potential Antivirals: A Repurposing Approach against Flavivirus Infections

Flaviviruses, including Dengue (DENV), Zika (ZIKV), and Yellow Fever (YFV) viruses, represent a significant global health burden. The development of effective antiviral therapies against these viruses is crucial to mitigate their impact. This study investigated the antiviral potential of the cholesterol-lowering drugs atorvastatin and ezetimibe in monotherapy and combination against DENV, ZIKV, and YFV. In vitro results demonstrated a dose-dependent reduction in the percentage of infected cells for both drugs. The combination of atorvastatin and ezetimibe showed a synergistic effect against DENV 2, an additive effect against DENV 4 and ZIKV, and an antagonistic effect against YFV. In AG129 mice infected with DENV 2, monotherapy with atorvastatin or ezetimibe significantly reduced clinical signs and increased survival. However, the combination of both drugs did not significantly affect survival. This study provides valuable insights into the potential of atorvastatin and ezetimibe as antiviral agents against flaviviruses and highlights the need for further investigations into their combined therapeutic effects.

External Validation of Two Scoring Tools to Predict the Operative Duration and Open Conversion of Elective Laparoscopic Cholecystectomy in a Mexican Population

INTRODUCTION

This study aimed to evaluate the use of laparoscopic cholecystectomy (LC) operative time (CholeS score) and conversion to an open procedure (CLOC score) outside their validation dataset in Mexican population.

METHODS

Patients >18 years who underwent elective LC were analyzed in a single-center retrospective chart review study. Association between scores (CholeS and CLOC) with operative time and conversion to open procedures was assessed with Spearman correlation. The predictive accuracy of the CholeS score and CLOC score was evaluated by receiver operator characteristic.

RESULTS

200 patients were included in the study (33 excluded for emergency case or missing data). Spearman coefficient correlations between CholeS or CLOC score and operative time were 0.456 (p < 0.0001) and 0.356 (p < 0.0001), respectively. Area under the curve (AUC) for operative prediction time (>90 min) by CholeS score was 0.786 with a 3.5-point cutoff (80% sensitivity and 63.2% specificity). AUC for open conversion (CLOC score) was 0.78 with a 5-point cutoff (60% sensitivity and 91% specificity). The CLOC score had a 0.740 AUC (64% sensitivity and 72.8% specificity) for operative time >90 min.

CONCLUSIONS

The CholeS and the CLOC scores predicted LC long operative time and risk for conversion to an open procedure, respectively, outside their original validation set.

Ophthalmic manifestations in patients recovered from COVID-19 in Mexico

INTRODUCTION AND OBJECTIVES

Although the ophthalmic manifestations appear to be associated with the coronavirus disease 2019 (COVID-19), there is not enough evidence. Hence, the aim of this study was to determine the various types and frequency of ophthalmic manifestations in patients recovered from SARS-CoV-2 infection in Mexico.

MATERIAL AND METHODS

This retrospective, observational and descriptive study included all patients recovered from SARS-CoV-2 infection attending the tertiary level hospital of Mexican Social Security Institute (IMSS) from June 2020 to June 2022. During the hospital admission of patients, the demographic data such age, name, gender was recorded. Ophthalmologic examination was performed under torchlight by an ophthalmologist in the Department of Ophthalmology from IMSS. Data was compiled and statistically analyzed using Fisher's exact test and Spearman correlation.

RESULTS

A total of 3,081 SARS-CoV-2-positive patients were recorded, of which 318 (10.32%) met the inclusion criteria. Of them, 21 (6.60%) had ophthalmic manifestations and the female-to-male ratio was 1.6:1. The mean age (±SD) was 47.95 ± 15.27 years and the median (interquartile range) time from the diagnosis of COVID-19, as defined by positive SARS-CoV-2 RT-PCR testing, to detection of the ophthalmic manifestation was 31 (142) days. The most common ocular manifestation was orbital mucormycosis (23.80%). Interestingly, the presence of ophthalmic manifestations was not associated with severe COVID-19 (p = 0.665).

CONCLUSIONS

The ophthalmic manifestations are infrequent in patients recovered from severe COVID-19. Nevertheless, further large sample studies are needed to confirm these findings.

Manifestaciones oftálmicas en pacientes recuperados de COVID-19 en Mexico

Introducción y objetivos: Aunque las manifestaciones oftálmicas parecen estar asociadas a la enfermedad por coronavirus 2019 (COVID-19), no hay suficiente evidencia. Por ello, el objetivo de este estudio fue determinar los distintos tipos y la frecuencia de las manifestaciones oftálmicas en pacientes recuperados de la infección con SARS-CoV-2 en México.

Material y métodos: Este estudio retrospectivo, observacional y descriptivo incluyó a los pacientes infectados con SARS-CoV-2 de junio de 2020 a junio de 2022. El examen oftalmológico fue realizado bajo luz de linterna por un oftalmólogo del Departamento de Oftalmología. Los datos fueron analizados estadísticamente mediante la prueba exacta de Fisher y la correlación de Spearman.

Resultados: Se registraron un total de 3,081 pacientes positivos al SARS-CoV-2, de los cuales 318 (10.32%) cumplían los criterios de inclusión. De ellos, 21 (6.60%) tenían manifestaciones oftálmicas y la proporción entre mujeres y hombres era de 1.6:1. La edad media (±SD) fue 47,95 ±15,27 años y la mediana (rango intercuartil) del tiempo transcurrido desde el diagnóstico de COVID-19, definido por la prueba RT-PCR del SARS-CoV-2 positiva, hasta la detección de la manifestación oftálmica fue 31 (142) días. La manifestación ocular más común fue la mucormicosis orbital (23.80%). Interesantemente, la presencia de manifestaciones oftálmicas no fue asociada con COVID-19 grave (p= 0.665).

Conclusiones: Las manifestaciones oftálmicas son infrecuentes en los pacientes recuperados de COVID-19 grave. No obstante, se necesitan más estudios con una muestra de mayor tamaño para confirmar estos hallazgos.

Encephalitis Associated With SARS-CoV-2 Infection in a Child With Chiari Malformation Type I

BACKGROUND/AIM

There is increasing evidence that patients infected with SARS-CoV-2 develop neurological manifestations such as encephalitis. The purpose of this article was to present a case of viral encephalitis associated with SARS-CoV-2 in a 14-year-old child with Chiari malformation type I.

CASE REPORT

The patient manifested frontal headache, nausea, vomiting, skin pallor, right side Babinski sign and was diagnosed with Chiari malformation type I. He was admitted with generalized seizures and suspected encephalitis. Brain inflammation and viral RNA in the cerebrospinal fluid suggested SARS-CoV-2 encephalitis. These findings indicate that the SARS-CoV-2 test in CSF of patients with neurological manifestations, confusion, and fever during the COVID-19 pandemic should be carried out even when there is no evidence of respiratory infection. To our knowledge, this presentation of encephalitis associated with COVID-19 has not yet been reported in a patient with a congenital syndrome such as Chiari malformation type I.

CONCLUSION

Further clinical data are needed to determine the complications of encephalitis due to SARS-CoV-2 in patients with Chiari malformation type I to standardize diagnosis and treatment.

Sperm concentrations do not correlate with semen parameters and hormone profiles in males recovered from COVID-19

Background

Although the negative impact on fertility of men recovered from coronavirus disease 2019 (COVID-19) has been suggested, there is insufficient evidence, and the data are limited and contradictory. The present prospective study aimed to evaluate the sex-related hormones, semen parameters, erectile dysfunction (ED), and lower urinary tract symptoms (LUTS) in a cohort of men who recovered from COVID-19 and age-matched control men.

Methods

Semen samples were collected from twenty-two men recovered from COVID-19 with a median time of 91.5 days and thirty-six control males. The semen parameters were evaluated according to the World Health Organization (WHO) laboratory manual to examine and process human semen. The blood samples were collected to assess the male hormone profile. ED and LUTS were evaluated with the International Index of Erectile Function 5 (IIEF-5) and the International Prostate Symptom Score (IPSS), respectively.

Results

The follicle-stimulating hormone (FSH) (3.819±1.515 IU/L), luteinizing hormone (LH) (4.023±1.792 IU/L), prolactin (PRL) [12.60 (10.72-15.20) ng/mL], and testosterone (T) [4.345 (3.565-5.525) ng/mL] levels were at normal range in all males enrolled in the study. Levels of semen volume (control: 2.5 mL vs. COVID-19: 1.9 mL; P<0.05) and sperm concentration (control: 59×10⁶/mL vs. COVID-19: 41.5×10⁶/mL; P<0.005) were significantly lower in males recovered from COVID-19, but still technically well within normal regardless of WHO edition. All variables were examined through logistic regression analysis, demonstrating that only sperm concentration was an independent variable associated with men recovered from COVID-19 [odds ratio (OR) =1; 95% confidence interval (CI): 0.999-1.098; P=0.016]. According to correlation analysis, there was no correlation between sperm concentration and other semen parameters and sex-related hormone profiles. Furthermore, an absence of ED and LUTS in men who recovered from COVID-19 was evidenced using the IIEF-5 and IPSS, respectively.

Conclusions

Reproductive-age males recovered from COVID-19 have normal sperm concentration. Sperm concentration did not correlate with other semen parameters, sex-related hormones, IIEF-5, and IPSS. Further studies should be performed to evaluate whether the lower sperm concentration and semen volume that were still within the normal range are a transient or prolonged downregulation resulting from the COVID-19 attack.

Leukocyte glucose index as a novel biomarker for COVID-19 severity

The severity of coronavirus disease 2019 (COVID-19) quickly progresses with unfavorable outcomes due to the host immune response and metabolism alteration. Hence, we hypothesized that leukocyte glucose index (LGI) is a biomarker for severe COVID-19. This study involved 109 patients and the usefulness of LGI was evaluated and compared with other risk factors to predict COVID 19 severity. LGI was identified as an independent risk factor (odds ratio [OR] = 1.727, 95% confidence interval [CI]: 1.026-3.048, P = 0.041), with an area under the curve (AUC) of 0.749 (95% CI: 0.642-0.857, P < 0.0001). Interestingly, LGI was a potential risk factor (OR = 2.694, 95% CI: 1.575-5.283, Pcorrected < 0.05) for severe COVID-19 in female but not in male patients. In addition, LGI proved to be a strong predictor of the severity in patients with diabetes (AUC = 0.915 (95% CI: 0.830-1), sensitivity = 0.833, and specificity = 0.931). The AUC of LGI, together with the respiratory rate (LGI + RR), showed a considerable improvement (AUC = 0.894, 95% CI: 0.835-0.954) compared to the other biochemical and respiratory parameters analyzed. Together, these findings indicate that LGI could potentially be used as a biomarker of severity in COVID-19 patients.

Cholesterol-Rich Lipid Rafts as Platforms for SARS-CoV-2 Entry

Since its appearance, the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2), the causal agent of Coronavirus Disease 2019 (COVID-19), represents a global problem for human health that involves the host lipid homeostasis. Regarding, lipid rafts are functional membrane microdomains with highly and tightly packed lipid molecules. These regions enriched in sphingolipids and cholesterol recruit and concentrate several receptors and molecules involved in pathogen recognition and cellular signaling. Cholesterol-rich lipid rafts have multiple functions for viral replication; however, their role in SARS-CoV-2 infection remains unclear. In this review, we discussed the novel evidence on the cholesterol-rich lipid rafts as a platform for SARS-CoV-2 entry, where receptors such as the angiotensin-converting enzyme-2 (ACE-2), heparan sulfate proteoglycans (HSPGs), human Toll-like receptors (TLRs), transmembrane serine proteases (TMPRSS), CD-147 and HDL-scavenger receptor B type 1 (SR-B1) are recruited for their interaction with the viral spike protein. FDA-approved drugs such as statins, metformin, hydroxychloroquine, and cyclodextrins (methyl-β-cyclodextrin) can disrupt cholesterol-rich lipid rafts to regulate key molecules in the immune signaling pathways triggered by SARS-CoV-2 infection. Taken together, better knowledge on cholesterol-rich lipid rafts in the SARS-CoV-2-host interactions will provide valuable insights into pathogenesis and the identification of novel therapeutic targets.

Anti-flavivirus Properties of Lipid-Lowering Drugs

Although Flaviviruses such as dengue (DENV) and zika (ZIKV) virus are important human pathogens, an effective vaccine or antiviral treatment against them is not available. Hence, the search for new strategies to control flavivirus infections is essential. Several studies have shown that the host lipid metabolism could be an antiviral target because cholesterol and other lipids are required during the replicative cycle of different Flaviviridae family members. FDA-approved drugs with hypolipidemic effects could be an alternative for treating flavivirus infections. However, a better understanding of the regulation between host lipid metabolism and signaling pathways triggered during these infections is required. The metabolic pathways related to lipid metabolism modified during DENV and ZIKV infection are analyzed in this review. Additionally, the role of lipid-lowering drugs as safe host-targeted antivirals is discussed.

Case Report: Extrapulmonary Manifestations of COVID-19 and Dengue Coinfection

The risk of coronavirus disease 2019 (COVID-19) and dengue coinfection is increased in tropical countries; however, the extrapulmonary clinical manifestations have not been fully characterized. We report a 42-year-old woman whose clinical manifestations began with fever, diarrhea, headache, chest pain, myalgia, odynophagia, and arthralgia. Despite mild respiratory symptoms and normal chest computed tomography scan results, she was diagnosed with real-time reverse-transcription polymerase chain reaction (RT-PCR)-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Because she had erythema and petechiae with a decreased platelet count, the dengue NS1 antigen and anti-dengue IgM/IgG test were performed, and the Centers for Disease Control and Prevention RT-PCR assay detected the dengue virus serotype 1 infection. Additionally, increased liver enzyme serum levels were found in the patient, who later developed hepatomegaly. Hence, the mechanism of hepatic pathology associated with SARS-CoV-2 and dengue coinfection needs further research.

The importance of viral and cellular factors on flavivirus entry

The flavivirus are emerging and re-emerging arthropod-borne pathogens responsible for significant mortality and morbidity worldwide. The genus comprises more than 70 viruses, and despite genomic and structural similarities, infections by different flaviviruses result in different clinical presentations. In the absence of a safe and effective vaccine against these infections, the search for new strategies to inhibit viral infection is necessary. The life cycle of arboviruses begins with the entry process composed of multiple steps: attachment, internalization, endosomal escape and capsid uncoating. This mini-review describes factors and mechanisms involved in the viral entry as events required to take over the cellular machinery and host factors and cellular pathways commonly used by flaviviruses as possible approaches for developing broad-spectrum antiviral drugs.

The Nuclear Pore Complex Is a Key Target of Viral Proteases to Promote Viral Replication

Various viruses alter nuclear pore complex (NPC) integrity to access the nuclear content favoring their replication. Alteration of the nuclear pore complex has been observed not only in viruses that replicate in the nucleus but also in viruses with a cytoplasmic replicative cycle. In this last case, the alteration of the NPC can reduce the transport of transcription factors involved in the immune response or mRNA maturation, or inhibit the transport of mRNA from the nucleus to the cytoplasm, favoring the translation of viral mRNAs or allowing access to nuclear factors necessary for viral replication. In most cases, the alteration of the NPC is mediated by viral proteins, being the viral proteases, one of the most critical groups of viral proteins that regulate these nucleus–cytoplasmic transport changes. This review focuses on the description and discussion of the role of viral proteases in the modification of nucleus–cytoplasmic transport in viruses with cytoplasmic replicative cycles and its repercussions in viral replication.

The Regulation of Flavivirus Infection by Hijacking Exosome-Mediated Cell-Cell Communication: New Insights on Virus-Host Interactions

The arthropod-borne flaviviruses are important human pathogens, and a deeper understanding of the virus-host cell interaction is required to identify cellular targets that can be used as therapeutic candidates. It is well reported that the flaviviruses hijack several cellular functions, such as exosome-mediated cell communication during infection, which is modulated by the delivery of the exosomal cargo of pro- or antiviral molecules to the receiving host cells. Therefore, to study the role of exosomes during flavivirus infections is essential, not only to understand its relevance in virus-host interaction, but also to identify molecular factors that may contribute to the development of new strategies to block these viral infections. This review explores the implications of exosomes in flavivirus dissemination and transmission from the vector to human host cells, as well as their involvement in the host immune response. The hypothesis about exosomes as a transplacental infection route of ZIKV and the paradox effect or the dual role of exosomes released during flavivirus infection are also discussed here. Although several studies have been performed in order to identify and characterize cellular and viral molecules released in exosomes, it is not clear how all of these components participate in viral pathogenesis. Further studies will determine the balance between protective and harmful exosomes secreted by flavivirus infected cells, the characteristics and components that distinguish them both, and how they could be a factor that determines the infection outcome.

The role of anti-flavivirus humoral immune response in protection and pathogenesis

Flavivirus infections are a public health threat in the world that requires the development of safe and effective vaccines. Therefore, the understanding of the anti-flavivirus humoral immune response is fundamental to future studies on flavivirus pathogenesis and the design of anti-flavivirus therapeutics. This review aims to provide an overview of the current understanding of the function and involvement of flavivirus proteins in the humoral immune response as well as the ability of the anti-envelope (anti-E) antibodies to interfere (neutralizing antibodies) or not (non-neutralizing antibodies) with viral infection, and how they can, in some circumstances enhance dengue virus infection on Fc gamma receptor (FcγR) bearing cells through a mechanism known as antibody-dependent enhancement (ADE). Thus, the dual role of the antibodies against E protein poses a formidable challenge for vaccine development. Also, we discuss the roles of antibody binding stoichiometry (the concentration, affinity, or epitope recognition) in the neutralization of flaviviruses and the "breathing" of flavivirus virions in the humoral immune response. Finally, the relevance of some specific antibodies in the design and improvement of effective vaccines is addressed.

Isolation and characterization of exosomes released from mosquito cells infected with dengue virus

Exosomes are endocytic origin small-membrane vesicles secreted to the extracellular space by most cell types. Exosomes released from virus infected-cells can mediate the cell-to-cell communication to promote or modulate viral transmission. Dengue virus (DENV) is an arbovirus transmitted by Aedes mosquitoes bite to humans. Interestingly, the role of exosomes during the DENV infection in mammalian cells has already been described. However, little is known about exosomes derived from infected mosquito cells. Thus, the exosomes released from DENV-infected C6/36 cells were isolated, purified and analyzed using an antibody against the tetraspanin CD9 from human that showed cross-reactivity with the homologs to human CD9 found in Aedes albopictus (AalCD9). The exosomes from DENV infected cells were larger than the exosomes secreted from uninfected cells, contained virus-like particles, and they were able to infect naïve C6/36 cells, suggesting that exosomes are playing a role in virus dissemination.

Mosquito cells persistently infected with dengue virus produce viral particles with host-dependent replication

Dengue viruses (DENV) are important arboviruses that can establish a persistent infection in its mosquito vector Aedes. Mosquitoes have a short lifetime in nature which makes trying to study the processes that take place during persistent viral infections in vivo. Therefore, C6/36 cells have been used to study this type of infection. C6/36 cells persistently infected with DENV 2 produce virions that cannot infect BHK -21 cells. We hypothesized that the following passages in mosquito cells have a deleterious impact on DENV fitness in vertebrate cells. Here, we demonstrated that the viral particles released from persistently infected cells were infectious to mosquito but not to vertebrate cells. This host restriction occurs at the replication level and is associated with several mutations in the DENV genome. In summary, our findings provide new information about viral replication fitness in a host-dependent manner.

The Role of Host Cholesterol During Flavivirus Infection

In recent years the emergence and resurgence of arboviruses have generated a global health alert. Among arboviruses, Dengue (DENV), Zika (ZIKV), Yellow Fever (YFV), and West Nile (WNV) virus, belong to the genus Flavivirus, cause high viremia and occasionally fatal clinical disease in humans. Given the genetic austerity of the virus, they depend on cellular factors and organelles to complete its replication. One of the cellular components required for flavivirus infection is cholesterol. Cholesterol is an abundant lipid in biomembranes of eukaryotes cells and is necessary to maintain the cellular homeostasis. Recently, it has been reported, that cholesterol is fundamental during flavivirus infection in both mammal and insect vector models. During infection with DENV, ZIKV, YFV, and WNV the modulation of levels of host-cholesterol facilitates viral entry, replicative complexes formation, assembly, egress, and control of the interferon type I response. This modulation involves changes in cholesterol uptake with the concomitant regulation of cholesterol receptors as well as changes in cholesterol synthesis related to important modifications in cellular metabolism pathways. In view of the flavivirus dependence of cholesterol and the lack of an effective anti-flaviviral treatment, this cellular lipid has been proposed as a therapeutic target to treat infection using FDA-approved cholesterol-lowering drugs. This review aims to address the dependence of cholesterol by flaviviruses as well as the basis for anti flaviviral therapy using drugs which target is cholesterol synthesis or uptake.