Antiviral resistance in influenza viruses.

Influenza represents a major threat to public health worldwide, vaccination is the most effective strategy to reduce infections. However, achieving adequate vaccination rates is challenging and vaccination does not always guarantee complete protection. For this reason, antiviral drugs represent an important measure to reduce the risk of complications in high-risk patients. However, influenza viruses have a high mutation rate which causes genetic, biochemical, and pathogenic changes that represent a challenge both for the constant replacement of vaccines and reduce their susceptibility to antiviral action. This makes it necessary to determine the mechanisms of these processes, as well as their epidemiological surveillance and, of course, the development of new therapeutic options that may be available in the event of a widespread resistance phenomenon. In this article we review some of the relevant aspects of the replicative cycle of influenza viruses, the antivirals currently used, as well as their resistance mechanisms.

A comprehensive update of the status of hepatitis C virus (HCV) infection in Mexico-A systematic review and meta-analysis (2008-2019).

INTRODUCTION AND OBJECTIVES: HCV infection is targeted by the WHO's Global Health Sector Strategy on Viral Hepatitis to be reduced notably by 2030. However, renovated epidemiological data is needed to line up with such goals. Herein, we provide an updated review of incidence, prevalence, genotypes (GTs), and risk factors (RFs) of HCV infection in Mexico to build elimination strategies. MATERIAL AND METHODS: HCV incidence was charted using the cumulative new cases/year at week 52. Prevalence, GTs, and RFs data from low-risk (LR-G) and high-risk (HR-Gs) groups were searched in PubMed/MEDLINE/Medigraphic/Scielo databases from January 2008 to December 2019 as per PRISMA guidelines. Weighted mean prevalence (WMP) was estimated; GTs and RFs were registered. RESULTS: In this study, 25,247 new cases were reported. Ten states accumulated 76.32% of HCV incidence that peaked in men at 50-59 years and women at 60-64 years. Thirty-four studies revealed a WMP between 0.774%-2.5% in LR-Gs and 11.8%-39.6% in HR-Gs that included mainly prison inmates, drug users, and dialyzed patients. GT1 and GT2 were predominant; GT3a emerged. Subtypes 1a and 1b circulate differentially, whereas novel GT2 subtypes appeared. Unsafe blood transfusion was infrequent in younger groups, but parenteral/intravenous transmission through drug-related risk behaviors has arisen. CONCLUSIONS: HCV transmission increased notably among LR-Gs and HR-Gs in Mexico. Novel genotypes/subtypes emerged as well as risky behavioral routes of transmission. A national elimination strategy will require pro-active screening in designated risk groups, research in molecular epidemiology, medical training, robust epidemiological databases, and antiviral treatment available to all eligible HCV-infected patients.

SARS-CoV-2: basic concepts, origin and treatment advances.

The first cases of COVID-19, caused by the virus called SARS-CoV-2, were recorded in Wuhan, China, in December 2019; however, its transmission ability caused for the infection to be practically present throughout the world six months later. The origin of the virus appears to be zoonotic; it has been proposed that it comes from a bat and that it may have had an intermediate host that led to its introduction in the human population. SARS-CoV-2 is an enveloped virus, with a positive single-stranded RNA genome, and it binds to the angiotensin-converting enzyme, present in susceptible cells, to infect the human respiratory system. Although other coronaviruses have been previously known, they have not had the same impact, and, therefore, research on pharmacological treatments is not sufficiently developed to face the current challenge. Almost since the beginning of the epidemic, several molecules have been proposed for the treatment of infection; however, there is not yet a drug available with sufficient effectiveness for treatment. This review describes SARS-CoV-2 main characteristics, its replicative cycle, its possible origin and some advances in the development of antiviral treatments.

Los primeros casos de COVID-19, causada por el virus denominado SARS-CoV-2, se registraron en Wuhan, China, en diciembre de 2019; sin embargo, su capacidad de transmisión ocasionó que seis meses después la infección prácticamente estuviera presente en todo el mundo. El origen del virus parece ser zoonótico; se propone que proviene del murciélago y podría haber tenido un hospedero intermediario que llevó a su introducción en la población humana. SARS-CoV-2 es un virus envuelto, con genoma de ARN de cadena sencilla en sentido positivo y se ancla a la enzima convertidora de angiotensina, presente en las células susceptibles para infectar el sistema respiratorio de los humanos. Aunque previamente se han conocido otros coronavirus, no han tenido el mismo impacto, por lo que la investigación en tratamientos farmacológicos no tiene el desarrollo suficiente para afrontar el reto actual. Casi desde el comienzo de la epidemia se han propuesto moléculas para el tratamiento de la infección, sin embargo, aún no se cuenta con un fármaco con suficiente efectividad terapéutica. En esta revisión se describen las características principales de SARS-CoV-2, su ciclo replicativo, su posible origen y algunos avances en el desarrollo de tratamientos antivirales.

Five Novel Non-Sialic Acid-Like Scaffolds Inhibit In Vitro H1N1 and H5N2 Neuraminidase Activity of Influenza a Virus.

Neuraminidase (NA) of influenza viruses enables the virus to access the cell membrane. It degrades the sialic acid contained in extracellular mucin. Later, it is responsible for releasing newly formed virions from the membrane of infected cells. Both processes become key functions within the viral cycle. Therefore, it is a therapeutic target for research of the new antiviral agents. Structure-activity relationships studies have revealed which are the important functional groups for the receptor-ligand interaction. Influenza virus type A NA activity was inhibited by five scaffolds without structural resemblance to sialic acid. Intending small organic compound repositioning along with drug repurposing, this study combined in silico simulations of ligand docking into the known binding site of NA, along with in vitro bioassays. The five proposed scaffolds are N-acetylphenylalanylmethionine, propanoic 3-[(2,5-dimethylphenyl) carbamoyl]-2-(piperazin-1-yl) acid, 3-(propylaminosulfonyl)-4-chlorobenzoic acid, ascorbic acid (vitamin C), and 4-(dipropylsulfamoyl) benzoic acid (probenecid). Their half maximal inhibitory concentration (IC50) was determined through fluorometry. An acidic reagent 2'-O-(4-methylumbelliferyl)-α-dN-acetylneuraminic acid (MUNANA) was used as substrate for viruses of human influenza H1N1 or avian influenza H5N2. Inhibition was observed in millimolar ranges in a concentration-dependent manner. The IC50 values of the five proposed scaffolds ranged from 6.4 to 73 mM. The values reflect a significant affinity difference with respect to the reference drug zanamivir (p < 0.001). Two compounds (N-acetyl dipeptide and 4-substituted benzoic acid) clearly showed competitive mechanisms, whereas ascorbic acid reflected non-competitive kinetics. The five small organic molecules constitute five different scaffolds with moderate NA affinities. They are proposed as lead compounds for developing new NA inhibitors which are not analogous to sialic acid.

Differential Transcription of SOCS5 and SOCS7 in Multiple Sclerosis Patients Treated with Interferon Beta or Glatiramer Acetate.

The participation of proinflammatory cytokines in the progression of Multiple Sclerosis (MS) has been well documented. Cytokines activate the JAK-STAT pathway, in which the suppressors of cytokine signaling (SOCS) exert a negative feedback. This paper analyzes the levels of SOCS5 and SOCS7 transcripts, quantified by RT-qPCR, in MS patients, and the concentrations of proinflammatory cytokines, IFN-γ, IL17, and IL6, determined by ELISA. Samples of peripheral blood were obtained from MS patients in the relapsing-remitting phase, treated with IFN-ß or glatiramer acetate (GA), and from healthy individuals. SOCS7 mRNA was significantly higher in patients treated with GA (1.36 ± 0.23) than in those treated with IFN-ß (0.65 ± 0.1). Regarding gender, the level of SOCS5 and SOCS7 transcripts were similar between MS and healthy females; in MS males, the level of SOCS7 transcripts were significantly lower (0.59 ± 0.03) than in healthy males (1.008 ± 0.05). Plasmatic levels of IFN-γ were significantly higher in MS patients (60 pg/mL, range 0-160) than in healthy subjects (0 range, 0-106). The same pattern was observed in MS patients treated with IFN-ß (68 pg/mL, range 0-160) compared to patients treated with GA (51 pg/mL, range 0-114), and in MS females (64 pg/mL, range 0-161) compared to healthy females (0, range 0-99). We hypothesize that the increase in SOCS7 transcription in patients treated with GA could partially explain the action mechanism of this drug, while the increase in the concentration of IFN-γ in MS patients could help elucidate the immunopathology of the disease.

Taraxacum officinale and Urtica dioica extracts inhibit dengue virus serotype 2 replication in vitro.

BACKGROUND: Urtica dioica, Taraxacum officinale, Calea integrifolia and Caesalpinia pulcherrima are widely used all over the world for treatment of different illnesses. In Mexico, these plants are traditionally used to alleviate or counteract rheumatism and inflammatory muscle diseases. In the present study we evaluated the activity of aqueous and methanolic extracts of these four plants, on the replication of dengue virus serotype 2 (DENV2). METHODS: Extraction process was carried out in a Soxtherm® system at 60, 85 and 120 °C; a chemical fractionation in silica gel chromatography was performed and compounds present in the active fractions were identified by HPLC-DAD-ESI/MSn. The cytotoxic concentration and the inhibitory effect of extracts or fractions on the DENV2 replication were analyzed in the BHK-21 cell line (plaque forming assay). The half maximal inhibitory concentration (IC50) and the selectivity index (SI) were calculated for the extracts and fractions. RESULTS: The methanolic extracts at 60 °C of T. officinale and U. dioica showed the higher inhibitory effects on DENV2 replication. After the chemical fractionation, the higher activity fraction was found for U. dioica and T. officinale, presenting IC50 values of 165.7 ± 3.85 and 126.1 ± 2.80 µg/ml, respectively; SI values were 5.59 and 6.01 for each fraction. The compounds present in T. officinale, were luteolin and caffeoylquinic acids derivatives and quercertin diclycosides. The compounds in the active fraction of U. dioica, were, chlorogenic acid, quercertin derivatives and flavonol glycosides (quercetin and kaempferol). CONCLUSIONS: Two fractions from U. dioica and T. officinale methanolic extracts with anti-dengue activity were found. The compounds present in both fractions were identified, several recognized molecules have demonstrated activity against other viral species. Subsequent biological analysis of the molecules, alone or in combination, contained in the extracts will be carried out to develop therapeutics against DENV2.

Hepatic mobilization of zinc after an experimental surgery, and its relationship with inflammatory cytokines release, and expression of metallothionein and Zip14 transporter.

OBJECTIVE: To study the relationship between the release of inflammatory cytokines and mobilization of zinc into liver, and the expression of metallothionein and Zip14 transporter after an abdominal surgery in rats. MATERIALS: Thirty-five male Wistar rats were subjected to experimental surgical stress, then the subgroups of five animals were killed at 3, 6, 9, 12, 16, 20 and 24 h. Matched groups without surgery were used as controls. METHODS: Zinc levels were determined by AAS, intracellular zinc by zinquin and dithizone staining. Hepatic metallothionein was assayed by a Cd-saturation method, and IL-1ß, IL-6, and TNF-ß by immunoassays. Zip14 expression was analyzed by real-time RT-PCR, and protein level by immunohistochemistry and Western blot. RESULTS: Experimental surgery produced a hypozincemia, and the increase of hepatic zinc also produced the release of IL-1ß, IL-6 in serum, and the increase of hepatic MT. Histochemistry showed a decrease of free zinc at 3-6 h, but an increase at 9 h (zinquin); meanwhile, total intracellular zinc increased after 9 h (dithizone). RNAm and protein levels of Zip14 were elevated between 6 and 20 h after surgery. CONCLUSION: Biochemical changes described in this work could be part of the APR, and directed to respond to the damage produced during surgical trauma.

Human papillomavirus infections in Mexican women with normal cytology, precancerous lesions, and cervical cancer: type-specific prevalence and HPV coinfections.

The prevalence and genotype distribution of human papillomavirus (HPV) provides the basis for designing HPV prevention programs. The prevalence rates of type-specific HPV and coinfections in samples of Mexican women were investigated in 822 women aged 18-87 years. HPV detection was performed using a Linear Array™ genotyping test. HPV infection was found in 12.4% of controls, 46.3% of those with cervical intraepithelial neoplasia 1, and 100% of those with cervical intraepithelial neoplasia 3 or cervical cancer. HPV 16 was the most prevalent type in all diagnosis groups. The HPV types most frequently found in cervical cancers were 16, 18, 45, 52, 58, and 39; HPV types 16, 62, 51, 84, 18, 53, and CP6108 were the most prevalent in control women. Considering HPV-positive samples only, coinfections occurred most often in controls (63%) and were less frequent in those with cervical cancer (26%). The most frequent viral types in coinfections with HPV 16 in control women were HPV 62, 51, and 84; in women with cervical cancers, HPV 18, 39, and 70 were most common. In conclusion, in addition to HPV types 16 and 18, types 45, 39, 58, 52, and 71 were found in cervical cancers in Mexican women (78%); among them, only 65% were attributable to HPV types 16 and 18. Therefore, it is necessary to consider these viral types in the design of new vaccines, and to determine whether certain HPV types coinfecting with HPV 16 in precursor lesions determine tumor progression or regression.

Chemoenzymatic Syntheses of Sialylated Oligosaccharides Containing C5-Modified Neuraminic Acids for Dual Inhibition of Hemagglutinins and Neuraminidases.

A fast chemoenzymatic synthesis of sialylated oligosaccharides containing C5-modified neuraminic acids is reported. Analogues of GM3 and GM2 ganglioside saccharidic portions where the acetyl group of NeuNAc has been replaced by a phenylacetyl (PhAc) or a propanoyl (Prop) moiety have been efficiently prepared with metabolically engineered E. coli bacteria. GM3 analogues were either obtained by chemoselective modification of biosynthetic N-acetyl-sialyllactoside (GM3 NAc) or by direct bacterial synthesis using C5-modified neuraminic acid precursors. The latter strategy proved to be very versatile as it led to an efficient synthesis of GM2 analogues. These glycomimetics were assessed against hemagglutinins and sialidases. In particular, the GM3 NPhAc displayed a binding affinity for Maackia amurensis agglutinin (MAA) similar to that of GM3 NAc, while being resistant to hydrolysis by Vibrio cholerae (VC) neuraminidase. A preliminary study with influenza viruses also confirmed a selective inhibition of N1 neuraminidase by GM3 NPhAc, suggesting potential developments for the detection of flu viruses and for fighting them.

Interferon lambda inhibits dengue virus replication in epithelial cells.

BACKGROUND: In viral disease, infection is controlled at the cellular level by type I interferon (IFN-I), but dengue virus (DENV) has the ability to inhibit this response. Type III interferon, also known as lambda IFN (IFN-III or IFN-λ), is a complementary pathway to the antiviral response by IFN-I. This work analyzed the IFN-λ (IFN-III) mediated antiviral response against DENV serotype 2 (DENV-2) infection. METHODS: Dengue fever patients were sampled to determine their IFN-λ levels by ELISA. To study the IFN-λ response during DENV infection we selected the epithelial cell line C33-A, and we demonstrated that it is permissive to DENV-2 infection. The effect of IFN-λ on virus replication was determined in these cells, in parallel to the expression of IFN-stimulated genes (ISGs), and Suppressor of Cytokine Signaling (SOCS), genes measured by RT-qPCR. RESULTS: We found increased (~1.8 times) serological IFN-λ in dengue fever patients compared to healthy blood donors. IFN-λ inhibited DENV-2 replication in a dose-dependent manner in vitro. The reduction of viral titer corresponded with increased ISG mRNA levels (MX1 and OAS1), with the highest inhibition occurring at ISG's peak expression. Presence of IFN-negative regulators, SOCS1 and SOCS3, during DENV-2 infection was associated with reduced IFN-λ1 expression. CONCLUSIONS: Evidence described here suggests that IFN-λ is a good candidate inhibitor of viral replication in dengue infection. Mechanisms for the cellular and organismal interplay between DENV and IFN- λ need to be further studied as they could provide insights into strategies to treat this disease. Furthermore, we report a novel epithelial model to study dengue infection in vitro.

Detection of hepatitis C virus RNA in saliva of patients with active infection not associated with periodontal or liver disease severity.

BACKGROUND: Hepatitis C virus (HCV) is mainly transmitted by parenteral route, being blood transfusion and intravenous drug use the most frequent risk factors. However, it has been suggested that there are other routes of transmission. There are several studies where HCV RNA has been detected in saliva of patients infected with HCV, and epidemiological studies have proposed the dental treatments as possible risk factors for HCV transmission. The purpose of this study was to detect the presence of HCV RNA in saliva of patients with active infection and associating with periodontal or liver disease. METHODS: Patients with quantifiable HCV-RNA in serum were enrolled in the study. Periodontal disease was assessed using the modified gingival index (MGI). Presence of dental plaque was assessed with the use of disclosing tablets. Patients were clinically and laboratory evaluated to identify the stage of liver disease, the HCV RNA was determinate in saliva by nested RT-PCR. To determine associations between different parameters univariate and multivariate analysis were used. RESULTS: A total of 45 patients were included. Of these patients, 21 (46.6%) had hepatitis, 23 (51.1%) had cirrhosis and one patient (2.4%) presented hepatocellular carcinoma (HCC). Viral loads in serum ranged from 2.31-6.68 log IU/ml with a mean of 5.46 log IU/ml (95% CI 5.23-5.70). HCV RNA was positive in saliva of 29 patients (64.4%) and was not detected in 16 (35.6%). For univariate analysis three independent variables were associated with the detection of HCV-RNA in saliva: gender, viral load and dental plaque and multivariate analysis only one independent variable viral load >5.17 log IU/mL remained significantly associated with the detection of HCV in saliva (p = 0.0002). A statistical difference was observed when viral load was analyzed, log 5.85 IU/mL (95% CI 5.67-6.02) for patients with HCV in saliva vs. log 4.77 IU/mL (95% CI 4.35-5.19) for patients without HCV in saliva (p = 0.0001). The detection of HCV-RNA in saliva was more frequent in patients with relatively high serum viral loads. CONCLUSION: HCV-RNA in saliva was associated with the level of serum viral load but not with periodontal or liver disease severity.

Hepatitis C virus infection in patients and family members attending two primary care clinics in Puebla, Mexico.

BACKGROUND: Approximately 180 million persons (~2.8%) globally are estimated to be infected by hepatitis C virus (HCV). HCV prevalence in Mexico has been estimated to be between 1.2 and 1.4%. The aim of present work was to determine the prevalence of HCV infection in patients and family members attending two primary care clinics in Puebla, Mexico. MATERIAL AND METHODS: Patients and their accompanying family members in two clinics were invited to participate in this study between May and September 2010. RESULTS: A total of 10,214 persons were included in the study; 120 (1.17%) persons were anti-HCV reactive. Of the reactive subjects, detection of viral RNA was determined in 114 subjects and 36 were positive (31%). The more frequent risk factors were having a family history of cirrhosis (33.1%) and having a blood transfusion prior to 1995 (29%). After a multiple logistic regression analysis only transfusion prior to 1995 resulted significant to HCV transmission (p = 0.004). The overall detected HCV genotypes were as follows: 1a (29%), 1b (48.5%), 2/2b (12.8%), and 3a (6.5%). CONCLUSION: The HCV prevalence in this population is in agreement with previous studies in other regions of Mexico.

Comparative Review of the State of the Art in Research on the Porcine Epidemic Diarrhea Virus and SARS-CoV-2, Scope of Knowledge between Coronaviruses.

This review presents comparative information corresponding to the progress in knowledge of some aspects of infection by the porcine epidemic diarrhea virus (PEDV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coronaviruses. PEDV is an alphacoronavirus of great economic importance due to the million-dollar losses it generates in the pig industry. PEDV has many similarities to the SARS-CoV-2 betacoronavirus that causes COVID-19 disease. This review presents possible scenarios for SARS-CoV-2 based on the collected literature on PEDV and the tools or strategies currently developed for SARS-CoV-2 that would be useful in PEDV research. The speed of the study of SARS-CoV-2 and the generation of strategies to control the pandemic was possible due to the knowledge derived from infections caused by other human coronaviruses such as severe acute respiratory syndrome (SARS) and middle east respiratory syndrome (MERS). Therefore, from the information obtained from several coronaviruses, the current and future behavior of SARS-CoV-2 could be inferred and, with the large amount of information on the virus that causes COVID-19, the study of PEDV could be improved and probably that of new emerging and re-emerging coronaviruses.

Age and Comorbidities as Risk Factors for Severe COVID-19 in Mexico, before, during and after Massive Vaccination.

During 2020-2023, Mexico had a large COVID-19 emergency with >331,000 adult deaths and one of the highest excess mortalities worldwide. Age at COVID-19 death has been lower in Mexico than in high-income countries, presumably because of the young demographics and high prevalence of chronic metabolic diseases in young and middle-aged adults. SARS-CoV-2 vaccination covered 85% of adults with at least one dose and 50% with booster(s) up to April 2022. No new vaccination efforts or updated boosters were introduced until October 2023; thus, we explored the public health impact of massive SARS-CoV-2 vaccination against ancestral strains and asked whether their real-world protection has persisted through time. We compared three periods with respect to vaccine roll-outs: before, during and after vaccine introduction in a national retrospective cohort of >7.5 million COVID-19 cases. The main findings were that after vaccination, COVID-19 mortality decreased, age at COVID-19 death increased by 5-10 years, both in populations with and without comorbidities; obesity stopped being a significant risk factor for COVID-19 death and protection against severe disease persisted for a year after boosters, including at ages 60-79 and 80+. Middle-aged adults had the highest protection from vaccines/hybrid immunity and they more than halved their proportions in COVID-19 deaths.

Donated Blood Screening for HIV, HCV and HBV by ID-NAT and the Residual Risk of Iatrogenic Transmission in a Tertiary Care Hospital Blood Bank in Puebla, Mexico.

Hepatitis C virus (HCV), human immunodeficiency virus (HIV) and hepatitis B virus (HBV) can be transmitted by blood transfusion. Most transmission occurs during the acute viremic phase (AVP), before antibody development. To reduce transmission risk, individual donor nucleic acid testing (ID-NAT) is used. In Puebla, Mexico, serological tests and ID-NAT have been applied to screen blood donors and detect individuals in AVP. In the present study, 106,125 blood donors' data in two periods (2012-2015 and 2017-2019) were analyzed. The residual risk (RR) values were calculated considering ID-NAT results. The RR for HIV was 14 in 1 million donations or 1 in 71,428, the RR for HVC was 6.8 in 1 million donations or 1 in 147,058 and, for HBV, it was 156 in 1 million donations, or 1 in 6410. Previously, it was predicted that the transmission RR of these viruses would be reduced in Mexico through better screening with NAT. The use of ID-NAT has, indeed, increased the safety of blood reserves for HIV and HCV. However, more research is needed to determine why the residual risk of HBV did not decrease as much over the study period. ID-NAT is an important complementary tool for blood donor screening that should be implemented.

Chronic Comorbidities in Middle Aged Patients Contribute to Ineffective Emergency Hematopoiesis in Covid-19 Fatal Outcomes.

BACKGROUND AND AIMS: Mexico is among the countries with the highest estimated excess mortality rates due to the COVID-19 pandemic, with more than half of reported deaths occurring in adults younger than 65 years old. Although this behavior is presumably influenced by the young demographics and the high prevalence of metabolic diseases, the underlying mechanisms have not been determined. METHODS: The age-stratified case fatality rate (CFR) was estimated in a prospective cohort with 245 hospitalized COVID-19 cases, followed through time, for the period October 2020-September 2021. Cellular and inflammatory parameters were exhaustively investigated in blood samples by laboratory test, multiparametric flow cytometry and multiplex immunoassays. RESULTS: The CFR was 35.51%, with 55.2% of deaths recorded in middle-aged adults. On admission, hematological cell differentiation, physiological stress and inflammation parameters, showed distinctive profiles of potential prognostic value in patients under 65 at 7 days follow-up. Pre-existing metabolic conditions were identified as risk factors of poor outcomes. Chronic kidney disease (CKD), as single comorbidity or in combination with diabetes, had the highest risk for COVID-19 fatality. Of note, fatal outcomes in middle-aged patients were marked from admission by an inflammatory landscape and emergency myeloid hematopoiesis at the expense of functional lymphoid innate cells for antiviral immunosurveillance, including NK and dendritic cell subsets. CONCLUSIONS: Comorbidities increased the development of imbalanced myeloid phenotype, rendering middle-aged individuals unable to effectively control SARS-CoV-2. A predictive signature of high-risk outcomes at day 7 of disease evolution as a tool for their early stratification in vulnerable populations is proposed.

Neuropathological Aspects of SARS-CoV-2 Infection: Significance for Both Alzheimer's and Parkinson's Disease.

Evidence suggests that SARS-CoV-2 entry into the central nervous system can result in neurological and/or neurodegenerative diseases. In this review, routes of SARS-Cov-2 entry into the brain via neuroinvasive pathways such as transcribrial, ocular surface or hematogenous system are discussed. It is argued that SARS-Cov-2-induced cytokine storm, neuroinflammation and oxidative stress increase the risk of developing neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Further studies on the effects of SARS-CoV-2 and its variants on protein aggregation, glia or microglia activation, and blood-brain barrier are warranted.

Decrease in COVID-19 adverse outcomes in adults during the Delta and Omicron SARS-CoV-2 waves, after vaccination in Mexico.

Mexico, one of the countries severely affected by COVID-19, accumulated more than 5. 1 all-cause excess deaths/1,000 inhabitants and 2.5 COVID-19 confirmed deaths/1,000 inhabitants, in 2 years. In this scenario of high SARS-CoV-2 circulation, we analyzed the effectiveness of the country's vaccination strategy that used 7 different vaccines from around the world, and focused on vaccinating the oldest population first. We analyzed the national dataset published by Mexican health authorities, as a retrospective cohort, separating cases, hospitalizations, deaths and excess deaths by wave and age group. We explored if the vaccination strategy was effective to limit severe COVID-19 during the active outbreaks caused by Delta and Omicron variants. Vaccination of the eldest third of the population reduced COVID-19 hospitalizations, deaths and excess deaths by 46-55% in the third wave driven by Delta SARS-CoV-2. These adverse outcomes dropped 74-85% by the fourth wave driven by Omicron, when all adults had access to vaccines. Vaccine access for the pregnant resulted in 85-90% decrease in COVID-19 fatalities in pregnant individuals and 80% decrease in infants 0 years old by the Omicron wave. In contrast, in the rest of the pediatric population that did not access vaccination before the period analyzed, COVID-19 hospitalizations increased >40% during the Delta and Omicron waves. Our analysis suggests that the vaccination strategy in Mexico has been successful to limit population mortality and decrease severe COVID-19, but children in Mexico still need access to SARS-CoV-2 vaccines to limit severe COVID-19, in particular those 1-4 years old.

In silico testing of flavonoids as potential inhibitors of protease and helicase domains of dengue and Zika viruses.

Background: Dengue and Zika are two major vector-borne diseases. Dengue causes up to 25,000 deaths and nearly a 100 million cases worldwide per year, while the incidence of Zika has increased in recent years. Although Zika has been associated to fetal microcephaly and Guillain-Barré syndrome both it and dengue have common clinical symptoms such as severe headache, retroocular pain, muscle and join pain, nausea, vomiting, and rash. Currently, vaccines have been designed and antivirals have been identified for these diseases but there still need for more options for treatment. Our group previously obtained some fractions from medicinal plants that blocked dengue virus (DENV) infection in vitro. In the present work, we explored the possible targets by molecular docking a group of molecules contained in the plant fractions against DENV and Zika virus (ZIKV) NS3-helicase (NS3-hel) and NS3-protease (NS3-pro) structures. Finally, the best ligands were evaluated by molecular dynamic simulations. Methods: To establish if these molecules could act as wide spectrum inhibitors, we used structures from four DENV serotypes and from ZIKV. ADFR 1.2 rc1 software was used for docking analysis; subsequently molecular dynamics analysis was carried out using AMBER20. Results: Docking suggested that 3,5-dicaffeoylquinic acid (DCA01), quercetin 3-rutinoside (QNR05) and quercetin 3,7-diglucoside (QND10) can tightly bind to both NS3-hel and NS3-pro. However, after a molecular dynamics analysis, tight binding was not maintained for NS3-hel. In contrast, NS3-pro from two dengue serotypes, DENV3 and DENV4, retained both QNR05 and QND10 which converged near the catalytic site. After the molecular dynamics analysis, both ligands presented a stable trajectory over time, in contrast to DCA01. These findings allowed us to work on the design of a molecule called MOD10, using the QND10 skeleton to improve the interaction in the active site of the NS3-pro domain, which was verified through molecular dynamics simulation, turning out to be better than QNR05 and QND10, both in interaction and in the trajectory. Discussion: Our results suggests that NS3-hel RNA empty binding site is not a good target for drug design as the binding site located through docking is too big. However, our results indicate that QNR05 and QND10 could block NS3-pro activity in DENV and ZIKV. In the interaction with these molecules, the sub-pocket-2 remained unoccupied in NS3-pro, leaving opportunity for improvement and drug design using the quercetin scaffold. The analysis of the NS3-pro in complex with MOD10 show a molecule that exerts contact with sub-pockets S1, S1', S2 and S3, increasing its affinity and apparent stability on NS3-pro.

Predicted 3D model of the M protein of Porcine Epidemic Diarrhea Virus and analysis of its immunogenic potential.

The membrane protein M of the Porcine Epidemic Diarrhea Virus (PEDV) is the most abundant component of the viral envelope. The M protein plays a central role in the morphogenesis and assembly of the virus through protein interactions of the M-M, M-Spike (S) and M-nucleocapsid (N) type. The M protein is known to induce protective antibodies in pigs and to participate in the antagonistic response of the cellular antiviral system coordinated by the type I and type III interferon pathways. The 3D structure of the PEDV M protein is still unknown. The present work exposes a predicted 3D model of the M protein generated using the Robetta protocol. The M protein model is organized into a transmembrane and a globular region. The obtained 3D model of the PEDV M protein was compared with 3D models of the SARS-CoV-2 M protein created using neural networks and with initial machine learning-based models created using trRosetta. The 3D model of the present study predicted four linear B-cell epitopes (RSVNASSGTG and KHGDYSAVSNPSALT peptides are noteworthy), six discontinuous B-cell epitopes, forty weak binding and fourteen strong binding T-cell epitopes in the CV777 M protein. A high degree of conservation of the epitopes predicted in the PEDV M protein was observed among different PEDV strains isolated in different countries. The data suggest that the M protein could be a potential candidate for the development of new treatments or strategies that activate protective cellular mechanisms against viral diseases.