Understanding Severe Acute Respiratory Syndrome Coronavirus 2 Replication to Design Efficient Drug Combination Therapies.

BACKGROUND: The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its disease CO-VID-19 has strongly encouraged the search for antiviral compounds. Most of the evaluated drugs against SARS-CoV-2 derive from drug repurposing of Food and Drug Administration-approved molecules. These drugs have as target three major processes: (1) early stages of virus-cell interaction, (2) viral proteases, and (3) the viral RNA-dependent RNA polymerase. SUMMARY: This review focused on the basic principles of virology and pharmacology to understand the importance of early stages of virus-cell interaction as therapeutic targets and other main processes vital for SARS-CoV-2 replication. Furthermore, we focused on describing the main targets associated with SARS-CoV-2 antiviral therapy and the rationale of drug combinations for efficiently suppressing viral replication. Key Messages: We hypothesized that blocking of both entry mechanisms could allow a more effective antiviral effect compared to the partial results obtained with chloroquine or its derivatives alone. This approach, already used to achieve an antiviral effect higher than that offered by every single drug administered separately, has been successfully applied in several viral infections such as HIV and HCV. This review will contribute to expanding the perception of the possible therapeutic targets in SARS-CoV-2 infection and highlight the benefits of using combination therapies.

Variation in Hepatitis C Virus Subtype Distribution during 20 Years in Venezuela.

OBJECTIVE: Hepatitis C virus (HCV) infection is a public health problem and a major cause of chronic hepatitis. This virus exhibits a great genetic variability, with 8 genotypes and numerous subtypes. The aim of this study was to evaluate the fluctuations of HCV subtypes during 2 decades in Venezuela. METHODS: HCV genotypes were determined by direct sequencing of the 5'-noncoding region in 392 isolates circulating in patients attended during the years 2014-2015. HCV subtype assignment was confirmed in a subset of samples (n = 24) by partial sequencing of the NS5B region. The genotype distribution was compared with the one observed in a previous study of patients followed up during the years 1994-1996 and 2005-2006. RESULTS: Some variation was observed in the HCV genotype distribution over these 20 years. HCV genotype 1b prevalence was reduced significantly from 1994-1995 to 2004-2005, as previously described, and then remained constant. During the last 10 years, a significant decrease of HCV subtype 2b (36/237 in 2005-2006 vs. 24/392 in 2014-2015, p < 0.001) was observed. Patients infected with HCV G2acj were significantly older than the ones infected with G1 (53 vs. 47 years, p = 0.004), and male sex was significantly more prevalent among G3a-infected patients compared to the other ones (71 vs. 47%, p = 0.047). CONCLUSIONS: Fluctuations in HCV subtype distribution have been observed over 2 decades in Venezuela. Different major mode of transmission and susceptibility to the available HCV treatment during each period might be playing a role in the observed fluctuations in HCV subtype distribution.

The role of the glycosyl moiety of myricetin derivatives in anti-HIV-1 activity in vitro.

BACKGROUND: Plant extracts are sources of valuable compounds with biological activity, especially for the anti-proliferative activity against pathogens or tumor cells. Myricetin is a flavonoid found in several plants that has been described as an inhibitor of Human immunodeficiency virus type 1 (HIV-1) through its action against the HIV reverse transcriptase, but myricetin derivatives have not been fully studied. The aim of this study was to evaluate the anti-HIV-1 activity of glycosylated metabolites obtained from Marcetia taxifolia and derived from myricetin: myricetin rhamnoside and myricetin 3-(6-rhamnosylgalactoside). METHODS: Compounds were obtained from organic extracts by maceration of aerial parts of M. taxifolia. All biological assays were performed in the MT4 cell line. Antiviral activity was measured as inhibition of p24 and reverse transcriptase with a fluorescent assay. RESULTS: Both flavonoids have antiviral activity in vitro, with an EC50 of 120 µM for myricetin 3-rhamnoside (MR) and 45 µM for myricetin 3-(6-rhamnosylgalactoside) (MRG), both significantly lower than the EC50 of myricetin (230 µM). Although both compounds inhibited the reverse transcriptase activity, with an IC50 of 10.6 µM for MR and 13.8 µM for MRG, myricetin was the most potent, with an IC50 of 7.6 µM, and an inhibition greater than 80%. Molecular docking approach showed correlation between the free energy of binding with the assays of enzyme inhibition. CONCLUSIONS: The results suggest that glycosylated moiety might enhance the anti-HIV-1 activity of myricetin, probably by favoring the internalization of the flavonoid into the cell. The inhibition of the HIV-1 reverse transcriptase is likely responsible for the antiviral activity.

[Present and future of therapy against hepatitis C]. / Presente y futuro de la terapia contra la hepatitis C.

Around 3% of the human population is infected with hepatitis C virus (HCV) and 70-80% of these individuals develop a chronic infection. There is no vaccine available against HCV and up to 50% of the infected patients do not respond to standard therapy, based on the combination of interferon-alpha (IFN-α) and ribavirin. Recently, direct acting antiviral drugs against HCV have been made available for treatment, leading to a significant improvement in therapeutic success. In 2014, the U.S. Food and Drug Administration approved ledipasvir plus sofosbuvir to treat the chronic infection, the first IFN- and ribavirin-free approved treatment. With such treatment, the eradication of the disease would be feasible, although drug costs are high. Host target therapy represents an emerging alternative, based on the understanding of host factors involved in the HCV infection. This therapy might show at least two theoretical benefits, increasing the number of options for therapy and raising the genetic barrier for selection of resistant variants. New treatment regimens may consist of classical therapy combined with host target-based therapy, hopefully in a synergistic manner.

[Molecular characterization of hepatitis C virus in patients referred to a reference laboratory of public health, University Hospital "Antonio Patricio de Alcalá", Cumani, Venezuela]. / Caracterización molecular del virus de la Hepatitis C en pacientes remitidos al Laboratorio Regional de Salud Pública del Hospital Universitario "Antonio Patricio de Alcalá", Cumaná, Venezuela.

The World Health Organization estimates that approximately 170 million people are chronically infected with hepatitis C virus (HCV). This study evaluated the presence of antibodies against HCV by two immunoassays. HCV genotypes were analyzed by phylogenetic analysis of viral genome fragments amplified from the 5 'non-coding (5'NC) region and non-structural region 5b (NS5b), using reverse transcription and nested polymerase chain reaction (RT-PCR), in patients referred from January 2010 to February 2013 to the Reference Laboratory of Public Health, University Hospital "Antonio Patricio de Alcalá". The prevalence of anti-HCV antibodies was 0.57% (17/3005), being the group of patients older than 41 years the most affected (0.9%). A total of 16 samples were found positive for HCV RNA by RT-PCR in the 5'NC region (16/17, 94%). Phylogenetic analysis of the 5'NC region allowed to identify the circulation of genotypes 2 and 1, and one genotype 3 and one 4. By phylogenetic analysis of the NS5b region, diverse subtypes of HCV genotype 2 were identified (2a, 2j and 2s). This finding is in accordance with previous studies that indicate that this genotype is relatively diverse in our country.

Genetic diversity of hepatitis B virus and mutations associated to hepatocellular carcinoma in patients from Venezuela, with different stages of liver disease.

Globally, about 50% of liver cancer originates as a result of long term infection with hepatitis B virus (HBV), and some genotypes and mutations have been associated with an increased severity of infection. The aim of this study was to evaluate the genetic diversity of HBV in patients from Venezuela, with chronic infection, cirrhosis and hepatocellular carcinoma (HCC) and to compare the occurrence of mutations in all patient groups. Samples from patients with different pathologies of the liver, associated with HBV infection, were collected. The HBV S region was analyzed for genotype determination and, when available, the whole genome sequence was examined for mutations analysis. Genotype F was the most common genotype (87%). While the HBV subgenotype F3 was the most frequent genotype in the whole group of samples (44%), the subgenotype F2 predominated in HCC patients (56%). Mutations were more common in HCC and cirrhosis cases (p=0.01). The A1762T mutation was significantly associated with the advanced stage of liver disease (p=0.008). Additionally, mutations were more common in early stages of liver disease in HBV subgenotype F2-infected patients, and a significant association between this subgenotype and the emergence of T 1753C, A1762T, A1762T/G1764A (p=0.04) and C1773T (p=0.001) mutations in chronic patients was found, when compared to the HBV subgenotype F3. By comparing F2 with all other HBV subgenotypes, a positive association for the three basal core promoter (BCP) mutants (A1762T, A1762T/G1764A p=0.01, G1764A p=0.04) was found. These results suggest that the HBV subgenotype F2 might be associated to more severe forms of liver disease in comparison with the HBV subgenotype F3.

Humoral Immunity across the SARS-CoV-2 Spike after Sputnik V (Gam-COVID-Vac) Vaccination.

SARS-CoV-2 vaccines have contributed to attenuating the burden of the COVID-19 pandemic by promoting the development of effective immune responses, thus reducing the spread and severity of the pandemic. A clinical trial with the Sputnik-V vaccine was conducted in Venezuela from December 2020 to July 2021. The aim of this study was to explore the antibody reactivity of vaccinated individuals towards different regions of the spike protein (S). Neutralizing antibody (NAb) activity was assessed using a commercial surrogate assay, detecting NAbs against the receptor-binding domain (RBD), and a plaque reduction neutralization test. NAb levels were correlated with the reactivity of the antibodies to the spike regions over time. The presence of Abs against nucleoprotein was also determined to rule out the effect of exposure to the virus during the clinical trial in the serological response. A high serological reactivity was observed to S and specifically to S1 and the RBD. S2, although recognized with lower intensity by vaccinated individuals, was the subunit exhibiting the highest cross-reactivity in prepandemic sera. This study is in agreement with the high efficacy reported for the Sputnik V vaccine and shows that this vaccine is able to induce an immunity lasting for at least 180 days. The dissection of the Ab reactivity to different regions of S allowed us to identify the relevance of epitopes outside the RBD that are able to induce NAbs. This research may contribute to the understanding of vaccine immunity against SARS-CoV-2, which could contribute to the design of future vaccine strategies.

[Interaction between HIV-1 and GB virus type-C during coinfection status]. / Interacción entre el virus de la inmunodeficiencia humana y el virus GB tipo-C durante el estado de co-infección.

The human immunodeficiency virus (HIV) infection is one of the most important problems in public health. It is estimated that 3 3 million people are infected around the world. HIV and GBV-C share the same transmission route, being frequent the co-infection. Since both viruses replicate in CD4+ lymphocytes, recent studies have described an interaction. Decreasing of HIV viral load and higher CD4 counts have been observed in co-infected patients, leading a better clinical outcome. Nevertheless, some epidemiological studies have shown contradictory results. Additionally, in vitro models report inhibition of HIV by E1, E2, NS3 and NS5A GBV-C proteins, resulting in a decreasing of p24 antigen. This review summarizes the principal findings about co-infection and mechanisms that have been proposed for HIV-1 inhibition.

Updates on Hepatitis B Virus (HBV) Infection 2.0.

Hepatitis B is a "silent epidemic" that is fifty to a hundred (50-100) times more infectious than HIV and is a potentially life-threatening liver infection [...].

The Hepatitis B Virus Genotypes E to J: The Overlooked Genotypes.

Hepatitis B virus (HBV) genotypes E to J are understudied genotypes. Genotype E is found almost exclusively in West Africa. Genotypes F and H are found in America and are rare in other parts of the world. The distribution of genotype G is not completely known. Genotypes I and J are found in Asia and probably result from recombination events with other genotypes. The number of reported sequences for HBV genotypes E to J is small compared to other genotypes, which could impact phylogenetic and pairwise distance analyses. Genotype F is the most divergent of the HBV genotypes and is subdivided into six subgenotypes F1 to F6. Genotype E may be a recent genotype circulating almost exclusively in sub-Saharan Africa. Genotype J is a putative genotype originating from a single Japanese patient. The paucity of data from sub-Saharan Africa and Latin America is due to the under-representation of these regions in clinical and research cohorts. The purpose of this review is to highlight the need for further research on HBV genotypes E to J, which appear to be overlooked genotypes.

Hepatitis B eradication: vaccine as a key player.

OBJECTIVE: Despite the availability of a highly effective and safe vaccine against hepatitis B virus (HBV) infection for 40 years, still almost 300 million persons are estimated to be chronically infected by this virus worldwide. The World Health Organization (WHO) has proposed a plan for hepatitis elimination by 2030. However, several factors, such as the reduction and limitation in vaccination campaigns or vaccine hesitancy (VH) in some regions of the World, might have played a role in limiting the worldwide coverage of hepatitis B prophylaxis. This review aims to describe which factors, such as VH, may be hampering the WHO 2030 goal for hepatitis B eradication. METHODS: The review describes the development and characteristics of the HBV vaccine, from the first plasma-derived to the recombinant one. Eventual limitations in its effectiveness and particularly VH were reviewed. RESULTS: The apparent pitfalls of the HBV vaccine, such as long-term effectiveness, vaccine-escape mutants, and adverse effects, were proven not to be a concern for this vaccine. However, VH persists and was even intensified by the COVID-19 pandemic. CONCLUSIONS: Many barriers still exist, such as vaccine availability, lack of awareness of the benefits of HBV vaccination, and VH. HBV VH seems to be eventually overcome in many settings with active education campaigns and information, stressing the importance of developing these strategies to achieve the 2030 goal of the WHO.

Dissemination of the Omicron Variant and Its Sub-Lineages among Residents and Travelers in Its First Year of Emergence in Venezuela.

The emergence of the SARS-CoV-2 Variant of Concern (VOC), Omicron, has been characterized by an explosive number of cases in almost every part of the world. The dissemination of different sub-lineages and recombinant genomes also led to several posterior waves in many countries. The circulation of this VOC and its major sub-lineages (BA.1 to BA.5) was monitored in community cases and in international travelers returning to Venezuela by a rapid partial sequencing method. The specific sub-lineage assignment was performed by complete genome sequencing. Epidemic waves of SARS-CoV-2 cases were observed among international travelers during 2022, a situation not seen before December 2021. The succession of the Omicron VOC sub-lineages BA.1 to BA.5 occurred sequentially, except for BA.3, which was almost not detected. However, the sub-lineages generally circulated two months earlier in international travelers than in community cases. The diversity of Omicron sub-lineages found in international travelers was related to the one found in the USA, consistent with the most frequent destination of international travel from Venezuela this year. These differences are compatible with the delay observed sometimes in Latin American countries in the circulation of the different lineages of the Omicron VOC. Once the sub-lineages were introduced in the country, community transmission was responsible for generating a characteristic distribution of them, with a predominance of sub-lineages not necessarily similar to the one observed in travelers or neighboring countries.

Neutralization of Different Variants of SARS-CoV-2 by a F(ab')2 Preparation from Sera of Horses Immunized with the Viral Receptor Binding Domain.

The Receptor Binding Domain (RBD) of SARS-CoV-2, the virus responsible for the COVID-19 pandemic, is the functional region of the viral Spike protein (S), which is involved in cell attachment to target cells. The virus has accumulated progressively mutations in its genome, particularly in the RBD region, many of them associated with immune evasion of the host neutralizing antibodies. Some of the viral lineages derived from this evolution have been classified as Variant of Interest (VOI) or Concern (VOC). The neutralizing capacity of a F(ab')2 preparation from sera of horses immunized with viral RBD was evaluated by lytic plaque reduction assay against different SARS-CoV-2 variants. A F(ab')2 preparation of a hyperimmune serum after nine immunizations with RBD exhibited a high titer of neutralizing antibodies against the ancestral-like strain (1/18,528). A reduction in the titer of the F(ab')2 preparation was observed against the different variants tested compared to the neutralizing activity against the ancestral-like strain. The highest reduction in the neutralization titer was observed for the Omicron VOC (4.7-fold), followed by the Mu VOI (2.6), Delta VOC (1.8-fold), and Gamma VOC (1.5). Even if a progressive reduction in the neutralizing antibodies titer against the different variants evaluated was observed, the serum still exhibited a neutralizing titer against the Mu VOI and the Omicron VOC (1/7113 and 1/3918, respectively), the evaluated strains most resistant to neutralization. Therefore, the preparation retained neutralizing activity against all the strains tested.

Molecular characterization of hepatitis E virus in patients with acute hepatitis in Venezuela.

Hepatitis E virus (HEV) causes a common infection in developing countries. HEV infection occurs as outbreaks, as sporadic clinical cases and as large epidemics in endemic areas. The objective of this study was to determine the presence of HEV infection in patients with clinical suspicion of hepatitis A virus (HAV) infection, referred to the Instituto Nacional de Higiene "Rafael Rangel" in Venezuela. Seventy-four sera were tested for anti-HAV and anti-HEV IgM antibodies. HEV-RNA was amplified from anti-HEV IgM positive sera using nested reverse transcription polymerase chain reaction for ORF1 (RNA dependent RNA polymerase region) and the amplicons sequenced for phylogenetic analysis. The frequency of anti-HEV IgM was 22/74 (30%) in the samples tested. Dual infection with HAV and HEV was found in 31% (12/39) of anti-HAV IgM positive patients. Viremia was detected in 3/22 (14%) of sera positive for anti-HEV IgM. Two HEV strains were classified as genotype 1 and one as genotype 3, which were closely related to Yam 67 (north of India) and US1 isolates from the USA, respectively. These findings suggest that HEV is an important cause of acute viral hepatitis in Venezuela as a single infection or co-infection with HAV, with high morbidity in children and young adults suggesting that this infection is endemic in Venezuela.

Prevalence of amino acid mutations in hepatitis C virus core and NS5B regions among Venezuelan viral isolates and comparison with worldwide isolates.

BACKGROUND: Recent reports show that R70Q and L/C91M amino acid substitutions in the core from different hepatitis C virus (HCV) genotypes have been associated with variable responses to interferon (IFN) and ribavirin (RBV) therapy, as well to an increase of hepatocellular carcinoma (HCC) risk, liver steatosis and insulin resistance (IR). Mutations in NS5B have also been associated to IFN, RBV, nucleoside and non-nucleoside inhibitors drug resistance. The prevalence of these mutations was studied in HCV RNA samples from chronically HCV-infected drug-naïve patients. METHODS: After amplification of core and NS5B region by nested-PCR, 12 substitutions were analyzed in 266 Venezuelan HCV isolates subtype 1a, 1b, 2a, 2c, 2b, 2j (a subtype frequently found in Venezuela) and 3a (n = 127 and n = 228 for core and NS5B respectively), and compared to isolates from other countries (n = 355 and n = 646 for core and NS5B respectively). RESULTS: R70Q and L/C91M core substitutions were present exclusively in HCV G1b. Both substitutions were more frequent in American isolates compared to Asian ones (69% versus 26%, p < 0.001 and 75% versus 45%, p < 0.001 respectively). In Venezuelan isolates NS5B D310N substitution was detected mainly in G3a (100%) and G1a (13%), this later with a significantly higher prevalence than in Brazilian isolates (p = 0.03). The NS5B mutations related to IFN/RBV treatment D244N was mainly found in G3a, and Q309R was present in all genotypes, except G2. Resistance to new NS5B inhibitors (C316N) was only detected in 18% of G1b, with a significantly lower prevalence than in Asian isolates, where this polymorphism was surprisingly frequent (p < 0.001). CONCLUSIONS: Genotypical, geographical and regional differences were found in the prevalence of substitutions in HCV core and NS5B proteins. The substitutions found in the Venezuelan G2j type were similar to that found in G2a and G2c isolates. Our results suggest a high prevalence of the R70Q and L/C91M mutations of core protein for G1b and D310N substitution of NS5B protein for the G3a. C316N polymorphism related with resistance to new NS5B inhibitors was only found in G1b. Some of these mutations could be associated with a worse prognosis of the disease in HCV infected patients.

Special Issue: "Updates on HBV Infection".

Hepatitis B virus (HBV) infection remains a global public health issue: a number of barriers still hamper the control of the HBV epidemic and in finding a cure for HBV [...].

SARS- CoV-2 infection and oxidative stress in early-onset preeclampsia.

SARS-CoV-2 causes coronavirus disease 2019 (COVID-19) also in pregnant women. Infection in pregnancy leads to maternal and placental functional alterations. Pregnant women with vascular defects such as preeclampsia show high susceptibility to SARS-CoV-2 infection by undefined mechanisms. Pregnant women infected with SARS-CoV-2 show higher rates of preterm birth and caesarean delivery, and their placentas show signs of vasculopathy and inflammation. It is still unclear whether the foetus is affected by the maternal infection with this virus and whether maternal infection associates with postnatal affections. The SARS-CoV-2 infection causes oxidative stress and activation of the immune system leading to cytokine storm and next tissue damage as seen in the lung. The angiotensin-converting-enzyme 2 expression is determinant for these alterations in the lung. Since this enzyme is expressed in the human placenta, SARS-CoV-2 could infect the placenta tissue, although reported to be of low frequency compared with maternal lung tissue. Early-onset preeclampsia (eoPE) shows higher expression of ADAM17 (a disintegrin and metalloproteinase 17) causing an imbalanced renin-angiotensin system and endothelial dysfunction. A similar mechanism seems to potentially account for SARS-CoV-2 infection. This review highlights the potentially common characteristics of pregnant women with eoPE with those with COVID-19. A better understanding of the mechanisms of SARS-CoV-2 infection and its impact on the placenta function is determinant since eoPE/COVID-19 association may result in maternal metabolic alterations that might lead to a potential worsening of the foetal programming of diseases in the neonate, young, and adult.

Detection of the Omicron variant of SARS-CoV-2 in international travelers returning to Venezuela.

BACKGROUND: By the end of 2021, the SARS-CoV-2 Variant of Concern (VOC) Delta was predominant in most of the world. At the end of November, the Omicron variant was first detected in South Africa. This variant was immediately classified as VOC, due to the explosive increase of cases in South Africa, and the great number of mutations exhibited by this new lineage. Since then, Omicron VOC displaced Delta one in almost every country. Venezuela implemented in May 2021 molecular testing of all the passengers arriving at Venezuelan airports. METHODS: In this study, we analyzed the presence of variants of SARS-CoV-2 in those positive samples, by sequencing a small fragment of the Spike genomic region. RESULTS: The Omicron variant was found in passengers arriving to Venezuela from the beginning of December. Complete genome analysis confirmed the presence of the Omicron VOC. The detection of this VOC coincided with an unprecedented increase in the frequency of passengers with positive nucleic acid testing. CONCLUSIONS: Genomic surveillance of samples for international travelers returning to Venezuela allowed us to rapidly detect the introduction of the Omicron variant in the country.