Binding Evolution of the Dengue Virus Envelope Against DC-SIGN: A Combined Approach of Phylogenetics and Molecular Dynamics Analyses Over 30 Years of Dengue Virus in Brazil.

The Red Queen Hypothesis (RQH), derived from Lewis Carroll's "Through the Looking-Glass", postulates that organisms must continually adapt in response to each other to maintain relative fitness. Within the context of host-pathogen interactions, the RQH implies an evolutionary arms race, wherein viruses evolve to exploit hosts and hosts evolve to resist viral invasion. This study delves into the dynamics of the RQH in the context of virus-cell interactions, specifically focusing on virus receptors and cell receptors. We observed multiple virus-host systems and noted patterns of co-evolution. As viruses evolved receptor-binding proteins to effectively engage with cell receptors, cells countered by altering their receptor genes. This ongoing mutual adaptation cycle has influenced the molecular intricacies of receptor-ligand interactions. Our data supports the RQH as a driving force behind the diversification and specialization of both viral and host cell receptors. Understanding this co-evolutionary dance offers insights into the unpredictability of emerging viral diseases and potential therapeutic interventions. Future research is crucial to dissect the nuanced molecular changes and the broader ecological consequences of this ever-evolving battle. Here, we combine phylogenetic inferences, structural modeling, and molecular dynamics analyses to describe the epidemiological characteristics of major Brazilian DENV strains that circulated from 1990 to 2022 from a combined perspective, thus providing us with a more detailed picture on the dynamics of such interactions over time.

Discovery of a Potent and Selective Chikungunya Virus Envelope Protein Inhibitor through Computer-Aided Drug Design.

The worldwide expansion of chikungunya virus (CHIKV) into tropical and subtropical areas in the last 15 years has posed a currently unmet need for vaccines and therapeutics. The E2-E1 envelope glycoprotein complex binds receptors on the host cell and promotes membrane fusion during CHIKV entry, thus constituting an attractive target for the development of antiviral drugs. In order to identify CHIKV antivirals acting through inhibition of the envelope glycoprotein complex function, our first approach was to search for amenable druggable sites within the E2-E1 heterodimer. We identified a pocket located in the interface between E2 and E1 around the fusion loop. Then, via a structure-based virtual screening approach and in vitro assay of antiviral activity, we identified compound 7 as a specific inhibitor of CHIKV. Through a lead optimization process, we obtained compound 11 that demonstrated increased antiviral activity and low cytotoxicity (EC50 1.6 µM, CC50 56.0 µM). Molecular dynamics simulations were carried out and described a possible interaction pattern of compound 11 and the E1-E2 dimer that could be useful for further optimization. As expected from target site selection, compound 11 inhibited virus internalization during CHIKV entry. In addition, virus populations resistant to compound 11 included mutation E2-P173S, which mapped to the proposed binding pocket, and second site mutation E1-Y24H. Construction of recombinant viruses showed that these mutations conferred antiviral resistance in the parental background. Finally, compound 11 presents acceptable solubility values and is chemically and enzymatically stable in different media. Altogether, these findings uncover a suitable pocket for the design of CHIKV entry inhibitors with promising antiviral activity and pharmacological profiles.

In vitro inhibitory effect of maraviroc on the association of the simian immunodeficiency virus envelope glycoprotein with CCR5.

Asian macaques infected with simian immunodeficiency viruses (SIVs) isolated from African non-human primates develop a disease similar to human AIDS. SIV enters its target cells by binding to CD4 and a coreceptor, typically CCR5. Maraviroc is an entry inhibitor of human immunodeficiency virus type 1 (HIV-1) that prevents the interaction between CCR5 and the surface subunit gp120 of the viral envelope glycoprotein (Env). Thus far, the activity of maraviroc on SIV entry has been poorly studied. Here, we determined in vitro pharmacological parameters of the effect of maraviroc on the SIV Env association with CCR5. Cell-to-cell fusion inhibition assays were used to compare the susceptibility to maraviroc of the SIVsmmPBj Env-CCR5 interaction with that of HIV-1BaL Env. Analysis of dose-response curves and determination of IC50 values demonstrate that increasing concentrations of maraviroc inhibit the membrane fusion activity of SIVsmmPBj Env in a manner and to an extent similar to that of HIV-1BaL Env.

Insights on Zika virus envelope gene conservation in American outbreaks.

Phylogenetic studies with Zika virus (ZIKV) have been conducted in Brazil. In this study, we sequenced 8 new sequences of the ZIKV envelope (E) gene from strains of cases from the Paraná and Mato Grosso do Sul states in 2016. A low phylogenetic signal was observed, with more than 40% of unresolved quartets, and the Maximum Likelihood Tree grouped all sequences in the Brazilian branches within the Asian genotype. In addition, a Shannon entropy analysis was conducted, showing a high stability in the E protein through the ZIKV polyprotein. Taken together, these results suggest a high degree of conservation in the ZIKV E gene from the recent American outbreaks.

Homologous prime-boost with Zika virus envelope protein and poly (I:C) induces robust specific humoral and cellular immune responses.

The recent outbreaks of Zika virus (ZIKV) infection and the potential association with Guillain-Barré syndrome in adults and with congenital abnormalities have highlighted the urgency for an effective vaccine. The ZIKV Envelope glycoprotein (EZIKV) is the most abundant protein on the virus surface, and has been evaluated together with the pre-membrane protein (prM) of the viral coat as a vaccine candidate in clinical trials. In this study, we performed a head-to-head comparison of the immune response induced by different EZIKV-based vaccine candidates in mice. We compared different platforms (DNA, recombinant protein), adjuvants (poly (I:C), CpG ODN 1826) and immunization strategies (homologous, heterologous). The hierarchy of adjuvant potency showed that poly (I:C) was a superior adjuvant than CpG ODN. While poly (I:C) assisted immunization reached a plateau in antibody titers after two doses, the CpG ODN group required an extra immunization dose. Besides, the administration of poly (I:C) induced higher EZIKV-specific cellular immune responses than CpG ODN. We also show that immunization with homologous prime-boost EZIKV protein + poly (I:C) regimen induced a more robust humoral response than homologous DNA (pVAX-EZIKV) or heterologous regimens (DNA/protein or protein/DNA). A detailed analysis of cellular immune responses revealed that homologous (EZIKV + poly (I:C)) and heterologous (pVAX-EZIKV/EZIKV + poly (I:C)) prime-boost regimens induced the highest magnitude of IFN-γ secreting cells and cytokine-producing CD4+ T cells. Overall, our data demonstrate that homologous EZIKV + poly (I:C) prime-boost immunization is sufficient to induce more robust specific-EZIKV humoral and cellular immune responses than the other strategies that contemplate homologous DNA (pVAX-EZIKV) or heterologous (pVAX-EZIKV/EZIKV + poly (I:C), and vice-versa) immunizations.

Current Understanding of the Role of Cholesterol in the Life Cycle of Alphaviruses.

Enveloped viruses rely on different lipid classes present in cell membranes to accomplish several steps of their life cycle in the host. Particularly for alphaviruses, a medically important group of arboviruses, which are part of the Togaviridae family, cholesterol seems to be a critical lipid exploited during infection, although its relevance may vary depending on which stage of the virus life cycle is under consideration and whether infection takes place in vertebrate or invertebrate hosts. In this review, the role of cholesterol in both early and late events of alphavirus infection and how viral replication may affect cholesterol metabolism are summarized, taking into account studies on Old World and New World alphaviruses in different cell lines. Moreover, the importance of cholesterol for the structural stability of alphavirus particles is also discussed, shedding light on the role played by this lipid when they leave the host cell.