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Gag synthesis from the full-length unspliced mRNA is critical for the production of the viral progeny during human immunodeficiency virus type-1 (HIV-1) replication. While most spliced mRNAs follow the canonical gene expression pathway in which the recruitment of the nuclear cap-binding complex (CBC) and the exon junction complex (EJC) largely stimulates the rates of nuclear export and translation, the unspliced mRNA relies on the viral protein Rev to reach the cytoplasm and recruit the host translational machinery. Here, we confirm that Rev ensures high levels of Gag synthesis by driving nuclear export and translation of the unspliced mRNA. These functions of Rev are supported by the CBC subunit CBP80, which binds Rev and the unspliced mRNA in the nucleus and the cytoplasm. We also demonstrate that Rev interacts with the DEAD-box RNA helicase eIF4AI, which translocates to the nucleus and cooperates with the viral protein to promote Gag synthesis. Finally, we show that the Rev/RRE axis is important for the assembly of a CBP80-eIF4AI complex onto the unspliced mRNA. Together, our results provide further evidence towards the understanding of the molecular mechanisms by which Rev drives Gag synthesis from the unspliced mRNA during HIV-1 replication.

During retroviral replication, the full-length RNA serves both as mRNA and genomic RNA. However, the mechanisms by which the HIV-1 Gag protein selects the two RNA molecules that will be packaged into nascent virions remain poorly understood. Here, we demonstrate that deposition of N6-methyladenosine (m6A) regulates full-length RNA packaging. While m6A deposition by METTL3/METTL14 onto the full-length RNA was associated with increased Gag synthesis and reduced packaging, FTO-mediated demethylation promoted the incorporation of the full-length RNA into viral particles. Interestingly, HIV-1 Gag associates with the RNA demethylase FTO in the nucleus and contributes to full-length RNA demethylation. We further identified two highly conserved adenosines within the 5′-UTR that have a crucial functional role in m6A methylation and packaging of the full-length RNA. Together, our data propose a novel epitranscriptomic mechanism allowing the selection of the HIV-1 full-length RNA molecules that will be used as viral genomes.

N6-methyladenosine (m6A) is the most abundant internal modification present in Eukaryotic mRNA. The functions of this chemical modification are mediated by m6A-binding proteins (m6A readers) and regulated by methyltransferases (m6A writers) and demethylases (m6A erasers), which together are proposed to be responsible of a new layer of post-transcriptional control of gene expression. Despite the presence of m6A in a retroviral genome was reported more than 40 years ago, the recent development of sequencing-based technologies allowing the mapping of m6A in a transcriptome-wide manner made it possible to identify the topology and dynamics of m6A during replication of HIV-1 as well as other viruses. As such, three independent groups recently reported the presence of m6A along the HIV-1 genomic RNA (gRNA) and described the impact of cellular m6A writers, erasers and readers on different steps of viral RNA metabolism and replication. Interestingly, while two groups reported a positive role of m6A at different steps of viral gene expression it was also proposed that the presence of m6A within the gRNA reduces viral infectivity by inducing the early degradation of the incoming viral genome. This review summarizes the recent advances in this emerging field and discusses the relevance of m6A during HIV-1 replication.

Control of the COVID-19 pandemic largely depends on the effectiveness of the vaccination process. An understanding of the factors that underlie the willingness to accept vaccination contributes pivotal information to controlling the pandemic. We analyzed the association between the willingness to accept the available COVID-19 vaccines and vaccine determinants amidst the Chilean vaccination process. Individual-level survey data was collected from 744 nationally representative respondents and multivariate regression models were used to estimate the association between outcome and explanatory variables. We found that trust in COVID-19 vaccines, scientists, and medical professionals significantly increased the willingness to: accept the vaccines and booster doses, as well as annual vaccinations and the vaccination of children. Our results are critical to understanding the acceptance of COVID-19 vaccines in the context of a country with one of the world’s highest vaccination rates. We provide useful information for decision-making and policy design, in addition to establishing guidelines regarding how to effectively explain vaccination programs to citizens.

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Control of the COVID-19 pandemic largely depends on the effectiveness of the vaccination. Several factors including vaccine hesitancy can affect the vaccination process. Understanding the factors that underlie the willingness to accept vaccination brings pivotal information to control the pandemic. We analyzed the association between the willingness level to accept the COVID-19 vaccine, and vaccine determinants amidst the Chilean vaccination process. Individual-level survey data was collected from nationally representative samples of 744 respondents, and multivariate regression models used to estimate the association between outcome and explanatory variables. We found that trust in the COVID-19 vaccine, scientists, and medical professionals increased the willingness to: accept the vaccine, a booster dose, annual vaccination, and children vaccination. Our results are critical to understand the acceptance of COVID-19 vaccines in the context of a country with one of the world’s highest vaccination rates. We provide information for decision-making, policy design and communication of vaccination programs.

Translation initiation of the human immunodeficiency virus type-1 (HIV-1) unspliced mRNA has been shown to occur through cap-dependent and IRES-driven mechanisms. Previous studies suggested that the nuclear cap-binding complex (CBC) rather than eIF4E drives cap-dependent translation of the unspliced mRNA and we have recently reported that the CBC subunit CBP80 supports the function of the viral protein Rev during nuclear export and translation of this viral transcript. Ribosome recruitment during CBC-dependent translation of cellular mRNAs relies on the activity CBP80/20 translation initiation factor (CTIF), which bridges CBP80 and the 40S ribosomal subunit through interactions with eIF3g. Here, we report that CTIF restricts HIV-1 replication by interfering with Gag synthesis from the unspliced mRNA. Our results indicate that CTIF associates with Rev through its N-terminal domain and is recruited onto the unspliced mRNA ribonucleoprotein complex in order to block translation. We also demonstrate that CTIF induces the cytoplasmic accumulation of Rev impeding the association of the viral protein with CBP80. We finally show that CTIF restricts HIV-2 but not MLV Gag synthesis indicating an inhibitory mechanism conserved in Rev-expressing human lentiviruses..