BACKGROUND Elite controllers (EC) are human immunodeficiency virus (HIV)-positive individuals who can maintain low viral loads for extended periods without antiretroviral therapy due to multifactorial and individual characteristics. Most have a small HIV-1 reservoir composed of identical proviral sequences maintained by clonal expansion of infected CD4+ T cells. However, some have a more diverse peripheral blood mononuclear cell (PBMC)-associated HIV-1 reservoir with unique sequences. OBJECTIVES To understand the turnover dynamics of the PBMC-associated viral quasispecies in ECs with relatively diverse circulating proviral reservoirs. METHODS We performed single genome amplification of the env gene at three time points during six years in two EC with high intra-host HIV DNA diversity. FINDINGS Both EC displayed quite diverse PBMCs-associated viral quasispecies (mean env diversity = 1.9-4.1%) across all time-points comprising both identical proviruses that are probably clonally expanded and unique proviruses with evidence of ongoing evolution. HIV-1 env glycosylation pattern suggests that ancestral and evolving proviruses may display different phenotypes of resistance to broadly neutralising antibodies consistent with persistent immune pressure. Evolving viruses may progressively replace the ancestral ones or may remain as minor variants in the circulating proviral population. MAIN CONCLUSIONS These findings support that the high intra-host HIV-1 diversity of some EC resulted from long-term persistence of archival proviruses combined with the continuous reservoir’s reseeding and low, but measurable, viral evolution despite undetectable viremia.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly spread around the world during 2020, but the precise time in which the virus began to spread locally is difficult to trace for most countries. Here, we estimate the probable onset date of the community spread of SARS-CoV-2 for heavily affected countries from Western Europe and the Americas on the basis of the cumulative number of deaths reported during the early stage of the epidemic. Our results support that SARS-CoV-2 probably started to spread locally in all western countries analysed between mid-January and mid-February 2020, thus long before community transmission was officially recognised and control measures were implemented.

Phylogenetic analyses were crucial to elucidate the origin and spread of the pandemic human immunodeficiency virus type 1 (HIV-1) group M virus, both during the pre-epidemic period of cryptic dissemination in human populations as well as during the epidemic phase of spread. The use of phylogenetics and phylodynamics approaches has provided important insights to track the founder events that resulted in the spread of HIV-1 strains across vast geographic areas, specific countries and within geographically restricted communities. In the recent years, the use of phylogenetic analysis combined with the huge availability of HIV sequences has become an increasingly important approach to reconstruct HIV transmission networks and understand transmission dynamics in concentrated and generalised epidemics. Significant efforts to obtain viral sequences from newly HIV-infected individuals could certainly contribute to detect rapidly expanding HIV-1 lineages, identify key populations at high-risk and understand what public health interventions should be prioritised in different scenarios.

BACKGROUND In Brazil, the Yellow Fever virus (YFV) is endemic in the Amazon, from where it eventually expands into epidemic waves. Coastal south-eastern (SE) Brazil, which has been a YFV-free region for eight decades, has reported a severe sylvatic outbreak since 2016. The virus spread from the north toward the south of the Rio de Janeiro (RJ) state, causing 307 human cases with 105 deaths during the 2016-2017 and 2017-2018 transmission seasons. It is unclear, however, whether the YFV would persist in the coastal Atlantic Forest of RJ during subsequent transmission seasons. OBJECTIVES To conduct a real-time surveillance and assess the potential persistence of YFV in the coastal Atlantic Forest of RJ during the 2018-2019 transmission season. METHODS We combined epizootic surveillance with fast diagnostic and molecular, phylogenetic, and evolutionary analyses. FINDINGS Using this integrative strategy, we detected the first evidence of YFV re-emergence in the third transmission season (2018-2019) in a dying howler monkey from the central region of the RJ state. The YFV detected in 2019 has the molecular signature associated with the current SE YFV outbreak and exhibited a close phylogenetic relationship with the YFV lineage that circulated in the same Atlantic Forest fragment during the past seasons. This lineage circulated along the coastal side of the Serra do Mar mountain chain, and its evolution seems to be mainly driven by genetic drift. The potential bridge vector Aedes albopictus was found probing on the recently dead howler monkey in the forest edge, very close to urban areas. MAIN CONCLUSIONS Collectively, our data revealed that YFV transmission persisted at the same Atlantic Forest area for at least three consecutive transmission seasons without the need of new introductions. Our real-time surveillance strategy permitted health authorities to take preventive actions within 48 h after the detection of the sick non-human primate. The local virus persistence and the proximity of the epizootic forest to urban areas reinforces the concern with regards to the risk of re-urbanisation and seasonal re-emergence of YFV, stressing the need for continuous effective surveillance and high vaccination coverage in the SE region, particularly in RJ, an important tourist location.

A recent study showed that infectivity of Zika virus (ZIKV) Asian genotype was enhanced by an alanine-to-valine amino acid substitution at residue 188 of the NS1 protein, but the precise time and location of origin of this mutation were not formally estimated. Here, we applied a Bayesian coalescent-based framework to estimate the age and location of the ancestral viral strain carrying the A188V substitution. Our results support that the ancestral ZIKV strain carrying the A188V substitution arose in Southeastern Asia at the early 2000s and circulated in that region for some time (5-10 years) before being disseminated to Southern Pacific islands and the Americas.

Circulation of a new dengue virus (DENV)-3 genotype was recently described in Brazil and Colombia, but the precise classification of this genotype has been controversial. Here we perform phylogenetic and nucleotide-distance analyses of the envelope gene, which support the subdivision of DENV-3 strains into five distinct genotypes (GI to GV) and confirm the classification of the new South American genotype as GV. The extremely low genetic distances between Brazilian GV strains and the prototype Philippines/L11423 GV strain isolated in 1956 raise important questions regarding the origin of GV in South America.

We recently performed a molecular epidemiology survey of human immunodeficiency virus type 1 (HIV-1) infection in Miracema, a small city in Southeast Brazil, and found multiple monophyletic clusters, consistent with independent introductions and spread of different viral lineages in the city. Here we apply Bayesian coalescent-based methods to the two largest subtype B clusters and estimate that the most recent common ancestors that gave rise to these two transmission chains were in circulation around 1991-1992. The finding that HIV-1 spread in this Brazilian small city was already taking place at a time Aids was considered a problem restricted to large urban centers may have important public health implications.