First report of multiple lineages of dengue viruses type 1 in Rio de Janeiro, Brazil

Abstract

BackgroundIn Brazil dengue has been a major public health problem since DENV-1 introduction and spread in 1986. After a low or silent co-circulation, DENV-1 re-emerged in 2009 causing a major epidemic in the country in 2010 and 2011. In this study, the phylogeny of DENV-1 strains isolated in RJ after its first introduction in 1986 and after its emergence in 2009 and 2010 was performed in order to document possible evolutionary patterns or introductions in a re-emergent virus.FindingsThe analysis of the E gene sequences demonstrated that DENV-1 isolated during 2009/2010 still belong to genotype V (Americas/Africa) but grouping in a distinct clade (lineage II) of that represented by earlier DENV-1 (lineage I). However, strains isolated in 2011 grouped together forming another distinct clade (lineage III).ConclusionsThe monitoring of DENV is important to observe the spread of potentially virulent strains as well to evaluate its impact over the population during an outbreak. Whether explosive epidemics reported in Brazil caused mainly by DENV-1 was due to lineage replacement, or due the population susceptibility to this serotype which has not circulated for almost a decade or even due to the occurrence of secondary infections in a hyperendemic country, is not clear. This is the first report of multiple lineages of DENV-1 detected in Brazil.

Population dynamics of DENV-1 genotype V in Brazil is characterized by co-circulation and strain/lineage replacement

“…L3 is the oldest Brazilian lineage and clusters isolates from different periods and regions of the country, including the prototype strain Den1BR/90 in addition to one strain from Argentina, in agreement with previous results [13,19]. When we performed the analysis with shorter sequences (2325 nt), Den1BR/90 was placed outside of lineage L3, possibly due to the use of a greater number of sequences; similar results have been observed in another study [13].…”

“…When we performed the analysis with shorter sequences (2325 nt), Den1BR/90 was placed outside of lineage L3, possibly due to the use of a greater number of sequences; similar results have been observed in another study [13]. Based on median values, the MRCA of L3 dates to 1984/85,which suggests that L3 does not share a common origin with isolates introduced into the country in the early 80 0 s, at the time of an outbreak of DENV-1 reported in the Northern Region of Brazil [6].…”

“…In our phylogenetic trees, one main cluster containing the majority of the isolates from Latin America was observed, as has been demonstrated previously [13,19,32], although some of the Brazilian isolates were located outside this cluster. The presence of different lineages of DENV-1 circulating in Latin America has been demonstrated [32], but until recently [13], all of the Brazilian isolates have grouped inside a single lineage with low genetic diversity, which was thought to be the result of a single introduction event of DENV-1 in the 80's, at the time of the first reported DENV-1 cases in Brazil [18,19,33,34]. Our analysis, based on complete genome sequences, reinforces the evidence that different lineages of DENV-1 genotype V have been introduced and have established circulation in Brazil.…”

“…Earlier phylogenetic studies of Brazilian and American DENV-1 isolates demonstrated that Brazilian DENV-1 isolates belong to genotype V, lineage I, suggesting that only one significant event of DENV-1 introduction has occurred in the country [18,19]. However, the appearance of more than one lineage of DENV-1 circulating in Brazil was reported recently [13]. Moreover, the detection of three recombinant isolates, including two Brazilian isolates, suggests that recombination among South American DENV-1 sequences is not a rare event in the evolution of this serotype [19].…”

“…The replacement or introduction of a new DENV serotype/ genotype/lineage is usually succeeded by an increase in the number of incidences and often by substantial outbreaks [11][12][13]. The replacement of the predominant DENV serotypes circulating in the country results in transmission cycles during alternating years with higher and lower incidences, but always with an overall increase in the number of cases per year [10,14].…”