High frequency of pre-existing neutralizing antibody responses in patients with dengue during an outbreak in Central Brazil

摘要

Background This study aims to identify dengue neutralizing antibody response in patients with dengue from a well-characterized cohort during an outbreak in central Brazil, 2012–2013. Methods We analyzed paired samples from 40 patients with severe dengue and 20 patients with dengue. Eligibility criteria were: IgM, NS1Ag and/or RT-PCR positivity and positive IgG result. Plaque reduction neutralization test (PRNT₅₀) from DENV-1 to DENV-4 was performed to identify serotype-specific NAbs response. An infecting serotype was defined as ≥4-fold increase in DENV NAbs in paired samples. Monotypic response was classified as PRNT₅₀?≥?1/20 to only one DENV serotype, and multitypic response was considered to be PRNT₅₀?≥?1/20 to two or more serotypes simultaneously. Results Patients were mainly adults. Virological dengue infection was confirmed by RT-PCR: DENV-4( n =?14) and DENV-1( n =?10). Forty-four out of 60(73.3?%) patients had NAbs to DENV-4, DENV-1(68.3?%), DENV-2(68.3?%) and DENV-3(61.6?%) respectively. Fifteen percent of the cases presented monotypic response, whereas 85?% had multitypic response. DENV-4 infected-patients presented the greatest difference in PRNT₅₀ titers compared with other serotypes. Pre-existing DENV NAbs was not correlated with disease severity. This was the first time that DENV-4 was implicated in an epidemic in the region. Conclusion Our data indicates high exposure of multiple DENV serotypes in all age groups in the pre-dengue vaccine era and also previous to Zika virus introduction in Brazil.