High rate of subclinical chikungunya virus infection and association of neutralizing antibody with protection in a prospective cohort in the Philippines.

Autor: Yoon IK; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand., Alera MT; Philippines-AFRIMS Virology Research Unit, Cebu City, Philippines., Lago CB; Philippines-AFRIMS Virology Research Unit, Cebu City, Philippines., Tac-An IA; Cebu City Health Department, Cebu City, Philippines., Villa D; Cebu City Health Department, Cebu City, Philippines., Fernandez S; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand., Thaisomboonsuk B; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand., Klungthong C; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand., Levy JW; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand., Velasco JM; Philippines-AFRIMS Virology Research Unit, Cebu City, Philippines., Roque VG Jr; National Epidemiology Center, Department of Health, Manila, Philippines., Salje H; Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America., Macareo LR; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand., Hermann LL; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand; Department of Medicine, University of Toronto, Toronto, Ontario, Canada., Nisalak A; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand., Srikiatkhachorn A; Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.
Jazyk: angličtina
Zdroj: PLoS neglected tropical diseases [PLoS Negl Trop Dis] 2015 May 07; Vol. 9 (5), pp. e0003764. Date of Electronic Publication: 2015 May 07 (Print Publication: 2015).
DOI: 10.1371/journal.pntd.0003764
Abstrakt: Background: Chikungunya virus (CHIKV) is a globally re-emerging arbovirus for which previous studies have indicated the majority of infections result in symptomatic febrile illness. We sought to characterize the proportion of subclinical and symptomatic CHIKV infections in a prospective cohort study in a country with known CHIKV circulation.
Methods/findings: A prospective longitudinal cohort of subjects ≥6 months old underwent community-based active surveillance for acute febrile illness in Cebu City, Philippines from 2012-13. Subjects with fever history were clinically evaluated at acute, 2, 5, and 8 day visits, and at a 3-week convalescent visit. Blood was collected at the acute and 3-week convalescent visits. Symptomatic CHIKV infections were identified by positive CHIKV PCR in acute blood samples and/or CHIKV IgM/IgG ELISA seroconversion in paired acute/convalescent samples. Enrollment and 12-month blood samples underwent plaque reduction neutralization test (PRNT) using CHIKV attenuated strain 181/clone25. Subclinical CHIKV infections were identified by ≥8-fold rise from a baseline enrollment PRNT titer <10 without symptomatic infection detected during the intervening surveillance period. Selected CHIKV PCR-positive samples underwent viral isolation and envelope protein-1 gene sequencing. Of 853 subjects who completed all study procedures at 12 months, 19 symptomatic infections (2.19 per 100 person-years) and 87 subclinical infections (10.03 per 100 person-years) occurred. The ratio of subclinical-to-symptomatic infections was 4.6:1 varying with age from 2:1 in 6 month-5 year olds to 12:1 in those >50 years old. Baseline CHIKV PRNT titer ≥10 was associated with 100% (95%CI: 46.1, 100.0) protection from symptomatic CHIKV infection. Phylogenetic analysis demonstrated Asian genotype closely related to strains from Asia and the Caribbean.
Conclusions: Subclinical infections accounted for a majority of total CHIKV infections. A positive baseline CHIKV PRNT titer was associated with protection from symptomatic CHIKV infection. These findings have implications for assessing disease burden, understanding virus transmission, and supporting vaccine development.
Databáze: MEDLINE
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