All four main serotypes of the RNA virus that causes dengue fever (DENV-1 to DENV-4) are found in Thailand. By analyzing viruses sampled over a 30 year period from patients at a Bangkok hospital, Eddie Holmes and collaborators have found that the relative abundance of each serotype fluctuates through time, as does the genetic diversity within each serotype.
Individual viral lineages or clades arise, persist and disappear. Turnover of viral clades was particularly evident in the DENV-1 serotype from the Bangkok samples. Strikingly, DENV-1 clade diversity increased as DENV-1 became more prevalent, while declines in DENV-1 abundance were correlated with clade extinctions and concommitant rises in DENV-4 prevalence.
The researchers discuss the implications of their findings in a December 2005 issue of Journal of Virology. In particular, they suggest that patterns of clade replacement in any one serotype depend on the "herd" immunologic profile of the host species, which in turn depends on infection histories with all serotypes. The authors propose that DENV-1 clades that survived declines in DENV-1 prevalence were the ones most antigenically distinct from the prevailing DENV-4 clades, because they were least likely to provoke cross protective immune reactions.
Written By: Chunlin Zhang, Mammen P. Mammen Jr, Piyawan Chinnawirotpisan, Chonticha Klungthong, Prinyada Rodpradit, Patama Monkongdee, Suchitra Nimmannitya, Siripen Kalayanarooj, & Edward C. Holmes
Journal: 79: 15123-15130
Journal Reference: 79: 15123-15130
Paper Id: 10.1128/JVI.79.24.15123-15130.2005