Dengue is a rapidly spreading acute arboviral infection transmitted through a human and Aedes mosquito cycle. Though northeast region of India has been experiencing dengue outbreaks regularly for over a decade, reports on genetic characterization of the virus from this region are limited. The present study was undertaken to detect the genotype and genetic composition of circulating dengue virus (DENV) in this region. Blood samples were collected from 918 suspected dengue patients of five northeast Indian states. Serological investigations, viz, nonstructural 1 (NS1) enzyme‐linked immunosorbent assay (ELISA), immunoglobulin M (IgM) ELISA, and immunoglobulin G (IgG) ELISA were performed followed by molecular detection. Sequence analysis and phylogenetic tree construction based on capsid‐premembrane (C‐prM) gene junction was done by BioEdit and MEGA6 software, respectively. Serological detection showed 35.34% NS1 and 18.12% IgM positivity. Secondary infection was observed in 24.53%. All four serotypes were detected. Phylogenetic analysis demonstrated circulation of genotype III of DENV‐1, genotype IV of DENV‐2, and genotype III of DENV‐3. Sequences from this region form distinct clades in the phylogenetic tree. Characterization of the C‐prM gene junction reveals divergence among the DENV strains. As genetic variation within the DENV is known to be associated with diverse clinical outcomes, information regarding the genetic composition of circulating virus could be beneficial in designing an effective intervention strategy.
BackgroundNorth-east region of India has consistent role in the spread of multi drug resistant Plasmodium (P.) falciparum to other parts of Southeast Asia. After rapid clinical treatment failure of Artemisinin based combination therapy–Sulphadoxine/Pyrimethamine (ACT-SP) chemoprophylaxis, Artemether-Lumefantrine (ACT-AL) combination therapy was introduced in the year 2012 in this region for the treatment of uncomplicated P. falciparum malaria. In a DNA sequencing based polymorphism analysis, seven codons of P. falciparum dihydropteroate synthetase (Pfdhps) gene were screened in a total of 127 P. falciparum isolates collected from Assam, Arunachal Pradesh and Tripura of North-east India during the year 2014 and 2015 to document current sulfadoxine resistant haplotypes.Materials and methodsSequences were analyzed to rearrange both nucleotide and protein haplotypes. Molecular diversity indices were analyzed in DNA Sequence Polymorphism software (DnaSP) on the basis of Pfdhps gene sequences. Disappearance from selective neutrality was assessed based on the ratio of non-synonomous to synonomous nucleotide substitutions [dN/dS ratio]. Moreover, two-tailed Z test was performed in search of the significance for probability of rejecting null hypothesis of strict neutrality [dN = dS]. Presence of mutant P. falciparum multidrug resistance protein1 (Pfmdr1) was also checked in those isolates that were present with new Pfdhps haplotypes. Phylogenetic relationship based on Pfdhps gene was reconstructed in Molecular Evolutionary Genetics Analysis (MEGA).ResultsAmong eight different sulfadoxine resistant haplotypes found, ISGNGA haplotype was documented in a total of five isolates from Tripura with association of a new mutant M538R allele. Sequence analysis of Pfmdr1 gene in these five isolates came to notice that not all but only one isolate was mutant at codon 86 (N86Y; YYSND) in the multidrug resistance protein. Molecular diversity based on Pfdhps haplotypes revealed that P. falciparum populations in Assam and Tripura were under balancing selection for sulfadoxine resistant haplotypes but population from Arunachal Pradesh was under positive selection with comparatively high haplotype diversity (h = 0.870). In reconstructed phylogenetic analysis, isolates having ISGNGA haplotype were grouped into two separate sub-clusters from the other isolates based on their genetic distances and diversities.ConclusionThis study suggests that sulfadoxine resistant isolates are still migrating from its epicenter to the other parts of Southeast Asia and hence control and elimination of the drug resistant isolates have become impedimental. Moreover, P. falciparum populations in different areas may undergo selection of particular sulfadoxine resistant haplotypes either in the presence of drug or after its removal to maintain their plasticity.
Dengue is an important vector borne disease with a great public health concern worldwide. Northeast India has experienced dengue almost every year for a decade. As studies on dengue vectors from this region are limited, we undertook an investigation to detect natural infection of the dengue virus (DENV) in potential dengue vectors of this region. Adult Aedes mosquitoes which were collected were subjected to RT-PCR for detection of infecting dengue serotype. Minimum infection rate was also determined for each positive pool. Out of the total 6229 adult Aedes mosquitoes collected, Aedes aegypti (63.3 %) was abundant in comparison to Aedes albopictus (36.7 %). These specimens (515 mosquito pools) were subjected to RT-PCR for detection of DENV-1, 2, 3 and 4. RT-PCR revealed the existence of DENV in both male as well as female mosquito pools suggesting natural transovarial transmission of DENV in this region. A total of 54 pools tested were positive for DENV-1, 2, 3 serotypes. This study revealed the occurence of DENV in both the potential dengue vectors from this region along with evidence of transovarial transmission which helps in persistence of the virus in nature.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.