Genetic divergence of Chikungunya virus plaque variants from the Comoros Island (2005).
Chikungunya virus (CHIKV) from a human sample collected during the 2005 Chikungunya outbreak in the Comoros Island, showed distinct and reproducible large (L2) and small (S7) plaques which were characterized in this study. The parent strain and plaque variants were analysed by in vitro growth kinetics in different cell lines and their genetic similarity assessed by whole genome sequencing, comparative sequence alignment and phylogenetic analysis. In vitro growth kinetic assays showed similar growth patterns of both plaque variants in Vero cells but higher viral titres of S7 compared to L2 in C6/36 cells. Amino acids (AA) alignments of the CHIKV plaque variants and S27 African prototype strain, showed 30 AA changes in the non-structural proteins (nsP) and 22 AA changes in the structural proteins. Between L2 and S7, only two AAs differences were observed. A missense substitution (C642Y) of L2 in the nsP2, involving a conservative AA substitution and a nonsense substitution (R524X) of S7 in the nsP3, which has been shown to enhance O'nyong-nyong virus infectivity and dissemination in Anopheles mosquitoes. The phenotypic difference observed in plaque size could be attributed to one of these AA substitutions. Phylogenetic analysis showed that the parent strain and its variants clustered closely together with each other and with Indian Ocean CHIKV strains indicating circulation of isolates with close evolutionary relatedness in the same outbreak. These observations pave way for important functional studies to understand the significance of the identified genetic changes in virulence and viral transmission in mosquito and mammalian hosts.
Department of Biochemistry, University of Nairobi, P. O. Box 30197-00100, Nairobi, Kenya. cwasonga@gmail.com.|Arbovirus/Viral Haemorrhagic Fever Laboratory, Kenya Medical Research Institute (KEMRI), P. O. Box 54840-00200, Nairobi, Kenya. cwasonga@gmail.com.
Caroline
C
Wasonga
Department of Virology, Institute of Tropical Medicine, Nagasaki University, 1-12-4, Sakamoto, Nagasaki, 852-8523, Japan.
Shingo
S
Inoue
Department of Biological Sciences, International Livestock Research Institute, P. O. Box 3079- 00100, Nairobi, Kenya.
Cecilia
C
Rumberia
Department of Biological Sciences, International Livestock Research Institute, P. O. Box 3079- 00100, Nairobi, Kenya.
George
G
Michuki
Production Department, Kenya Medical Research Institute (KEMRI), P. O. Box 54840-00200, Nairobi, Kenya.
James
J
Kimotho
Medical Laboratory Sciences Department, Jomo Kenyatta University of Agriculture and Technology, P. O. Box 62000-00200, Nairobi, Kenya.|Molecular Biology and Bioinformatics Unit, International Centre of Insect Physiology and Ecology, P. O. Box 30772 - 00100, Nairobi, Kenya.
Juliette R
JR
Ongus
Arbovirus/Viral Haemorrhagic Fever Laboratory, Kenya Medical Research Institute (KEMRI), P. O. Box 54840-00200, Nairobi, Kenya.
Rosemary
R
Sang
Department of Emerging Infectious Diseases, United States Army Medical Research Unit - Kenya, P. O. Box 606 - 00621, Village Market, Nairobi, Kenya.
Lillian
L
Musila
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000852:Anopheles / Q000821:virology; D001483:Base Sequence; D002460:Cell Line; D065632:Chikungunya Fever / Q000635:transmission / Q000821:virology*; D002646:Chikungunya virus / Q000235:genetics* / Q000254:growth & development; D002522:Chlorocebus aethiops; D017507:Comoros; D004196:Disease Outbreaks; D040961:Genetic Drift; D014644:Genetic Variation; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016415:Sequence Alignment; D014709:Vero Cells; D017361:Viral Nonstructural Proteins
D017361:Viral Nonstructural Proteins
Chikungunya virus; Comoros Island; Genetic variation; Variants