Clinical and virological characterization of imported cases of Chikungunya fever (original) (raw)
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Chikungunya virus (CHIKV) is an Alphavirus belonging to the family Togaviridae. In 2006, CHIKV infection struck the Andaman and Nicobar archipelago, with an attack rate of 60%. There were more than 10 cases with acute flaccid paralysis simulating the Guillian Barre Syndrome. The majority of the patients presented severe joint pain. The cause for such an explosive nature of the outbreak with increased morbidity was not known. The isolation of CHIKV was attempted and succeeded from nine subjects presenting clinical symptoms of Chikungunya fever. The cDNA of all the isolates was se-quenced for partial E1 and nsP1 genes. Sequences were aligned based on the double locus sequence typing concept. The phylogenetic analysis shows that sequences of Andaman isolates grouped with the East, Central, and South African genotype of virus isolates from India, Sri Lanka, and Réunion. The genetic distance between Andaman isolates and the Réunion isolates was very small. The phylogenetic analysis confirmed the origin of the isolates responsible for the first ever confirmed CHIKV outbreak in these islands to be the East, Central, and South African genotype. In this manuscript, we discuss the involvement of the East, Central, and South African strain with the Chikungunya fever outbreak in this archipelago and double locus sequence typing as a first time approach. Résumé : Le virus Chikungunya (CHIKV) est un Alphavirus appartenant à la famille des Togaviridae. En 2006, une infection au CHIKV a frappé l'archipel Andaman-et-Nicobar, avec un taux d'atteinte de 60 %. Plus de 10 cas présentant une pa-ralysie flasque simulant le Syndrome de Guillain-Barré ont été rapportés. La majorité des patients présentaient des douleurs articulaires sévères. La cause d'une éclosion présentant un caractère si violent accompagné d'une morbidité élevée n'était pas connue. L'isolement de CHIKV a été tenté et réussi à partir de neuf sujets présentant des symptômes cliniques de la fiè-vre à CHIKV. L'ADNc de tous les isolats a été séquencé partiellement au niveau des gènes E1 et nsP1. Les séquences ont été alignées selon le concept du typage de séquence double locus (DLST). L'analyse phylogénique a montré que les séquen-ces des isolats d'Andaman étaient groupées avec le génotype ECSA des isolats viraux des souches de l'Inde, du Sri Lanka et des Îles de la Réunion. La distance génétique entre les isolats d'Andaman et la souche de la Réunion était très courte. L'analyse phylogénique a confirmé que l'origine des isolats responsables de la première éclosion de CHIKV jamais confir-mée dans ces îles est du génotype ECSA. Dans ce manuscrit, nous discutons de l'implication de la souche ECSA dans l'é-closion de la fièvre Chikungunya dans cet archipel et du DLST comme approche utilisée pour la première fois.
Journal of General Virology, 2007
Re-emergence of Chikungunya (CHIK), caused by CHIK virus, was recorded in India during 2005-2006 after a gap of 32 years, causing 1.3 million cases in 13 states. Several islands of the Indian Ocean reported similar outbreaks in the same period. These outbreaks were attributed to the African genotype of CHIK virus. To examine relatedness of the Indian isolates (IND-06) with Reunion Island isolates (RU), full-genome sequences of five CHIK virus isolates representative of different Indian states were determined. In addition, an isolate obtained from mosquitoes in the year 2000 (Yawat-2000), identified as being of the African genotype, and two older strains isolated in 1963 and 1973 (of the Asian genotype), were sequenced. The IND-06 isolates shared 99.9 % nucleotide identity with RU isolates, confirming involvement of the same strain in these outbreaks. The IND-06 isolates shared 98.2 % identity with the Yawat-2000 isolate. Of two crucial substitutions reported for RU isolates in the E1 region, M269V was noted in the Yawat-2000 and IND-06 isolates, whereas D284E was seen only in the IND-06 isolates. The A226V shift observed with the progression of the epidemic in Reunion Island, probably associated with adaptation to the mosquito vector, was absent in all of the Indian isolates. Three unique substitutions were noted in the IND-06 isolates: two (T128K and T376M) in the Nsp1 region and one (P23S) in the capsid protein. The two Asian strains showed 99.4 % nucleotide identity to each other, indicating relative stability of the virus. No evidence of recombination of the Asian and African genotypes, or of positive selection was observed. The results may help in understanding the association, if any, of the unique mutations with the explosive nature of the CHIK outbreak.
Genotyping of virus involved in the 2006 chikungunya outbreak in South India (Kerala and Puducherry)
An epidemic outbreak of Chikungunya virus occurred during 2006 in 15 States/Union Territories of India. The magnitude of the outbreak was unprecedented. We carried out a preliminary investigation to characterize the genotype of the virus involved in the outbreak in the State of Kerala and the Union Territory of Puducherry. We also looked into mutations in the gene sequences of the E1 region, the most informative gene of the virus on phylogeny, so as to understand the evolutionary trends of the species. The results indicate that the outbreak in Kerala and Puducherry was caused by the East Central South African (ECSA) strain of the virus. Owing to the absence of the A226V mutation in the samples analysed, it is likely that the outbreak was caused by the introduction of the ancestral stock of the Reunion clade to India, either by a human host or by the vector population. The magnitude of the outbreak might be due to mutations other than the already proposed one, i.e. A226V. Interestingly, one of the samples (Puducherry) showed a mutation K211E in the E1 gene, specific only to the Asian strain. In-depth studies are required in order to have a thorough understanding of the phylogenetic trends of the virus in India.
Molecular characterization of Chikungunya virus during an outbreak in south India
2010
Introduction: Re-emergence of Chikungunya is a major public health problem in the southern states of India. Objectives: This study was undertaken to investigate an outbreak of Chikungunya, in June-August 2008 using PCR and determine the prevalent genotypes of Chikungunya virus (CHIKV) associated with the outbreak. Materials and Methods: Samples of blood were collected (in heparinized vacutainer tubes) from suspected patients of CHIKV infection from both Government Taluk Hospital in Kerala and a tertiary care hospital in Chennai, Tamil Nadu. A one-step RT-PCR was carried out on a block thermo-cycler targeting the E2 gene that codes for the viral envelope protein. The amplicons were verified for 305 bp size by standard agarose gel electrophoresis. The PCR products were purified, sequenced, and compared with other CHIKV strains reported from different geographical regions. A phylogenetic tree was constructed using MEGA 4. Results: Altogether 118 samples were collected from patients who presented with sudden onset of fever and/or joint pain, myalgia, and headache. CHIKV infection was confirmed by RT-PCR in 14 patients and all these cases were from Kerala. The positivity correlated with the early stage of the disease as all these patients had fever of less than seven days duration. The study isolates have been allotted the GenBank accession nos. GQ272368-GQ272381. Phylogenetic analysis of recent CHIKV isolates by partial sequencing of E2 region shows that isolates are closely related to strains from neighboring states and the African type. Conclusion: RT-PCR is a useful technique for the early detection of CHIKV infection during outbreaks. Molecular characterization of the strains indicates that majority of the strains have originated from the Central/East African strains of CHIKV.
Journal of Clinical Virology Plus, 2021
Background: After the 2007 epidemic, a major outbreak of chikungunya was reported from Thiruvananthapuram, Kerala, India during 2019-2020. Study design: A cross sectional survey was conducted during the period to elucidate the clinical profile of patients and the genotype of CHIKV involved in the infections in one of the worst affected villages. Patients (n = 148) meeting WHO case definition were recruited both prospectively and retrospectively. All the samples were subjected to either RT-PCR or IgM ELISA based on the duration of symptoms. The CHIKV envelope gene sequences amplified among the positives were analyzed. Data on socio-demographic details, mosquito control practices, clinical features, details of hospitalization and treatment were collected. Results: Among the CHIKV suspected cases, 38 were recruited prospectively and 110 retrospectively. Among the former group 92% tested positive for CHIKV infection by either PCR or ELISA. Fever (51.4%) and joint pain (20.0%) were the presenting symptoms. More than 45% of the subjects had involvement of the knee joints. CHIKV Envelope gene sequence analysis indicated that all the cases belonged to the genetic lineage similar to 2006 outbreak CHIKV in Kerala. In addition, two novel non-synonymous mutations, K211E and I317V was recorded. Conclusions: The clinical presentation of Chikungunya has shown some changes compared to previous epidemic. Fever was reported to be the initial symptom of the clinical profile. Implication of the two additional mutations found in the envelope gene of the virus needs further exploration towards recent increasing trend of CHIKV infection in the state.