Phylogenetic analysis of autochthonous and imported Italian Chikungunya virus strains
Abstract number: O359
Bordi L., Castilletti C., Chiappini R., Ippolito G., Capobianchi M.R., Di Caro A., Sambri V., Cavrini F., Carletti F.
Objective: A large outbreak of Chikungunya virus (CHIKV), a mosquito-borne viral disease, has begun in the Comoro islands in 2005. In few months many other countries of the Indian Ocean have experienced a dramatic increase of cases. During the last years many imported cases in returning travellers have been detected and autochthonous cases have been recently described in Italy (Emilia Romagna), where a suitable the vector is present. Molecular characterisation of 8 Chikungunya virus isolates, 6 imported to Italy from Mauritius and from India in 2006 and 2007, 2 coming from the 2007 Italian outbreak is reported.
Methods: CHIKV sequences, targeting partial nsP1 and E1 genes, were amplified directly from serum samples from 8 and 7 patients, respectively; almost whole E1 gene sequences were obtained from virus isolates on C6/36 cells from 6 patients. RT PCR, targeting both nsP1 and E1 regions, was performed by slight modification of a previously published method
Results: Phylogenetic analysis of E1 and nsP1 showed that all strains belong to Indian Ocean cluster within the East/Central/South Africa genotype, grouping with the Indian Ocean Islands and Indian subclusters, according to geografic provenance. All the strains carried in E1 the M269V and D284E signatures of the Indian Ocean outbreak, while the A226V mutation was present in all isolates imported from Mauritius, in those imported from India in 2007 and in those from the Italian outbreak, while it was absent in the isolates imported from India in 2006
Conclusions: Our findings indicate that, during 2006 and 2007, multiple strains have been imported to Italy from countries where explosive Chikungunya outbreaks were ongoing. The presence of A226V mutation in the isolate imported from India in July 2007 and in the isolates from the 2007 Italian outbreak, originating from a case imported from India, may suggest that the virus envelope sequence of Indian strains is changing towards the spread of this mutation, with possible impact on virus spread in the vector as well as in humans.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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