The first complete viral genome sequence of the Zika virus circulating in the Americas
The Institut Pasteur in French Guiana has just sequenced the complete viral genome of the Zika virus that causes an unprecedented outbreak in the tropical area of the American continent. Analyses of this viral sequence, published in The Lancet, show that there is a quasi-total homology with the strains responsible for epidemics in the Pacific region in 2013 and 2014.
Last November, the Virology laboratory in the Institut Pasteur in French Guiana (National reference centre for Arboviruses in the French Antilles and Guiana) confirmed the first five cases of indigenous Zika virus infection in Suriname. From one of these samples, researchers from the Institut Pasteur in French Guiana sequenced the complete viral genome of the strain. Analyses of this viral sequence, published in The Lancet*, show that it belongs to the Asian lineage of Zika virus and reveal more than 99% homology to the strain responsible for the outbreak in French Polynesia in 2013.
"Until now, only few complete viral sequences and none from the strain currently circulating in the Americas were available. Obtaining the complete viral genome sequence is a major base to better understand the virus evolution." says Dr. Dominique Rousset, in charge of the Virology laboratory and the National reference centre for Arboviruses.
In May 2015, first cases of Zika virus infection were confirmed in Brazil. Today, the country faces an unprecedented outbreak: 440,000 to 1,300,000 suspected cases according to Brazilian Health authorities. The virus has also rapidly spread and affects 10 countries in the tropical area of the American continent and Caribbean. Whereas the infection was considered as benign until recently, the epidemics of 2013-2014 in the Pacific region had occurred along with severe neurological syndromes (as Guillain-Barré syndrome) and congenital brain malformations. In Brazil, the significant increase in microcephaly in newborns whose mothers were infected during pregnancy led the government to declare a public health emergency in December 2015.
"Are these anomalies only due to Zika virus, or are they also caused by the co-circulation of other infectious pathogens or other factors? Interdisciplinary research projects have to be set up to answer these questions. We are already working to better understand the virus and its evolution, which requires a reinforcement of diagnostic tools in particular." says Dr. Dominique Rousset.
17 cases of Zika virus infection have been confirmed in French Guiana, and 3 in Martinique. The Institut Pasteur in French Guiana is strongly mobilized in epidemiological surveillance, partnering with Health authorities and the Institut Pasteur International Network (IPIN). "We are committed in supporting anti-vectorial measures through the monitoring of insecticide resistance in association with the Regional Health Agency. Researches on vector competence in Aedes aegypti for different arboviruses including Zika virus are carried out in the Vectopole" says Dr. Isabelle Dusfour, entomologist at the Institut Pasteur in French Guiana.
Furthermore, a team of 4 researchers from the Institut Pasteur in Dakar (Senegal) directed by Dr. Amadou Sall have joined Brazilian scientists to face the outbreak (collaboration with the University of São Paulo).
[*]: Enfissi et al., Zika virus genome from the Americas, The Lancet, 7 January 2016.