Chikungunya outbreak in Montpellier, France, September to October 2014.

International audienceIn October 2014, an outbreak of 12 autochthonous chikungunya cases, 11 confirmed and 1 probable, was detected in a district of Montpellier, a town in the south of France colonised by the vector Aedes albopictus since 2010. A case returning from Cameroon living in the affected district was identified as the primary case. The epidemiological investigations and the repeated vector control treatments performed in the area and around places frequented by cases helped to contain the outbreak. In 2014, the chikungunya and dengue surveillance system in mainland France was challenged by numerous imported cases due to the chikungunya epidemic ongoing in the Caribbean Islands. This first significant outbreak of chikungunya in Europe since the 2007 Italian epidemic, however, was due to an East Central South African (ECSA) strain, imported by a traveller returning from West Africa. Important lessons were learned from this episode, which reminds us that the threat of a chikungunya epidemic in southern Europe is real

Inhibition of Hazara nairovirus replication by small interfering RNAs and their combination with ribavirin

<p>Abstract</p> <p>Background</p> <p>The genus <it>Nairovirus </it>in the family <it>Bunyaviridae </it>contains 34 tick-borne viruses classified into seven serogroups. Hazara virus (HAZV) belongs to the Crimean-Congo hemorrhagic fever (CCHF) serogroup that also includes CCHF virus (CCHFV) a major pathogen for humans. HAZV is an interesting model to study CCHFV due to a close serological and phylogenetical relationship and a classification which allows handling in a BSL2 laboratory. Nairoviruses are characterized by a tripartite negative-sense single stranded RNA genome (named L, M and S segments) that encode the RNA polymerase, the Gn-Gc glycoproteins and the nucleoprotein (NP), respectively. Currently, there are neither vaccines nor effective therapies for the treatment of any bunyavirus infection in humans. In this study we report, for the first time, the use of RNA interference (RNAi) as an approach to inhibit nairovirus replication.</p> <p>Results</p> <p>Chemically synthesized siRNAs were designed to target the mRNA produced by the three genomic segments. We first demonstrated that the siRNAs targeting the NP mRNA displayed a stronger antiviral effect than those complementary to the L and M transcripts in A549 cells. We further characterized the two most efficient siRNAs showing, that the induced inhibition is specific and associated with a decrease in NP synthesis during HAZV infection. Furthermore, both siRNAs depicted an antiviral activity when used before and after HAZV infection. We next showed that HAZV was sensitive to ribavirin which is also known to inhibit CCHFV. Finally, we demonstrated the additive or synergistic antiviral effect of siRNAs used in combination with ribavirin.</p> <p>Conclusions</p> <p>Our study highlights the interest of using RNAi (alone or in combination with ribavirin) to treat nairovirus infection. This approach has to be considered for the development of future antiviral compounds targeting CCHFV, the most pathogenic nairovirus.</p