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. 2018 Apr 19;12(4):e0006435.
doi: 10.1371/journal.pntd.0006435. eCollection 2018 Apr.

Vector competence of Italian Aedes albopictus populations for the chikungunya virus (E1-226V)

Francesco Severini  1 , Daniela Boccolini  1 , Claudia Fortuna  2 , Marco Di Luca  1 , Luciano Toma  1 , Antonello Amendola  2 , Eleonora Benedetti  2 , Giada Minelli  3 , Roberto Romi  1 , Giulietta Venturi  2 , Giovanni Rezza  2 , Maria Elena Remoli  2
Affiliations

Vector competence of Italian Aedes albopictus populations for the chikungunya virus (E1-226V)

Francesco Severini et al. PLoS Negl Trop Dis. .

Abstract

Background: Chikungunya virus (CHIKV) is an emerging arbovirus, belonging to the Togaviridae family, Alphavirus genus, transmitted by Aedes spp. mosquitoes. Since 2007, two different CHIKV strains (E1-226A and E1-226V) have been responsible for outbreaks in European countries, including Italy, sustained by Ae. albopictus mosquitoes.

Findings: In this study, we assessed the susceptibility to the CHIKV E1-226V, strain responsible for the Italian 2007 outbreak, of eight Ae. albopictus populations collected in Northern, Central, Southern, and Island Italy, by experimental infections. Vector competence was evaluated by estimating infection, dissemination, and transmission rates (IR, DR, TR), through detection of the virus in the bodies, legs plus wings, and saliva, respectively. Additionally, vertical transmission was evaluated by the detection of the virus in the offspring. The results of our study demonstrated that the Italian populations of Ae. albopictus tested were susceptible to CHIKV infection, and can disseminate the virus outside the midgut barrier with high values of IR and DR. Viral infectious RNA was detected in the saliva of three populations from Central, Southern, and Island Italy, also tested for TR and population transmission rate (PTR) values. No progeny of the first and second gonotrophic cycle were positive for CHIKV.

Conclusions: This study strongly confirms the role of Ae. albopictus as a potential CHIKV vector in Italy. This may represent a threat, especially considering both the high density of this species, which is widespread throughout the country, and the increasing number of cases of imported arboviruses.

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Conflict of interest statement

The authors declare that no competing interests exist.

Figures

Fig 1
Fig 1. Description of Aedes albopictus populations.
Locations and filial generations (F) of the Italian Ae. albopictus populations experimentally infected with CHIKV.
Fig 2
Fig 2. Transmission of CHIKV (E1-226V) in Aedes albopictus populations from Central, Southern, and Island Italy.
(A) Mosquito saliva samples were collected at 0, 2, 3, 7, and 12 days post exposure (d.p.e.) to an infectious CHIKV blood meal. Population transmission rate (PTR) and the viral mean titer, calculated by qRT-PCR and expressed in PFUeq/mL, were analyzed for all collection time; the number within the grey columns (in square bracket) represent the number of tested mosquitoes analyzed for the presence of the virus in the saliva. (B) The cumulative transmission rate (TR) and PTR of analyzed Ae. albopictus populations were calculated from 3 to 12 d.p.e. TR corresponding to the proportion of mosquitoes with positive saliva with respect to the number of mosquitoes with positive body [+S/+B]; PTR corresponding to the proportion of mosquitoes with positive saliva among the total number of tested fed mosquitoes [+S/tested].
See this image and copyright information in PMC

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