Isolation and sequencing of Dashli virus, a novel Sicilian-like virus in sandflies from Iran; genetic and phylogenetic evidence for the creation of one novel species within the Phlebovirus genus in the Phenuiviridae family

Abstract

Phlebotomine sandflies are vectors of phleboviruses that cause sandfly fever or meningitis with significant implications for public health. Although several strains of these viruses had been isolated in Iran in the late 1970's, there was no recent data about the present situation at the outset of this study. Entomological investigations performed in 2009 and 2011 in Iran collected 4,770 sandflies from 10 different regions. Based on morphological identification, they were sorted into 315 pools according to species, sex, trapping station and date of capture. A phlebovirus, provisionally named Dashli virus (DASHV), was isolated from one pool of Sergentomyia spp, and subsequently DASHV RNA was detected in a second pool of Phlebotomus papatasi. Genetic and phylogenetic analyses based on complete coding genomic sequences indicated that (i) DASHV is most closely related to the Iranian isolates of Sandfly fever Sicilian virus [SFSV], (ii) there is a common ancestor to DASHV, Sandfly fever Sicilian- (SFS) and SFS-like viruses isolated in Italy, India, Turkey, and Cyprus (lineage I), (iii) DASHV is more distantly related with Corfou and Toros viruses (lineage II) although common ancestry is supported with 100% bootstrap, (iii) lineage I can be subdivided into sublineage Ia including all SFSV, SFCV and SFTV except those isolated in Iran which forms sublineage Ib (DASHV). Accordingly, we suggest to approve Sandfly fever Sicilian virus species consisting of the all aforementioned viruses. Owing that most of these viruses have been identified in human patients with febrile illness, DASHV should be considered as a potential human pathogen in Iran.

Fig 1. Geographic representation of the sandfly collection regions in Iran.

Fig 2. Phylogenetic analysis of the phlebovirus amino acid sequences: L protein.

Fig 3. Phylogenetic analysis of the phlebovirus amino acid sequences: Gn protein.

Fig 4. Phylogenetic analysis of the phlebovirus amino acid sequences: Gc protein.

Fig 5. Phylogenetic analysis of the phlebovirus amino acid sequences: Nucleocapsid protein.

Fig 6. Phylogenetic analysis of the phlebovirus amino acid sequences: Non-structural protein.

Fig 7. Phylogeny and proposed lineages and sublineages within the Sandfly fever Sicilian virus complex.

Fig 8. Distribution of evolutionary distances upon amino acid pairwise comparison of the complete open reading frame.

The genetic distance is reported on the x-axis. Frequency of genetic distances is recorded on the y-axis. Distribution of the distances observed between sequences of the L (n = 46) and N (n = 62) ORFs. The shaded square represents AA distances observed between DASHV, SFSV, TORV and CFUV strains. Intra- and interspecific-ranges are indicated.

Fig 9. Geographic dispersal of Sandfly fever Sicilian virus.