Susceptibility of mosquito and lepidopteran cell lines to the mosquito iridescent virus (IIV-3) from Aedes taeniorhynchus

Mosquito iridescent viruses (MIV) are members of the genus Chloriridovirus that currently contains only the type IIV-3 from Aedestaeniorhynchus. The complete genome of invertebrate iridescent virus -3 (IIV-3) has been sequenced and the availability of a tissue culture system would facilitate functional genomic studies. This investigation, using quantitative PCR and electron microscopy, has determined that the mosquito cell lines Aedes aegypti (Aag2), Aedes albopictus (C6/36) and Anopheles gambiae (4a3A) as well as the lepidopteran cell line from Spodoptera frugiperda (SF9) are permissive to IIV-3 infection. However, IIV-3 infection remained longer in Aag2 and C6/36 cells. Virus produced in C6/36 cell line was infectious to larvae of A. taeniorhynchus by injection and per os. Ultrastructural examination of 4a3A and SF9 cells infected with IIV-3 revealed an unusual feature, where virions were localized to mitochondria. It is speculated that containment with mitochondria may play a role in the lack of persistence in these cell lines.

Increased major capsid protein expression of mosquito iridescent virus in C6/36 mosquito cells over time. Replication and release virions in C6/36 cells (Fig. A–C).Figure optionsDownload as PowerPoint slideHighlights
► Aag2 and C6/36 cell lines are susceptible to IIV-3 causing persistent infections.
► 4a3A and SF9 cell lines are permissive to IIV-3 but infections are not persistent.
► IIV-3 produced in C6/36 is infectious to mosquito larvae by injection and per os.
► Virions of IIV-3 in 4a3A and SF9 cells are localized to mitochondria.