A Comparison of the Tipula and Sericesthis Iridescent Viruses

Abstract

SUMMARYA direct experimental comparison of the Tipula iridescent virus and the Sericesthis iridescent virus has shown them to be very similar but not identical. After extensive purification the viruses were differentiated by electrophoretic mobility, tryptic peptide patterns, serological cross-reactivity, and pathogenicity in a group of host insects. The viruses were identical in gross chemical composition and in a number of physical properties. A particle weight of i-z to I'3 x io 9 daltons was calculated by three methods. A slower sedimenting top component consisting of empty protein shells was found during the purification of each virus; similar empty shells could be produced by succinylation or formic acid-diphenylamine treatment of whole virus.

Proposals for a new classification of iridescent viruses

“…Likewise, IV21 (Helicoverpa armigera IV) and IV28 (Lethocerus IV) were almost indistinguishable. IV1 (Tipula IV) and IV2 (Sericesthis IV) did not show many REN profile similarities, indicating that these are more distantly related than previously suggested (Glitz et al, 1968). As expected, IV3 (mosquito IV) and the vertebrate viruses FV3 and FLCDV appeared distinct from all the other isolates.…”

“…IV1 belongs to the largest group of inter-related isolates. IV2 (Sericesthis IV) has often been used in comparative studies with IVs that have been discovered subsequently (Bellet & Fenner, 1968;Glitz et al, 1968;Kalmakoff et al, 1972;Kelly & Avery, 1974;Elliott et aI., 1977;Kelly et al, 1979;Moore & Kelly, 1980). IV1 and IV2 have been described as strains of the same virus (Glitz et al, 1968;Willis, 1990).…”

Icosahedral Cytoplasmic Deoxyriboviruses

“…African swine fever virus does not cross-react serologically with FV3 (Came and Dardiri, 1969), iridescent virus type 1, or lymphocystis virus Kaminski et al, 1969). Iridescent virus types 1, 2, 9, 10, 16, 17, 18, and 19 show cross-reactivity but are not identical when examined by immunoprecipitation tests (Cunningham and Tinsley, 1968;Kalmakoff and Robertson, 1970;Glitz et al, 1968;Kalmakoff et al, 1972). Iridescent virus types 3 and 12 are related to each other but do not possess antigens in common with types I, 2, 6, 9, and 10 (Tinsley et aI., Cunningham and Tinsley, 1968).…”

“…The ratios of the various phospholipid classes of the virion and of those of host cells, as well as the low amount of cholesterol present in the virions, led to the conclusion that the viral membrane was not derived from preexisting host membranes. Early reports (Thomas, 1961;Glitz et al, 1968) of the presence of lipid (5 %) in iridescent viruses were considered to represent casual cellular contaminant (Bellett, 1968). However, recently, lipid extracted from purified iridescent virus type 2 and type 6 and analyzed by thin-layer chromatography was found to be different from that of the host cell (Kelly and Vance, 1973).…”

The regular mosquito iridescent virus (RMIV) in the black saltmarsh mosquito, Aedes taeniorhynchus (Wiedemann): production, purification, transovarial transmission, site of entry, development of infec by Stephen Carson Hembree.

“…Nevertheless, the iridescent viruses of insects are generally considered to be closely related (Bellett, 1968;Bellett and Inman, 1967;Cunningham and Tinsley, 1968;Glitz et al . , 1968;Wildy, 1971).…”