Brief Review

Archives of Virology

, Volume 154, Issue 6, pp 909-918

First online:

Hytrosaviridae: a proposal for classification and nomenclature of a new insect virus family

  • Adly M. M. Abd-AllaAffiliated withEntomology Unit, FAO/IAEA Agriculture and Biotechnology Laboratory, IAEA Laboratories Seibersdorf Email author 
  • , J. M. VlakAffiliated withLaboratory of Virology, Wageningen University
  • , M. BergoinAffiliated withLaboratoire de Pathologie Comparée, Université Montpellier 2
  • , J. E. MaruniakAffiliated withDepartment of Entomology and Nematology, University of Florida
  • , A. ParkerAffiliated withEntomology Unit, FAO/IAEA Agriculture and Biotechnology Laboratory, IAEA Laboratories Seibersdorf
  • , J. P. BurandAffiliated withDepartment of Plant, Soil and Insect Science, University of Massachusetts
  • , J. A. JehleAffiliated withAgricultural Service Center Palatinate (DLR Rheinpfalz)
  • , D. G. BouciasAffiliated withDepartment of Entomology and Nematology, University of Florida
  • , Hytrosavirus Study Group of the ICTV

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Salivary gland hypertrophy viruses (SGHVs) have been identified from different dipteran species, such as the tsetse fly Glossina pallidipes (GpSGHV), the housefly Musca domestica (MdSGHV) and the narcissus bulbfly Merodon equestris (MeSGHV). These viruses share the following characteristics: (i) they produce non-occluded, enveloped, rod-shaped virions that measure 500–1,000 nm in length and 50–100 nm in diameter; (ii) they possess a large circular double-stranded DNA (dsDNA) genome ranging in size from 120 to 190 kbp and having G + C ratios ranging from 28 to 44%; (iii) they cause overt salivary gland hypertrophy (SGH) symptoms in dipteran adults and partial to complete sterility. The available information on the complete genome sequence of GpSGHV and MdSGHV indicates significant co-linearity between the two viral genomes, whereas no co-linearity was observed with baculoviruses, ascoviruses, entomopoxviruses, iridoviruses and nudiviruses, other large invertebrate DNA viruses. The DNA polymerases encoded by the SGHVs are of the type B and closely related, but they are phylogenetically distant from DNA polymerases encoded by other large dsDNA viruses. The great majority of SGHV ORFs could not be assigned by sequence comparison. Phylogenetic analysis of conserved genes clustered both SGHVs, but distantly from the nudiviruses and baculoviruses. On the basis of the available morphological, (patho)biological, genomic and phylogenetic data, we propose that the two viruses are members of a new virus family named Hytrosaviridae. This proposed family currently comprises two unassigned species, G. pallidipes salivary gland hypertrophy virus and M. domestica salivary gland hypertrophy virus, and a tentative unassigned species, M. equestris salivary gland hypertrophy virus. Here, we present the characteristics and the justification for establishing this new virus family.