Feline Immunodeficiency Virus (FIV), also called Feline T-lymphotropic Virus (FTLV), is a complex retrovirus similar to HIV. This retrovirus was originally isolated from infected cats in peripheral blood lymphocytes (Pedersen et al. 1987). Due to its induction for an immunodeficiency status in domestic cats, this retrovirus was later called FIV (Yamamoto et al. 1988a). Along with Simian Immunodeficiency Viruses (SIVs), FIV is considered to be an important AIDS infection model in small animals for helping to develop therapy against the HIV infection (Hohdatsu et al. 2000). FIV is usually inoculated through infected cat bites (Pedersen et al. 1989) and several studies suggest that male street cats are the main group of risk (Yamamoto et al. 1988b; Grindem et al. 1989). The reversion of the blood ratio between CD4+ and CD8+ lymphocytes has been reported by several authors in infected and symptomatic cats (Novotney et al. 1990; Tompkins et al. 1991; Hoffmann-Fezer et al. 1992).

The infection presents three stages of clinic symptomatology:

  1. Initial stage: Characterized by detectable viremia and a sudden reduction of CD4+ lymphocytes in the peripheral blood
  2. Asymptomatic stage: Variable, depending on the animal, and characterized by certain stability in the CD4+ levels
  3. Final stage: Identified by the classic symptomatology associated with the Immunodeficiency Syndrome.

The genomic structure of FIV is 9.4 Kb in size including LTRs of 360 nt. The internal region of this retrovirus displays a Primer Binding Site (PBS) complementary to a tRNALys3, Open Reading Frames (ORFs) for gag, pol and env genes characteristic of retroviruses, orf1 (vif) and rev (both expanded in two exons), which are two accessory genes common in other lentiviruses, orf2 (A), and adjacent to the 3´LTR the Polypurine Tract (PPT) common to other LTR retroelements (Talbott et al. 1989; Phillips et al. 1990). As other non-primate lentiviruses, FIV displays between the RNase H and INT domains, an ORF coding for a dUTPase similar to that observed in betaretroviruses, N-terminal to the PR domain (Elder et al. 1992; Payne and Elder 2001 and references therein).



Figure not to scale. If present, long terminal repeats (LTRs) have been highlighted in blue. Amino acid motifs noted with lines indicate the conserved residues in each protein domain, abbreviations below mean:

MA=matrix PR=protease DU or DUT=dUTPase TM=transmembrane TAV or IBMP=transactivator/viroplasmin or inclusion body matrix protein
CA=capsid RT=reverse transcriptase INT=Integrase CHR=chromodomain
NC=nucleocapsid RH=RNaseH SU=surface MOV=movement protein
PPT=polypurine tract PBS=primer binding site ATF=aphid transmission factor VAP=virion associated protein

Related literature

Genbank accession: M36968
Clade: Feline lentiviruses
Cluster or genus: Lentivirus
Branch or class: Class 2
Family: Retroviridae
System: LTR retroelements
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Welcome to the Gypsy Database (GyDB) an open editable database about the evolutionary relationship of viruses, mobile genetic elements (MGEs) and the genomic repeats where we invite all authors to contribute with their knowledge to improve and expand the topics.
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Llorens, C., Futami, R., Covelli, L., Dominguez-Escriba, L., Viu, J.M., Tamarit, D., Aguilar-Rodriguez, J. Vicente-Ripolles, M., Fuster, G., Bernet, G.P., Maumus, F., Munoz-Pomer, A., Sempere, J.M., LaTorre, A., Moya, A. (2011) The Gypsy Database (GyDB) of Mobile Genetic Elements: Release 2.0 Nucleic Acids Research (NARESE) 39 (suppl 1): D70-D74 doi: 10.1093/nar/gkq1061

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