title: A single mutation within the V3 envelope neutralization domain of feline immunodeficiency virus determines its tropism for CRFK cells.
abstract: Feline immunodeficiency virus (FIV) isolates differ in the ability to replicate in Crandell feline kidney (CRFK) cells. The difference in tropism between two variants of the Dutch isolate FIV-UT113 was studied by using molecular clones which contained the envelope genes of the variants in a background of the FIV-14 Petaluma sequence. Virus produced from clone pPET-113Th replicated in thymocytes, whereas virus from pPET-113Cr propagated in both thymocytes and CRFK cells, thereby reflecting the phenotypes of the parental variants. Exchange of envelope gene fragments showed that a 464-bp surface protein (SU)-encoding fragment encompassing the third variable region (V3) determines CRFK cell tropism. Sequence analysis of the exchanged fragments demonstrated two amino acid changes that led to an increase of the overall charge of the V3 domain: a G-->R transition at position 397 and a E-->K change at position 407. Mutational analysis of these residues revealed that the E-->K shift was responsible for the change in tropism, while the G-->R mutation improved the replication kinetics in CRFK cells. Mapping of a tropism determinant for FIV to a region which is also a major neutralization domain is reminiscent of human immunodeficiency virus type 1, in which a similar colocation was found.
authors.affiliation: Institute of Infectious Diseases and Immunology, University Utrecht, The Netherlands.
authors.forename: E J
authors.initials: EJ
authors.lastname: Verschoor
authors.forename: L A
authors.initials: LA
authors.lastname: Boven
authors.forename: H
authors.initials: H
authors.lastname: Blaak
authors.forename: A L
authors.initials: AL
authors.lastname: van Vliet
authors.forename: M C
authors.initials: MC
authors.lastname: Horzinek
authors.forename: A
authors.initials: A
authors.lastname: de Ronde
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002415:Cats; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers; D015247:Deoxyribonuclease HindIII / Q000378:metabolism; D016089:Immunodeficiency Virus, Feline / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D009500:Neutralization Tests; D014759:Viral Envelope Proteins / Q000235:genetics / Q000502:physiology*; D014779:Virus Replication / Q000235:genetics / Q000502:physiology
chemical_list: D017931:DNA Primers; D014759:Viral Envelope Proteins; D015247:Deoxyribonuclease HindIII