Role of Env in resistance of feline immunodeficiency virus (FIV)-infected cats to superinfection by a second FIV strain as determined by using a chimeric virus.
A more or less pronounced resistance to superinfection by a second strain of the infecting virus has been observed in many lentivirus-infected hosts. We used a chimeric feline immunodeficiency virus (FIV), designated FIVchi, containing a large part of the env gene of a clade B virus (strain M2) and all the rest of the genome of a clade A virus (a p34TF10 molecular clone of the Petaluma strain modified to grow in lymphoid cells), to gain insights into such resistance. FIVchi was infectious and moderately pathogenic for cats and in vitro exhibited the neutralization specificity of the env donor. The experiments performed were bidirectional, in that cats preinfected with either parental virus were challenged with FIVchi and vice versa. The preinfected animals were partially or completely protected relative to what was observed in naïve control animals, most likely due, at least in part, to the circumstance that in all the preinfecting/challenge virus combinations examined, the first and the second virus shared significant viral components. Based on the proportions of complete protection observed, the role of a strongly matched viral envelope appeared to be modest and possibly dependent on the time interval between the first and the second infection. Furthermore, complete protection and the presence of measurable neutralizing antibodies capable of blocking the second virus in vitro were not associated.
Giannecchini
Simone
S
Retrovirus Center and Virology Section, Department of Experimental Pathology, University of Pisa, Via San Zeno, 37 I-56127 Pisa, Italy.
Pistello
Mauro
M
Isola
Patrizia
P
Matteucci
Donatella
D
Mazzetti
Paola
P
Freer
Giulia
G
Bendinelli
Mauro
M
D000818:Animals; D001483:Base Sequence; D002415:Cats; D002678:Chimera / Q000235:genetics / Q000276:immunology*; D004279:DNA, Viral / Q000032:analysis; D016181:Feline Acquired Immunodeficiency Syndrome / Q000276:immunology / Q000517:prevention & control*; D015694:Gene Products, rev / Q000235:genetics / Q000276:immunology*; D015752:Genes, env; D016089:Immunodeficiency Virus, Feline / Q000235:genetics / Q000276:immunology*; D008221:Lymphoid Tissue / Q000821:virology; D008969:Molecular Sequence Data; D012367:RNA, Viral / Q000097:blood
D004279:DNA, Viral; D015694:Gene Products, rev; D012367:RNA, Viral