Figure 1.

Mutation of the feline immunodeficiency virus (FIV) Gag myristylation signal does not significantly affect virus assembly or release from transfected 293T cells. Top panel, cells were metabolically radiolabeled with [³⁵S] Met/Cys and FIV proteins were immunoprecipitated from cell and viral lysates with anti-FIV p24gag (see Materials and Methods). Virus release efficiency was calculated as the proportion of virion-associated FIV capsid compared with total (cell + virion) FIV Gag. Lower panel, virus release was determined by measuring the reverse transcriptase (RT) activity in the transfected cell medium. Error bars indicate standard error of the mean (SEM) from at least 3 independent experiments. Differences between WT and the Q5A/G6S mutant were determined to not be statistically significant by the paired Student’s t-test. PSAP- is an FIV late domain mutant that displays a severe defect in virus release [33] and thus serves as a negative control.