Copackaging of different-sized retroviral genomic RNAs: little effect on retroviral replication or recombination.

We tested the effect of copackaging retroviral vectors of different sizes on retroviral replication and recombination. Our results indicate little or no difference in replication or in the rate or pattern of the strand transfers leading to the formation of recombinant proviruses with size. The size difference of the vectors also allowed us to extend our previous analysis of the linkage of markers in the recombinant proviruses. We conclude that the observed linkage is inconsistent with the strand displacement/assimilation model of retroviral recombination.