Cytogenetic effects of measles virus fusion factor (FF) on human leukocytes

In human leukocyte cultures, extensive chromosome changes (pulverization, uncoiling, or a combination of these) induced by UV-inactivated measles virus (fusion factor or FF) (1) were virus specific, (2) showed a quantitative relationship to virus dose, and (3) were dependent upon length of virus treatment. In contrast to the above-defined extensive chromosome changes, simple chromosomal breaks showed none of these properties and could be induced by cell debris alone at rates comparable to infectious virus or FF. These observations indicate that extensive and simple chromosomal changes are morphologically distinct and sequentially unrelated, constituting two different populations of aberrations. Analysis of extensive chromosome changes after different virus exposures suggested that uncoiling is not an early and less severe form of pulverization. Localization of chromosome breakage induced by both infectious virus and FF as well as cell debris and control (medium) treated cultures was nonrandom and statistically indistinguishable.