Autoradiographic studies of HeLa-S3 cells persistently infected with hemadsorption type 2 virus

Parainfluenza viruses

Human parainfluenza viruses (HPIV) were first discovered in the late 1950s. Over the last decade, considerable knowledge about their molecular structure and function has been accumulated. This has led to significant changes in both the nomenclature and taxonomic relationships of these viruses. HPIV is genetically and antigenically divided into types 1 to 4. Further major subtypes of HPIV-4 (A and B) and subgroups/genotypes of HPIV-1 and HPIV-3 have been described. HPIV-1 to HPIV-3 are major causes of lower respiratory infections in infants, young children, the immunocompromised, the chronically ill, and the elderly. Each subtype can cause somewhat unique clinical diseases in different hosts. HPIV are enveloped and of medium size (150 to 250 nm), and their RNA genome is in the negative sense. These viruses belong to the Paramyxoviridae family, one of the largest and most rapidly growing groups of viruses causing significant human and veterinary disease. HPIV are closely related to recently discovered megamyxoviruses (Hendra and Nipah viruses) and metapneumovirus.

Two-step chromosomal control of tumorigenicity of Chinese hamster cells in nude mice

A simple method for microinjecting isolated chromosomes into a single living cell under an inverted microscope has been developed. Of the 368 injected cells, 85 were able to form a colony and could be cloned. Clones of Chinese hamster V79 cells microinjected with chromosomes isolated from murine D56 cells [V79 (D56) cells] were tested for tumorigenicity in immunodeficient nude mice and for colony-forming ability in soft agar. Untreated recipient V79 cells were highly tumorigenic and had a high colony-forming ability in soft agar. In contrast, two out of the 21 microinjected clones tested were non-tumorigenic in nude mice and had only weak colony-forming ability in soft agar. The chromosome banding pattern was analyzed in microinjected clones and tumors derived from cells of these clones. In cells of the two non-tumorigenic clones, a telocentric chhromosome 1 (t1) was specifically involved in translocations with other chromosomes or chromosome fragments. In all tumor cells obtained from nude mice, a supernumerary piece or a whole biarmed chromosome 14 (b14) was specifically found. The results suggest that the t1 chromosome bears the gene which controls in vitro transformation and that the additional genetic change, i.e. the extra piece of b14 chromosome, was required for tumor formation in vivo.