Nonsegmented negative-strand RNA viruses: Genetics and manipulation of viral genomes

Protocols to recover negative-strand RNA viruses entirely from cDNA have be en established in recent years, opening up this virus group to the detailed analysis of molecular genetics and virus biology. The unique gene-expressi on strategy of nonsegmented negative-strand RNA viruses, which involves rep lication of ribonucleoprotein complexes and sequential synthesis of free mR NAs, has also allowed the use of these viruses to express heterologous sequ ences. There are advantages in terms of easy manipulation of constructs, hi gh capacity for foreign sequences, genetically stable expression, and the p ossibility of adjusting expression levels. Fascinating prospects for biomed ical applications and transient gene therapy are offered by chimeric virus vectors carrying novel envelope protein genes and targeted to defined host cells.