Another molecule is capable of binding to and neutralizing interferon gamma. Many of the protein products of late genes funtion in the post-translational processing of other viral proteins which form the structural units of the core and envelope proteins. The first microscopically detectable virus product is the characteristic double membrane that accumulates in the factory regions. Highly processed and packaged genomic DNA accumulates in the factories and within 24 hours of infection, mature viral part icles can be seen by electron microscopy. It is the vast minority of mature enveloped virus that fuse with the host cell plasma membrane and are released from the cell.
Most virus remains associated with the cell.
It appears that these few extracellular virus are responsible for spread of the infection throughout the body. Although smallpox does not represent a threat to human health today, vaccinia virus is under intensive study in a great number of research laboratories around the world. Some 16 years ago, it was first proposed at a vaccine meeting at Cold Spring Harbour Laboratories that vaccinia could be used as a recombinant vaccine carrying cloned expressed genes encoding protective antigens from other currently significant human pathogens. Since that time, pox virus research has exploded and a number of highly successful clinical trials of recombinant vaccinia vaccines have been reported. We will be discussing this research in a later lecture on vaccines.