Issues to Consider in Using the TVA Technology

1. Selecting a tv-a isoform (tv-a 800 or tv-a 950):

When selecting an isoform for in vivo expression, there is no preferred isoform of tv-a.  Both tv-a 800 and tv-a 950 cDNAs have been used in transgenic and tissue culture work.  To date, tv-a 800 has been the isoform most frequently used in generating transgenic mice.

2. Experimental constraints on selecting a process for infection:

Producer cells can live in the mouse for a few days and can continue to produce new virus during this time.  However, there is a possibility that chicken cells may elicit a host immune response.

Culture supernatant is easier to obtain, but virus titer and volume are concerns and the presence of calf serum may cause immune reactions

Concentrated viruses may be preferred if the volume of infecting material needs to be limited (e.g. when infecting developing organs in embryos or newborns)

3. Possible immune responses against the virus and/or infected cells:

Infections are unlikely to cause immune rejections since viral proteins are minimally produced.  However, a mouse insert may be preferable over a human insert to avoid any possible response against the gene product of interest.