Recombinant DNA Advisory Committee - 12/^4/92 
the two most dominant cytotoxic T lymphocyte (CTL) antigens. Therefore, the marked 
production of CTL in response to the vector is very unlikely. There is a gene within the 
Ela region that is required to terminate protein synthesis. Host protein synthesis is 
inhibited by preventing the host messenger RNA (mRNA) from being transported into 
the cytoplasm. Consequently, CFTR mRNA will continue to be expressed. 
Within the E3 region is a gene that codes for a 19 kilodalton (kd) glycoprotein (gp). 
The gp prevents Class I major histocompatibility complex (MHC) antigens from being 
transported to the cell surface, and it is critical for CTL recognition. When the gene 
coding for this gp is deleted, in vivo pathology is augmented. This increased response is 
due to the fact that the significant part of the disease is a product of the expression of 
early genes. Viral replication is unnecessary for disease manifestation; pathology is the 
result of the expression of early genes. 
Dr. Ginsberg responded to Dr. Parkman's question regarding the persistence of 
adenovirus in the host. Adenoviruses do not persist in infected epithelial cells, because 
these cells eventually die. Dead cells are shed by the host, not lysed. Although 
adenovirus DNA is capable of persisting in the lymph node, it is unlikely that DNA will 
exist anywhere other than the epithelial cells. 
Regarding possible recombination, it is very unlikely that a recombinant will result from 
an Ela wild-type gene and the CFTR gene, because the resulting construct would be too 
large to be assembled. 
Dr. Murray asked if other RAC members had questions for Dr. Ginsberg. Dr. Doi 
asked that if the DNA does not persist in epithelial cells, will the CFTR be present for 
only a short period of time? Dr. Ginsberg said that gene persistence will be a limiting 
factor. Dr. Schaechter asked if transfection of the CFTR gene would cause an increased 
turnover in these cells. Dr. Ginsberg responded that there would not be an increase in 
cell death; turnover will be based on the normal half-life of the epithelial cells. 
Dr. D. Miller asked if adenoviruses are lytic to cultured cells. Dr. Ginsberg noted that 
this statement is a universal misconception. Adenoviruses are not lytic. The only means 
of obtaining the virus from infected cells is to lyse the cell by another method. Dr. D. 
Miller asked about an appropriate assay for the detection of adenovirus helper. Dr. 
Ginsberg stated that HeLa and KB cells are the best choice for performing a plaque 
assay. Plaques will indicate the presence of dead cells that are killed by replication- 
competent adenovirus. 
Dr. Post asked if there is data regarding the enteric administration of an E3 minus 
adenovirus to humans. Has an E3 minus adenovirus ever been given to a human via the 
Recombinant DNA Research, Volume 16 
[553] 
