Virus was produced by the Baylor/Texas Children's Hospital GLP facility. The titer 
was 1.6 x 10 11 particles/ml as determined by optical density. The vector was tested for in 
vitro and in vivo toxicity, tk function tests, replication competence, and contamination. 
Before virus injections MRs were performed on all baboons. Pre-op samples of serum, 
sperm, urine, and stool were collected and tested wild-type adenovirus. Serum was tested 
for neutralizing antibodies to wild-type adenovirus. 
Three treatment groups were established: 
Group 1 - Moderate dose ADV/RSV-tk, with GCV. 6-week survival. A moderate dose 
of ADV/RSV-tk (1.5 x 10 9 particles in 10 ml PBS with 10% glycerol) was injected into the 
centrum semiovale of a 16.3 year-old, cycling female and a 17.5 year-old male baboon. 
Beginning the following day they began treatment with 10 mg/kg of GCV twice daily for 14 
days. Samples were taken at 2 and 7 days post-injection for analysis for virus and anti- 
adenoviral antibodies. At 3 weeks following virus injection the animals were MR imaged with 
gadolinium enhancement. At approximately 6 weeks following virus injection plasma, serum, 
urine, stool and sperm samples were again collected for analysis for the presence of 
shedded virus and the presence of antibodies to adenovirus, the brains were imaged with 
gadolinium enhancement, and the animals were necropsied. 
Gross examination of the brains showed no abnormalities. Specifically, no necrotic 
cavities, mass effect, hemorrhage, or subarachnoid clouding were seen. The brains were 
sampled extensively for microscopic evidence of abnormality, and in both, small areas of 
macrophage infiltration and mild perivascular lymphocytic cuffing were present in the 
centrum semiovale of the right hemisphere. No cuffing was present beyond the right 
hemisphere, and no white matter edema was present. No leptomeningitis was evident. No 
necrosis or viral inclusions were seen. The choroid plexus and ependyma were intact. 
No systemic pathology was seen with the exception of focal hepatic lymphocytic 
infiltrates without necrosis in one animal. The systemic examination in the other animal was 
normal. 
Group 2 - High dose ADV/RSV-tk. with GCV. 3-week survival. At the FDA's explicit 
request two baboons were treated with a high dose of ADV/RSV-tk and GCV. ADV/RSV-tk 
(3 x 10 10 particles in 200 ml PBS with 10% glycerol) into the centrum semiovale of a 16 
year-old, cycling female and a 11 year-old male baboon. The following day the animals 
began treatment with 10 mg/kg of GCV twice daily for 14 days via the tether system. At 2 
days post-injection and at 1 week post-injection plasma, serum, urine, stool and sperm 
samples were collected for analysis for the presence of shedded virus and the presence of 
antibodies to adenovirus. We had planned that if no virus was found, the animals would be 
imaged with gadolinium enhancement at approximately 3 weeks following virus injection 
necropsied the next day. The male baboon died 5 days after virus injection. 
These animals died or were euthanized at 5 and 10 days following vector injection and 
initiation of GCV treatment. In both there was a 1.5 to 1.8 cm area of liquefactive necrosis 
at the injection site. These necrotic masses exerted mass effect. Histopathological 
examination revealed acute inflammation characterized by polymorphonuclear cells and 
lymphocytes admixed with eosinophilic liquefactive necrosis of the centrum semiovale. 
Radiating from the necrotic mass was cerebral edema evinced by white matter spongiosis. 
Intense lymphocytic perivascular cuffing was seen up to 1 .5 cm away from the injection 
cavity in the right hemisphere. Coagulative necrosis was seen transmurally in vessels 
Recombinant DNA Research, Volume 20 
