MJ. Welsh and A.E. Smith, RAC Application 
vehicle control, low dose virus (6 x 10 6 PFU), and high dose virus (8 x 10 7 PFU). Each 
group contained 9-12 animals. The doses expressed as particles per animal were low dose, 
3.5 x 10 11 and high dose 5 x 10 12 . The particle to PFU ratio of this preparation of virus 
was lower than usual; we noted aggregation upon purification of this preparation, perhaps 
because of the scale required for this preparation of virus. Two to four animals per virus 
dose level were evaluated at three time points: 1 day, 1 week, and 4 weeks. In this study, 
viral vector persistence and possible spread is being evaluated by the assessment of the 
presence of virus in numerous organs including lung, gut, heart, liver, spleen, kidney, brain 
and gonads. The presence of virus in the various tissues is being evaluated by CPE assay 
of tissue homogenates where possible and, where tissue homogenates interfere with such 
assays, indirect immunofluorescence detection of viral proteins is being used. Adenoviral 
antibody titer has been measured in peripheral blood and lung lavage samples. 
Additionally, lung lavage, peripheral blood and lung histology were evaluated as in the 
previous study. 
Results 
The first phase of this study is completed, and evaluation of the large number of samples is 
ongoing. In the peripheral blood, total leukocyte counts were, in general, within normal 
range. A mild to moderate leukopenia was observed in several animals of all three 
treatment groups at the 4 week time point. However, this leukopenia did not appear to be a 
dose-related phenomenon. The only consistent dose-related effect observed was a mild 
elevation in total leukocyte count in the 1 week animals which had received the high dose 
of virus. Blood leukocyte differential counts were also generally normal throughout the 
study. Several animals in each treatment group had a mildly elevated percentage of 
neutrophils at the 1 day time point. Again, this observation did not appear to be related to 
virus dose. Neutrophil percentages were within the normal range for all treatment groups at 
both 1 and 4 weeks. 
In the lung lavage samples, no dose-dependent alterations in either total leukocyte count or 
leukocyte differential were observed. A few animals from all groups at the 1 day time 
point showed a slightly elevated percentage of neutrophils, consistent with an instillation- 
associated mild inflammatory response. Lavage samples from animals at all time points 
and treatment groups also showed some level of erythrocytes, both free and within 
phagocytic cells. The cause of this observation is not clear, however, it does not appear to 
be treatment-related. The absence of dose-related adverse effects on the lungs was also 
confirmed by the lavage protein data. There were no dose- or time-related changes in lung 
lavage protein observed. Although two animals from the 1 week control group exhibited 
moderately elevated protein levels, all other 1 week animals had normal protein levels in 
the lavage fluid. The histological evaluation of the lungs was also consistent with the 
observations noted above. Specifically, no dose- or time-related changes in lung histology 
were observed; airway epithelium was intact and no focal or widespread inflammation was 
observed. 
The lung lavage samples from 1 day and 1 week, and fecal samples from 1 week time 
points of all three treatment groups have been tested for the presence of infectious viral 
particles. No infectious virions were detected. The one month lung tissue samples from all 
four of the high dose and lung lavage samples from two high dose animals have also been 
tested and again no infectious virions detected. Remaining lavage, lung tissue and fecal 
samples from other time points are currently being tested. 
A clear time and dose-dependent serum antibody response was detected in all the hamsters. 
It should be noted that as expressed as mass/kg these animals were treated with 
approximately 50,000 times the maximum human dose proposed in our study. Lung lavage 
Recombinant DNA Research, Volume 16 
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