Biodistribution and toxicological safety of adenovirus type 5 and type 35 vectored vaccines against human immunodeficiency virus-1 (HIV-1), Ebola, or Marburg are similar despite differing adenovirus serotype vector, manufacturer's construct, or gene inserts

Abstract

The Vaccine Research Center has developed vaccine candidates for different diseases/infectious agents (including HIV-1, Ebola, and Marburg viruses) built on an adenovirus vector platform, based on adenovirus type 5 or 35. To support clinical development of each vaccine candidate, pre-clinical studies were performed in rabbits to determine where in the body they biodistribute and how rapidly they clear, and to screen for potential toxicities (intrinsic and immunotoxicities). The vaccines biodistribute only to spleen, liver (Ad5 only), and/or iliac lymph node (Ad35 only) and otherwise remain in the site of injection muscle and overlying subcutis. Though approximately 10(11) viral particles were inoculated, already by Day 9, all but 10(3) to 10(5) genome copies per mu g of DNA had cleared from the injection site muscle. By three months, the adenovector was cleared with, at most, a few animals retaining a small number of copies in the injection site, spleen (Ad5), or iliac lymph node (Ad35). This pattern of limited biodistribution and extensive clearance is consistent regardless of differences in adenovector type (Ad5 or 35), manufacturer's construct and production methods, or gene-insert. Repeated dose toxicology studies identified treatment-related toxicities confined primarily to the sites of injection, in certain clinical pathology parameters, and in body temperatures (Ad5 vectors) and food consumption immediately post-inoculation. Systemic reactogenicity and reactogenicity at the sites of injection demonstrated reversibility. These data demonstrate the safety and suitability for investigational human use of Ad5 or Ad35 adenovector-based vaccine candidates at doses of up to 2 x 10(11) given intramuscularly to prevent various infectious diseases.

Figures

FIG. 1

Biodistribution results. Box and whisker plots showing the copy numbers present in various tissues at SD9 and SD91/93 for control and treated animals in Studies A, B, and C. p-values are reported for comparisons between first and last time points in the treated groups, demonstrating clearance of vector from these tissues over the time course of the studies.

FIG. 2

Body temperatures in immediate post-vaccinal periods in Studies D, E, F, and G. Mean body temperatures are compared to gender-matched controls. Differences which were significant at the p ≤ 0.05 level are noted with an asterisk. Adjustments were not made to account for multiplicity, to more stringently detect potential safety signals. The groups compared are indicated by the lines over the bars. Error bars reflect the standard deviations. Time points marked with were taken 3 hr post-inoculation (hpi) on that study day.

FIG. 3

Food consumption in the immediate post-vaccinal periods in Studies D, E, F, and G. Mean food consumption was compared to gender-matched controls. Differences that were significant at the p <0.05 level are noted with an asterisk. Adjustments were not made to account for multiplicity, to more stringently detect potential safety signals. The groups compared are indicated by the lines over the bars. Error bars reflect the standard deviations. This parameter was not measured on study days when animals were fasted for blood draws.