Preclinical pharmacokinetics and biodistribution of human papillomavirus DNA vaccine delivered in human endogenous retrovirus envelope-coated baculovirus vector.

Purpose: Test pharmacokinetics and biodistribution of a human papillomavirus(HPV)16L1 DNA vaccine delivered in human endogenous retrovirus envelope protein (HERV)-expressing baculovirus (AcHERV) and those of naked plasmid vaccine.

Method: HPV16L1 gene was administrated as a naked plasmid or in AcHERV to mice via intravenous and intramuscular routes. HPV16L1 gene was extracted and assayed by quantitative real-time polymerase chain reaction, which was determined to have a detection limit of 50 copies/µg genomic DNA..

Results: Mean residence times of HPV16L1 in AcHERV were 4.8- and 272.2-fold higher than naked HPV16L1 DNA vaccines after intramuscular and intravenous administration, respectively. Naked HPV16L1 DNA levels 1 month after injection were >3 orders of magnitude lower in each tissue tested than AcHERV-delivered HPV16L1, which was retained in most tissues without specific tissue tropism. AcHERV-delivered HPV16L1 administered intramuscularly persisted at the injection sites. However, the levels of copy numbers in muscle were low (1,800/μg genomic DNA) after 1 month, and undetectable after 6 months.

Conclusions: HPV16L1 delivered via AcHERV resides longer in the body than HPV16L1 in naked form. The lack of tissue tropism ensures the safety of AcHERV vectors for further development.