Transient detection of E1‐containing adenovirus in saliva after the delivery of a first‐generation adenoviral vector to human parotid gland

Abstract

Radiation-induced salivary hypofunction is a common side-effect of treatment for head and neck cancers. Patients suffer significant morbidity and there is no suitable conventional therapy. We are conducting a Phase I clinical trial, using a first-generation serotype 5 adenoviral (Ad5) vector encoding human aquaporin-1 (AdhAQP1) to treat such patients. One week after the administration of AdhAQP1 to an enrolled, generally healthy patient, E1-containing adenovirus was detected in parotid saliva. The real-time quantitative polymerase chain reaction (PCR) was used to measure the Ad5 E1 gene and AdhAQP1 in saliva and serum. PCR and sequencing were used to characterize viral/vector DNA extracted from saliva. The presence of infectious adenovirus was assessed by the inoculation of A549 cells with aliquots of saliva. Serum Ad5 neutralizing antibodies were measured by the inhibition of 293-cell transduction with an Ad5 vector encoding luciferase. Multiple clinical evaluations were performed. On day 7 after AdhAQP1 delivery, low levels of the Ad5 E1 gene were detected in parotid saliva (82 copies/microl). In addition, significant levels of AdhAQP1 were also detected (1.5 x 10(3) copies/microl). The patient was asymptomatic and subsequent analysis of parotid saliva samples prior to day 7 and after day 7 until day 42 was negative for both virus and vector. No virus or vector was detected in serum at any time. Detailed PCR analyses of DNA extracted from the day 7 parotid saliva sample suggested the absence of a recombination event, and no infectious virus was found. The patient most likely had a latent Ad5 infection in the targeted parotid gland that was activated after gene transfer and was without clinical consequence.