Rapid clearance of intranasally administered DNA from rat tissues

The cold-adapted (ca) live attenuated influenza vaccine (LAIV) strains are manufactured in embryonated hens' eggs. Recently, a clonal isolate from Madin Darby Canine Kidney (MDCK) cells was derived and characterized to assess its utility as a potential cell substrate for the manufacturing of LAIV [1]. Since MDCK cells are a transformed continuous cell line [2], and low levels of residual cellular components (DNA and protein) are found in the intermediates and final filled vaccine, we sought to characterize the uptake and clearance of MDCK DNA from tissues in order to assess theoretical risks associated with manufacturing LAIV in MDCK cell culture. In order to address this concern, MDCK DNA uptake and clearance studies were performed in Sprague Dawley rats. DNA extracted from MDCK Master Cell Bank (MCB) cells was administered via an intranasal (IN) or intramuscular (IM) route. Tissue distribution and clearance of MDCK DNA were then examined in fourteen selected tissue types at selected time points post-administration using a quantitative PCR assay specific for canine (SINE) DNA. Results from these studies demonstrate that the uptake and clearance of MDCK DNA from tissues vary depending on the route of administration. When DNA was administered intranasally, as compared to intramuscularly, detectable DNA levels were lower at all time points. Thus, the intranasal route of vaccine administration appears to reduce potential risk associated with residual host cell DNA that may be present in cell culture produced final vaccine products.