Blastocysts exhibit preferential uptake of DNA fragments from the E6-E7 conserved region of the human papillomavirus.

The objective of the study was to determine if embryos at the blastocyst stage differentially took up exogenous human papillomavirus (HPV) DNA derived from the different HPV types and to determine whether the capture process was active or passive. In vivo fertilized mouse embryos were cultured to the blastocyst stage in vitro. The mouse blastocysts were incubated for 2 hr in the presence of a mixture of exogenous DNA fragments derived from HPV types 6b, 11, 16, and 18. The blastocysts were rigorously washed and analyzed for differential uptake of HPV gene sequences using the polymerase chain reaction (PCR) and polyacrylamide gel electrophoresis. PCR analysis detected HPV type 18 in only 40% of the blastocyst groups while detecting the other HPV types in 100% of the blastocysts. The negative control group did not show HPV DNA after PCR ruling out possible PCR artifacts. Formalin-fixed blastocysts also showed uptake of HPV DNA. In conclusion, the data suggest a role for embryos as passive vectors for foreign DNA and that the degree of DNA uptake varies with different types of HPV DNA.