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Tenacity of exogenous human papillomavirus DNA in sperm washing
J E Brossfield1, P J Chan, W C Patton
1Department of Gynecology and Obstetrics, Loma Linda University School of Medicine, California 92350, USA.
Purpose:
Sperm cells have been shown to take up exogenous DNA readily. The hypothesis was that sperm washing would remove exogenous viral DNA infecting sperm cells. The objective was to compare three types of sperm washing procedures for their capacity to remove exogenous human papillomavirus (HPV) DNA from infected sperm.
Methods:
Prewashed sperm were equally divided and sperm in one portion were exposed to L1 HPV DNA fragments for 30 min at 37 degrees C. Untreated washed sperm served as the control. After transfection, the sperm were washed by either centrifuge, two-layer Isolate colloid wash, or test-yolk buffer procedures. Sperm parameters were measured on a Hamilton Thorn HTM-C analyzer. Sperm DNA were extracted and polymerase chain reaction (PCR) was carried out targeting the L1 consensus gene of HPV and the designated sentinel gene, 17q21 spanning the D17S855 gene. Amplified products were analyzed in 2% agarose gel electrophoresis.
Results:
PCR analyses detected the consensus L1 HPV gene in sperm after they were processed through either of the three procedures. Controls were negative for the L1 gene. Extracted DNA were verified by PCR amplification of 17q21 spanning the D17S855 gene. Transfected sperm had higher percentages of total motility and progression compared with the control. Centrifuged, washed, transfected sperm exhibited a greater curvilinear velocity and hyperactivation.
Conclusions:
The data showed that washing would not remove exogenous HPV DNA from sperm cells. The viral DNA was tenaciously bound to the sperm, suggesting an internalization into the sperm. The viral DNA also increased the motility of the sperm by affecting the velocity and progression of the sperm, which suggested either an increase in metabolism, an enhancement of the calcium-regulated motility mechanism, or an artifact of PCR reagents. More studies are needed to elucidate the mechanism of DNA stimulated sperm motility.
Insights
Sperm washing procedures do not remove human papillomavirus (HPV) DNA from sperm cells. This viral DNA appears to bind tenaciously, potentially internalizing into sperm and enhancing motility.
Area of Science:
- Reproductive Biology
- Virology
- Molecular Biology
Background:
- Sperm cells can readily uptake exogenous DNA.
- The presence of viral DNA in sperm raises questions about its removal and potential effects.
Purpose of the Study:
- To evaluate the efficacy of three sperm washing procedures in removing exogenous human papillomavirus (HPV) DNA from infected sperm.
- To determine if sperm washing can eliminate viral DNA contamination.
Main Methods:
- Sperm were exposed to L1 HPV DNA fragments.
- Three washing procedures were tested: centrifugation, Isolate colloid wash, and test-yolk buffer.
- Sperm parameters were analyzed, and DNA was extracted for PCR to detect HPV L1 gene and a sentinel gene.
Main Results:
- All three sperm washing procedures failed to remove exogenous HPV DNA from sperm.
- HPV DNA was detected in sperm even after washing, indicating tenacious binding or internalization.
- Transfected sperm showed increased motility, including higher velocity and hyperactivation.
Conclusions:
- Standard sperm washing methods are ineffective in removing exogenous HPV DNA from sperm.
- Viral DNA may be internalized by sperm and can enhance sperm motility.
- Further research is required to understand the mechanism of DNA-induced sperm motility changes.