They studied the semen of 73 men who were participating in a fertility programme and 22 men with no history of infertility who had given semen samples for reasons unconnected to fertility.
AAV is a common virus that is found in the genital tissues and infection usually takes place when a child is in the womb, during childhood, or young adulthood.
"We found that AAV DNA was rarely detected in normal semen but significantly more frequently present in the men with abnormal semen analysis," said Dr Jörg Schlehofer of the Angewandte Tumorvirologie at Deutsches Krebsforschungszentrum in Heidelberg.
AAV DNA was found in 28 out of the 73 (38%) of the men whose semen was abnormal but in only one out of the 22 (4.6%) of the men with normal semen. The researchers also analysed testis samples from 38 men participating in an ICSI** programme, whose semen contained no sperm. They wanted to see whether it was possible for sperm to be infected during maturation. Ten of the samples carried AAV DNA.
The research team said that further virological and molecular studies were required to assess whether AAV was a possible cause of infertility and whether it could also influence the outcome of assisted reproductive techniques. "It raises the issue, for example, of whether sperm cells used in ICSI or other reproductive techniques should be checked for AAV or other viruses prior to fertilisation. At the least, we think there should be research on the consequences of an infected sperm infecting an "innocent" egg."
*DNA of adeno-associated virus (AAV) in testicular tissue and in abnormal semen samples. Human Reproduction Vol. 16. No. 11. pp 2333-2337. K.Erles, V Rohde M Thaele, S Roth, L Edler, J Schlehofer. Deutsches Krebsforschungszentrum, Heidelberg, University of the Saarland, Homburg/Saar, Institut für Fortpflanzungsmedizin, Saabrücken.
Journal
Human Reproduction