On more than one occasion, Fawkes, youknowwho, Godric, and I have discussed in depth the scientific aspects of lycanthropy. Just another bit of proof of our nerdieness, I guess.
Anyway, one of our discussions has centered on whether lycanthropy is a virus or a genetic mutation. When a person is attacked and bit by a werewolf, does a virus attack their body or do their genes somehow get mutated? Or is it a combination of both and it's a virus that mutates genes?
In the Harry Potter books, the evidence of how lycanthropy is transmitted is evidence for viral. The fact that it is passed through bites shows that it's transmitted through blood or saliva. There are many viruses in the Muggle world that are transmitted through bodily fluids such as blood and saliva. HIV, for example.
However, the fact that Remus was so worried about passing on his lycanthropy to his child is evidence towards genetic. I imagine that Healers have a way of finding out whether a person's genes are changed when bitten. After all, doctors have mapped the human genome and have ways of finding out whether a person has a certain genetic disease. Therefore, it would make sense that Healers could figure out if Remus had a 'lycanthropy' gene. Since his parents searched for cures for lycanthropy, I think it's a fair assumption that at some point, a Healer figured out whether it was genetic. Remus's worries would make more sense if lycanthropy was genetic than viral.
If lycanthropy was a virus, Remus would not have been able to pass it on to Teddy. Viruses in the Muggle world can be passed from mother to unborn child, but not from father to unborn child. Anything the father gives the child must be in his genetic makeup. A virus could be passed from father to mother during the act of making a child, and then passed from mother to unborn child. But, we know from the Harry Potter books that Remus did not give Tonks lycanthropy.
If it is indeed genetic, then it would make sense for it to be recessive. Therefore, Tonks's non-lycanthropy gene would overcome Remus's lycanthropy gene. However, Teddy would be a carrier for lycanthropy. That has made me wonder if he and Victoire (who an argument could be made for also carrying the lycanthropy gene since her father was bitten by an untransformed Greyback) could possibly have a child who is a werewolf.
Then there are viruses that affect DNA structure itself. If lycanthropy were such a virus, though, it would have to affect the reproductive cells. Cancer, for example, is a virus that affects DNA structure of certain cells. But, if a person with cancer reproduces, their child is not born with cancer.
What does everyone think?