Vaccine could protect against cancer caused by organ transplants
People who have received organ transplants are 250 times more likely to develop non-melanoma skin cancer than the normal population. The exact cause of this cancer is not known for sure but scientists say it is highly likely to be the human papillomavirus (HPV). New research using an uncommon African mouse suggests these suspicions are well-founded, and that a vaccine could be used to protect transplant patients when they are at their most vulnerable.
HPV infects the skin and is spread through close skin-to-skin contact. Infection is very common but usually causes no symptoms at all; up to 8 out of 10 people will be infected with the virus at some point in their lives, many without knowing. However, donor organ recipients must take drugs that suppress their immune system to avoid organ rejection. This can leave them open to serious infection by HPV, which causes painful skin lesions that can persist for many years. And in some cases these can turn cancerous.
To study HPV infection, researchers turned to an unusual and not often used lab mouse, the African multimammate mouse (Mastomys coucha). Like humans, this species of mouse is naturally infected with papillomaviruses during early life and can later go on to develop symptoms such as warts and benign tumours in the skin.
The researchers produced experimental vaccines using virus-like particles, which are essentially empty viral shells without any infectious DNA. HPV vaccines already on market and routinely given to schoolgirls to protect against cervical cancer are also produced using this method.
When these vaccines were given to the mice, none went on to develop symptoms of infection or skin cancer. Crucially for transplant patients, the protective effect was still seen when the mice were given immunosuppressive drugs. This suggests that a vaccine administered before surgery could reduce or prevent the risk of HPV infection and the development of cancer in the recovering patient. More research will be needed, including clinical trials, to find out whether this is true.
This is the first time the African mouse has been used in HPV vaccine research and development. Vaccines already available for other HPV-linked cancers were developed primarily using cows, dogs and rabbits. The mouse could prove highly useful in future research and may even reduce the need for research on these other species.