This article is from the WSSF 2006 AFRMA Rat & Mouse Tales news-magazine.

By Carmen Jane Booth, D.V.M., Ph.D.

Karen Robbins
Q This subject came up at our last Board Meeting. One of our new members was asking about a vaccine for Mycoplasma, what’s involved, why there isn’t one, how to go about getting one, etc. There was a German group that was trying to get a vaccine developed in 2004 www.rattenzauber.de and has a page on their web site [http://rattenzauber.de/myco-neu.html] telling about what they were trying to do.

One thought that was suggested at the meeting was the rats may need the vaccine only once, become Myco free, then all of their kids will be Myco free and not need a vaccine, and therefore drug companies wouldn’t want to develop a vaccine that would be needed only short term. Would this be true?

Another suggestion was since the labs came up with c-section/barrier raised animals, they bypassed the need for a vaccine.

Other thoughts were that even though rats are more popular now than 20–30 years ago and more people are taking them to the vet, still not enough are taking them to the vet when they get sick so how many people would get the vaccine if there was one. Since there are breeders that have resistant rats (carry the disease but remain healthy throughout their life), then people should be getting their rats from these breeders rather than pet stores and rescues where the chance of getting sick rats is almost 100%.

This member wants to send out a questionnaire asking if people would be interested in getting a vaccine developed and if so, would they participate financially and then get their rats vaccinated if developed. She has a couple vets she would like to contact to see if they would participate. She said there is a vaccine for Myco in cattle and was wondering if this could be used in rats. Any thoughts?

A Regarding Mycoplasma Vaccine Development. This is a very interesting question and I will try and address each issue presented. Mycoplasma pulmonis is ubiquitous in non-laboratory pet rats, wild rodents, and is one of the most common causes of illness in pet rats as they age. It is correct that laboratory colonies have eliminated most diseases by embryo transfer and cesarian derivation; however, there must be constant vigilance because of the potential exposure of disease from wild rodents. No matter how secure facilities are, diseases have a way of getting into clean colonies either by wild rodents or transmission by the people who work with the animals. The amount of time and energy spent trying to keep a colony free of disease and screening for diseases is immense.

In laboratory colonies, a vaccine for mycoplasma or any of the rodent diseases would primarily be useful in valuable breeding colonies where the strains of rats or mice do not exist elsewhere. Unfortunately, because of the expense involved in the development of vaccines, you have to have a large market to absorb the high cost of development once the drug came to market. The other issue is that if they did develop a vaccine that was a single use, there would be no sustained market share. Realistically, for a drug company to be willing to go to the expense of developing and producing a vaccine, there has to be a financial incentive.

For development via a university, the costs are still high. For example, an investigator I know is trying to get funding to develop a vaccine against one of the mouse viruses from the National Institute of Health. The direct costs are $250,000 per year for 5 years and the indirect costs that the university he works at charges for facility fees, etc., on top of the direct fees, are an additional 70%. Thus, for 5 years of funded research, the total cost would be around 2.1 million dollars. In the current political climate with the war, federal research funding has declined markedly. The costs in industry are typically higher than those of a university.

From a biological standpoint, immunity would probably not be life long and both adults and offspring would require vaccination. Part of the problem is that there are other respiratory diseases that would also have to be addressed. This is the situation with cattle. Vaccination against Mycoplasma alone without vaccination or treatment for the other respiratory diseases is not as effective in preventing respiratory problems.

Lastly, there have been some papers published where investigatory are trying to develop a mucosal vaccine to use against the mycoplasma that causes disease in swine. They are using mice as their model and perhaps if they are eventually successful, there can be development of a vaccine against Mycoplasma pulmonis for rats.

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