A vaccine for Valley Fever appears to have major promising results. Not for people, but for dogs. The delta-CPS1 vaccine was originally derived from an infection that attacked maize, but now is useful for a “live” vaccine using genetically modified Coccidioides spores that are not able to cause the symptoms that characterize Valley Fever. Since dogs are so severely affected by Valley Fever this may be welcome news for our canine companions.
A possible canine vaccine for Valley fever took one giant step closer to becoming a reality thanks to a University of Arizona College of Medicine – Tucson-led study that showed the vaccine provided a high level of protection against Coccidioides posadasii, a fungus that causes Valley fever. The development of a potential canine vaccine serves as a positive harbinger of a human vaccine.
Valley fever, also known as coccidioidomycosis, is primarily a disease of the lungs caused by the inhalation of airborne particles of the fungus Coccidioides, which is found in the southwestern U.S. and northwestern Mexico. Dogs are very susceptible to Valley fever, and it is estimated that Valley fever costs Arizona dog owners at least $60 million per year.
Noteworthy in the study was the fact that one dose was not sufficient to stop dissemination. To work most effectively, two doses of the vaccine will be needed, not unlike the mRNA COVID-19 vaccines.
With two doses this vaccine was highly protective against dissemination and other symptoms.
In fact, with two doses the signs of infection could only be found due to the extremely close examination that occurred in the vaccine study. For example, the measure of fungal “colony forming units” in the lungs were less than 100 microscopic spores. It was said this level of infection would not even have been noticed at all by a veterinarian.
Since this was an eight week study, it is unknown how durable this immunity will be over the long term.
Also of interest is that…
- No antifungal vaccine has been approved by government medical authorities
- It is unknown whether the deletion of the Delta-CPS1 gene might result in “gain-of-function” among the vaccinated organisms, creating different symptoms (Van Dyke, et al.)
- The concept of using a live vaccine in humans may face additional regulatory hurdles, which is part of the reason why the live attenuated vaccine was developed for dogs first.
- The vaccine has not yet been approved for veterinary use and distribution at this time.
For more information:
The University of Arizona describes the canine Valley Fever vaccine work, and is the source of the primary quotations and images here
The journal Vaccine made the full study available online
Van Dyke MCC, Thompson GR, Galgiani JN, Barker BM. The Rise of Coccidioides: Forces Against the Dust Devil Unleashed. Front Immunol. 2019 Sep 11;10:2188.
A history of Valley Fever drug and vaccine research that included information about Delta-CPS1