Vaccination against fungal diseases: lessons from Candida albicans

Abstract

The advances in medicine have achieved great benefits by improving or even eliminating various debilitating diseases or malignancies, expanding life expectancy. However, it has also originated the development of a compromised population susceptible to opportunistic diseases. A global major concern is the emergence and spread of life-threatening invasive infections in immunocompromised patients, in which the opportunistic fungal infections have greatly increased in the last decades. The high mortality rates associated with these infections, which remain as high as 40%, are due to the limited therapeutic options and the emergence of drug-resistant fungi, but also due to the lack of efficient early diagnosis. Consequently, these facts led to the opinion that new approaches are needed to improve the outcome of these patients, such as immunopreventive strategies that could even be combined with standard antifungal treatment. In view of the proven effectiveness of various antibacterial and antiviral vaccines in preventing the respective diseases, several works have been developed to induce protective immunity against fungal infections as well. The better understanding of how the immune system works against fungal pathogens has made possible to explore immunomodulatory strategies that can protect both immunocompetent and immunocompromised hosts and generate memory. Recently, two fungal vaccines against Candida have advanced through clinical trials. However, there are still many challenges in the development of an efficient vaccine against invasive fungal infections. We will provide an update on the progress made in immunization against fungal infections, reviewing host-fungi interactions, antigens, and adjuvants exploited in vaccine strategies, and discuss concerns that need to be overcome to further advance in the area of fungal vaccines.