Divalent Cp15-23 vaccine enhances immune responses and protection against Cryptosporidium parvum infection.

Cryptosporidiosis, caused by Cryptosporidium parvum, is life-threatening in individuals with compromised immune systems and a common serious primary cause of outbreaks of diarrhoea in newborn calves and goats. To date, no specific or effective therapy for cryptosporidiosis has been developed. There have been increasing efforts geared towards development of vaccines to control the disease. We have generated a divalent peptide vaccine candidate utilizing the Cp23 and Cp15 surface proteins of sporozoite of C. parvum that have been reported to be protective individually in certain animal models. We demonstrate that our vaccine candidate induced greater CD4(+) T cell, comparable CD8(+) T cell, significant Th1 cytokine and antibody responses against C. parvum in vaccinated mice in a direct comparison with the crude extract and single valent Cp23 vaccine and conferred partial protection against challenge of C. parvum. The study indicates that the fusion Cp15-23 vaccine protein is the better vaccine candidate and warrants further preclinical development for prevention of cryptosporidiosis.