Cloning and Characterization of the Acidic Ribosomal Protein P2 ofCryptosporidium parvum, a New 17-Kilodalton Antigen

Abstract

Cryptosporidium infection is commonly observed among children and immunocompromised individuals in developing countries, but large-scale outbreaks of disease among adults have not been reported. In contrast, outbreaks of cryptosporidiosis in the United States and Canada are increasingly common among patients of all ages. Thus, it seems likely that residents of regions where Cryptosporidium is highly endemic acquire some level of immunity, while residents of the developed world do not. A new immunodominant Cryptosporidium parvum antigen in the 15-to 17-kDa size range was identified as the Cryptosporidium parvum 60S acidic ribosomal protein P2 (CpP2). We developed a recombinant protein-based enzyme-linked immunosorbent assay for serologic population surveillance for antibodies that was 89% sensitive and 92% specific relative to the results of the large-format Western blot assay. The human IgG response is directed almost exclusively toward the highly conserved, carboxy-terminal 15 amino acids of the protein. Although IgG antibody cross-reactivity was documented with sera from patients with acute babesiosis, the development of an anti-CpP2 antibody response in our Peru study population correlated better with Cryptosporidium infection than with infection by any other parasitic protozoan. In Haiti, the prevalence of antibodies to CpP2 plateaus at 11 to 20 years of age. Because anti-CpP2 IgG antibodies were found only among residents of countries in the developing world where Cryptosporidium infection occurs early and often, we propose that this response may be a proxy for the intensity of infection and for acquired immunity.

Evaluation of DNA encoding acidic ribosomal protein P2 of Cryptosporidium parvum as a potential vaccine candidate for cryptosporidiosis

“…Endotoxin was removed using Detoxi-Gel Endotoxin Removing Columns (Thermo Scientific, Rockford, IL). rCpP2 was also expressed as a 6xHis fusion protein in pQE81 vector (Qiagen, Valencia, CA) using E. coli DH5α cells (Invitrogen, Carlsbad, CA) and purified as previously described (18). …”

“…The newly characterized CpP2 antigen has a molecular mass in the range of 17-kDa but is distinct from the C. parvum 17-kDa antigen family (18). All three acidic ribosomal proteins (P1, P0, and P2) from C. parvum react with sera from infected individuals; CpP2 in particular, is highly immunogenic, reacting with ~70% of sera from infected individuals from developing countries (18).…”

“…All three acidic ribosomal proteins (P1, P0, and P2) from C. parvum react with sera from infected individuals; CpP2 in particular, is highly immunogenic, reacting with ~70% of sera from infected individuals from developing countries (18). In highly endemic areas such as Haiti, individuals who had a strong anti-CpP2 antibody response were also antibody positive for the 27-kDa antigen, suggesting a role for the antigen in the generation of immune responses against C. parvum.…”

Treatment of Cryptosporidiosis

“…Administration of a DNA vaccine encoding C. parvum Cp15 and Cp23 resulted in induction of Th1 immune response and increased resistance to infection (Wang et al 2010). Evaluation of a DNA vaccine comprised of P2 (CpP2), an important immunodominant marker in C. parvum infection (Priest et al 2010), showed that CpP2-DNA followed with P2 protein (prime-boost), significantly increase antibody production over immunization with just the protein or CpP2-DNA alone. When challenged, reduction in oocysts production was not statistically significant, although a trend in reduction of infection was observed in the CpP2-DNA-immunized mice (Benitez et al 2011).…”

Systemic and Mucosal Immune Responses to Cryptosporidium—Vaccine Development

“…These modifications may be necessary for the function and immunogenic potential of the protein; and therefore, are important to consider when designing a screen for Cryptosporidium antigens. A phage-display C. parvum cDNA library was used to identify the surface antigen Cp12 and the immunodominant acidic ribosome protein P2 (110,111). Zhang and colleagues recently utilized a cell-free ribosome display platform to screen a C. parvum cDNA library for proteins that could adhere to IECs (112).…”