Identification of isolate-specific sporozoite proteins of Cryptosporidium parvum by two-dimensional gel electrophoresis.

Five isolates of Cryptosporidium parvum collected from human, horse, and calf sources were compared for differences in sporozoite protein patterns by using two-dimensional gel electrophoresis. Silver-stained two-dimensional gels contained over 300 protein spots from detergent-solubilized sporozoites. A distinguishing 106-kilodalton peptide that shifted in isoelectric point was detected in four of the five isolates. Computerized two-dimensional gel analysis was performed to obtain objective quantitation of the pI shift. Three of these four isolates could be differentiated from one other by the pI shift in this peptide. The fifth isolate was distinguished by the absence of the 106-kilodalton peptide and the presence of a 40-kilodalton peptide that was not observed in any other isolate.     

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

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.Cryptosporidium parvum and C. hominis are enteric protozoan parasites that commonly cause outbreaks of diarrheal disease in the developed world (for reviews, see references 24 and 26). All age groups are affected, and the disease is usually self-limiting in immunocompetent individuals (5, 13). Outbreaks have been linked to public water system treatment failures, recreational exposure to contaminated water, contamination of unpasteurized fresh-squeezed juices, and contamination of food products by infected food handlers (14, 28, 35, 37, 39, 58). In the developing world, where potential sources of food and water contamination are widespread, acute cryptosporidiosis is usually limited to young children and to immunocompromised populations (4, 5, 48, 50, 59). In a longitudinal serologic study of enteric parasites in Peru, we reported that repeated infection was common among young children and that Cryptosporidium-specific IgG antibody levels increased with age and with experience of infection (54). Large-scale outbreaks of overt illness among immunocompetent adults in these regions where cryptosporidiosis is highly endemic have not been reported. These observations suggest that some level of immunity to disease (although not necessarily to infection) may eventually develop upon repeated exposure to the parasite (20).In previous work (68), we noted that sera from individuals who live in Haiti often contain IgG antibodies to several C. parvum antigens, in addition to the immunodominant 27- and 17-kDa antigens. In the current work, we demonstrate that one of these novel antigens, located in the 17-kDa-molecular-mass range but distinct from the C. parvum 17-kDa antigen family (56), is the C. parvum acidic ribosomal protein P2 (CpP2). Several acidic ribosomal proteins (P0, P1, P2, or variants) have been described as prominent antigens in leishmaniasis (69, 70), Chagas'' disease (32, 65, 67), malaria (10), Brucella abortus infection (6), Babesia bovis infection (12), and systemic lupus erythematosus (SLE) (16, 17, 62). In particular, ribosomal proteins P0 and P2 from Leishmania spp., Plasmodium falciparum, and Trypanosoma cruzi have been reported to be immunostimulatory, as sera from infected animals and humans recognize these antigens (10, 65, 66, 67,69, 70). Although the acidic ribosomal proteins are classically associated with the cytoplasmic ribosomes, they have also been localized to the cell surface of some parasites. Chatterjee et al. (9) used antibody fluorescence to demonstrate the presence of the P0 protein on the surface of P. falciparum merozoites, and Sehgal et al. (63) used transiently transfected Toxoplasma gondii cells to demonstrate the translocation of tagged P0 to the parasite surface.Because of their surface localization and immunogenicity, it has been suggested that P proteins may be possible vaccine candidates. In recent reports, immunization with the P-domain peptide of ribosomal protein P0 provided protection against P. falciparum challenge (60), immunization with Babesia gibsoni P0 protein was cross-protective for infection with Babesia microti (73), and antibodies against Neospora caninum P0 inhibited infection with T. gondii in vitro (79). Furthermore, a Leishmania infantum ribosomal protein DNA vaccine conferred protective immunity against Leishmania major infection in mice (22). The strong anti-CpP2 antibody responses observed for most of the Haitians who were also antibody positive for the 27-kDa antigen suggest that the CpP2 antigen may play a role in the generation of immune responses against C. parvum in areas where it is highly endemic and, therefore, might be a potential vaccine target.     

Barriers to effective self-management in cardiac patients: The patient's experience

Objective

This paper identifies common obstacles impeding effective self-management among patients with heart disease and explores how for disadvantaged patients access barriers interfere with typical management challenges to undermine patients’ efforts to care for their illnesses.

Methods

We convened 33 focus group discussions with heart patients in 10 U.S. communities. Using content analysis, we identified and grouped the most common barriers that emerged in focus group discussions.

Results

We identified nine major themes reflecting issues related to patients’ ability to care for and manage their heart conditions. We grouped the themes into three domains of interest: (1) barriers that interfere with getting necessary services, (2) barriers that impede the monitoring and management of a heart condition on a daily basis, and (3) supports that enable self-management and improve care.

Conclusion

For disadvantaged populations, typical problems associated with self-management of a heart condition are aggravated by substantial obstacles to accessing care.

Practice implications

Ensuring disadvantaged patients with chronic heart conditions are linked to formal systems of care, such as cardiac rehabilitation programs, could better develop patients’ self-management skills, reduce barriers to receiving care and improve the overall health outcomes of these patients.