Saul Tzipori (Tufts Cummings School of Veterinary Medicine, North Grafton, MA)

Saul Tzipori (Tufts Cummings School of Veterinary Medicine, North Grafton, MA). diarrheal disease worldwide, particularly in immunocompromised hosts such as patients with acquired immunodeficiency syndrome and malnourished children in developing countries.14Cryptosporidiosis is usually either asymptomatic or self-limiting in immunocompetent hosts. However, in immunocompromised individuals, the disease can be severe and chronically devastating. Additionally,Cryptosporidiuminfection in malnourished children in developing Mouse monoclonal to MYL3 countries may result in severe long-term sequelae, including developmental delays and growth stunting.1,57Nitazoxanide, the only drug approved by the United States Food and Drug Administration for treatment of individuals with cryptosporidiosis, is not effective in immunocompromised hosts,8and has not been extensively evaluated in children in developing countries. Although children in these countries are considered an essential group to target for vaccine development, 9there is currently no vaccine available for prevention of cryptosporidiosis. A major focus of study on cryptosporidiosis offers been the BML-277 recognition and characterization of surface-associated parasite proteins that mediate attachment and invasion, with the goal of BML-277 developing interventions such as vaccines to prevent these relationships.10,11Understanding the immune response to these proteins is definitely a key step in the identification of potential vaccine targets.11 It is well known that cell-mediated immune responses are essential for protection from and clearance ofCryptosporidiuminfection.11,12However, although antibody reactions againstCryptosporidiumassociated with safety from diarrhea have been reported in infected humans, it is not known whether these reactions are themselves protective or whether they are merely reflective of protective cell-mediated reactions.12 BML-277 TwoCryptosporidiumspp. cause most infections in humans.Cryptosporidium parvuminfects animals and humans, whereasC. hominisprimarily infects humans.13Although most human being infections, particularly in developing countries, are caused byC. hominis,13most studies possess usedC. parvumoocyst lysates or native or recombinantC. parvumproteins mainly because antigens to evaluate immune reactions. Previously, we investigated the systemic antibody response toCryptosporidiumin a matched casecontrol study of children less than five years of age who presented with diarrhea to the International Center for Diarrheal Disease Study, Bangladesh (ICDDR, B).14UsingC. parvumoocyst lysate as antigen for enzyme-linked immunosorbent assays (ELISAs), we found that serum IgM levels toC. parvumwere higher at demonstration in instances (children with diarrhea andCryptosporidiumdetected by stool microscopy) compared with settings (age-matched children with diarrhea but noCryptosporidiumdetected by microscopy), and that the IgG levels increased significantly in cases compared with the settings over a three week follow-up period.14However, the nature of specific antigens identified by serum samples from these children is not known. Subsequently, using polymerase chain reaction (PCR) restriction fragment size polymorphism analysis in the 18S ribosomal RNA (rRNA) locus, we identified thatCryptosporidiumwas recognized in feces in 7 of the settings and that most children with PCR-confirmed illness (90%) were infected withC. hominis.15 A number of studies possess reported dominant serum antibody responses to 1517-kD and 2327-kD groups ofC. parvumantigens inCryptosporidium-infected individuals.1621One of the 1517-kD group of antigens was subsequently identified to be gp15 (also called Cp17, 15/17-kD antigen or 17-kD antigen), an immunodominant surface antigen encoded by theCryptosporidium gp40/15(also known asgp60) gene, which we and others have cloned and characterized.2225The gp15 is the C-terminal proteolytic cleavage product of the precursor gp40/15 (also known as gp60) protein,22,23and is BML-277 linked to the surface membrane via a glycophosphatidyl innositol anchor.26,27The presence of pre-existing serum antibodies to gp15 was associated with protection from diarrhea and reduced oocyst shedding in naturally or experimentally infected human beings (reviewed by Borad and Ward11and Riggs12). In addition, gp15 induced interferon-mediated cellular reactions in previously infected humans. 28These findings show that gp15 induces humoral and cellular immune reactions that may be protecting in humans, and raise the probability that gp15 may be a putative vaccine candidate. Thegp40/15(gp60) gene encoding gp15 is definitely highly polymorphic amongC. hominisandC. parvumisolates.23,29Although most of the polymorphisms are clustered in the gp40 portion of the molecule, there are several single nucleotide (SNP) and single amino acid (SAAP) polymorphisms betweenC. BML-277 hominisandC. parvumgp15.29Polymorphisms within the gp40 region of thegp40/15(gp60) gene form the basis for subtyping ofCryptosporidiumspp. from humans and animals worldwide into at least 17 major subtype family members.13However, polymorphisms in the gp15 part of the molecule have not been extensively characterized in clinical samples. Knowledge of whether immune reactions to gp15 are cross-reactive or varieties and/or subtype-specific is vital if this antigen is to be considered as a vaccine candidate. The goals of this study were 1) to compare antibody reactions to gp15 fromC. hominisandC. parvuminC. hominis-infected children with diarrhea (instances) and in children.