<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Feng, Xiaochuan</style></author><author><style face="normal" font="default" size="100%">Rich, Stephen M</style></author><author><style face="normal" font="default" size="100%">Tzipori, Saul</style></author><author><style face="normal" font="default" size="100%">Widmer, Giovanni</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Experimental evidence for genetic recombination in the opportunistic pathogen Cryptosporidium parvum.</style></title><secondary-title><style face="normal" font="default" size="100%">Mol Biochem Parasitol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Mol. Biochem. Parasitol.</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Animals</style></keyword><keyword><style  face="normal" font="default" size="100%">Conserved Sequence</style></keyword><keyword><style  face="normal" font="default" size="100%">Crosses, Genetic</style></keyword><keyword><style  face="normal" font="default" size="100%">Cryptosporidiosis</style></keyword><keyword><style  face="normal" font="default" size="100%">Cryptosporidium parvum</style></keyword><keyword><style  face="normal" font="default" size="100%">Deer</style></keyword><keyword><style  face="normal" font="default" size="100%">Female</style></keyword><keyword><style  face="normal" font="default" size="100%">Genotype</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">Male</style></keyword><keyword><style  face="normal" font="default" size="100%">Mice</style></keyword><keyword><style  face="normal" font="default" size="100%">Mice, Knockout</style></keyword><keyword><style  face="normal" font="default" size="100%">Microsatellite Repeats</style></keyword><keyword><style  face="normal" font="default" size="100%">Opportunistic Infections</style></keyword><keyword><style  face="normal" font="default" size="100%">Polymerase Chain Reaction</style></keyword><keyword><style  face="normal" font="default" size="100%">Recombination, Genetic</style></keyword><keyword><style  face="normal" font="default" size="100%">Survival Rate</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2002 Jan</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">119</style></volume><pages><style face="normal" font="default" size="100%">55-62</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Cryptosporidium parvum is an intracellular protozoan parasite causing intestinal malabsorption and diarrhea in humans. The infection is usually self-limiting, although persistent cryptosporidosis is observed in immunocompromised and malnourished individuals. As with other Apicomplexa, the life cycle of Cryptosporidium is thought to comprise a sexual phase, during which a motile microgamont fuses with a sessile macrogamont. The four sporozoites found within each oocyst (the infectious form excreted in the feces) are thought to be the product of a meiotic division taking place immediately following fertilization, but the existence of a meiotic cycle in this genus has not been tested experimentally. To substantiate the occurrence of meiotic recombination in this species, we performed a genetic cross between two distinct isolates of C. parvum co-infected in INF-gamma knockout mice. We found that mixed infections produced recombinant progeny characterized by multilocus genotypes comprising alleles inherited from each parental line. This observation represents the first demonstration of sexual recombination in this pathogen. Together with the occurrence of genetically heterogeneous infections, this finding suggests that outcrossing between genotypes may occur in nature. Experimental crosses among Cryptosporidium populations will facilitate mapping of clinically relevant genes, the delineation of Cryptosporidium species, and defining the taxonomical status of C. parvum subtypes and host-specific genotypes.</style></abstract><issue><style face="normal" font="default" size="100%">1</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/11755186?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Okhuysen, Pablo C</style></author><author><style face="normal" font="default" size="100%">Rich, Stephen M</style></author><author><style face="normal" font="default" size="100%">Chappell, Cynthia L</style></author><author><style face="normal" font="default" size="100%">Grimes, Kevin A</style></author><author><style face="normal" font="default" size="100%">Widmer, Giovanni</style></author><author><style face="normal" font="default" size="100%">Feng, Xiaochuan</style></author><author><style face="normal" font="default" size="100%">Tzipori, Saul</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Infectivity of a Cryptosporidium parvum isolate of cervine origin for healthy adults and interferon-gamma knockout mice.</style></title><secondary-title><style face="normal" font="default" size="100%">J Infect Dis</style></secondary-title><alt-title><style face="normal" font="default" size="100%">J. Infect. Dis.</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Adult</style></keyword><keyword><style  face="normal" font="default" size="100%">Animals</style></keyword><keyword><style  face="normal" font="default" size="100%">Body Weight</style></keyword><keyword><style  face="normal" font="default" size="100%">Cryptosporidiosis</style></keyword><keyword><style  face="normal" font="default" size="100%">Cryptosporidium parvum</style></keyword><keyword><style  face="normal" font="default" size="100%">Deer</style></keyword><keyword><style  face="normal" font="default" size="100%">Diarrhea</style></keyword><keyword><style  face="normal" font="default" size="100%">Disease Susceptibility</style></keyword><keyword><style  face="normal" font="default" size="100%">Female</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">Interferon-gamma</style></keyword><keyword><style  face="normal" font="default" size="100%">Mice</style></keyword><keyword><style  face="normal" font="default" size="100%">Mice, Knockout</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2002 May 1</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">185</style></volume><pages><style face="normal" font="default" size="100%">1320-5</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The infectivity of a Cryptosporidium parvum isolate of cervine origin (type 2, Moredun) propagated in calves was investigated simultaneously in healthy adult human volunteers and in interferon-gamma knockout (GKO) mice. After exposure to 100-3000 oocysts, 16 volunteers recorded, for a duration of 6 weeks, the number and form of stools that they passed and any symptoms that they experienced. Oocyst excretion was assessed by enzyme-linked immunosorbent assay and direct immunofluorescence assay. Eleven subjects (69%) became ill, and 8 subjects (50%) shed oocysts in stool. The median duration of illness was 169 h, and the median number of unformed stools passed was 24. The duration and intensity of symptoms were more severe than were those associated with previously studied isolates. The median infectious dose was estimated to be 300 oocysts for humans and 1 oocyst for the GKO mouse model. The Moredun isolate was more pathogenic than the reference GCH-1 isolate. The GKO mouse model of cryptosporidiosis is useful for discerning isolate-specific differences in pathogenicity.</style></abstract><issue><style face="normal" font="default" size="100%">9</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/12001050?dopt=Abstract</style></custom1></record></records></xml>