Cryptosporidium hominis-specific nature of Chro.50011. A. Insertion of ~4,860 bp containing the Chro.50011 gene at the 3′ end of chromosome 3 in C. hominis. B. Confirmation of the absence of the ortholog of Chro.50011 in four specimens of C. parvum by PCR analysis of three regions of the Chro.50011 gene. The faint band in PCR analysis of the 3′ end of the gene in C. parvum specimen 38416 produced a nucleotide sequence identical to Chro.50011 in C. hominis.