Amino acid sequence alignments between the human group C/Bristol and the published porcine group C/Cowden VP6 proteins have revealed a region of extreme sequence divergence. We have been unable to confirm the nucleotide sequence of the Cowden VP6 gene corresponding to this region of divergence. Direct sequencing of a PCR-amplified cDNA pool has revealed a frame shift, and three nucleotide changes, within the published sequence of the porcine (Cowden) VP6 gene. The corrected sequence of the porcine protein revealed a closer homology with VP6 from the Bristol strain and two new human group C rotavirus isolates. Atypical rotaviruses have been detected in the feces of children living in Belém, Brazil, and Preston, U.K. Direct sequencing of PCR-amplified cDNA corresponding to the VP6 gene of one isolate from each location confirmed the presence of a group C rotavirus. The complete nucleotide sequences of the VP6 genes from the group C/Belém and C/Preston rotaviruses contained an open reading frame of 1185 nucleotides (395 amino acids; deduced M(r) 44,669 Da). The Belém VP6 gene demonstrated 97.9% nucleotide homology with the human group C/Bristol VP6 gene and 83.4% nucleotide homology (91.6% deduced amino acid homology) with the corrected porcine group C/Cowden sequence. The Preston VP6 gene demonstrated 99.6% nucleotide homology with the human group C/Bristol VP6 gene and 84.0% nucleotide homology (91.6% deduced amino acid homology) with the corrected porcine group C/Cowden sequence. Remarkably, the deduced amino acid sequence of the Brazilian strain was identical to that of the U.K. isolates.