Prevalence and genetic diversity of human caliciviruses (HuCVs) in Mexicanchildren

Human caliciviruses (HuCVs) contain two genera: "Norwalk-like viruses" (NLV s) and "Sapporo-like viruses" (SLVs). The importance of the two genera as a cause of acute gastroenteritis of infants and children remains unknown. Be ginning in 1989, a birth cohort of children in Mexico was enrolled and moni tored for acute gastroenteritis. A subset of 115 diarrhea stool specimens f rom 76 children and 66 non-diarrhea stool specimens from 64 children was ex amined for HuCVs by RT-PCR by using a primer pair (p289/290) that detects b oth NLVs and SLVs. Twenty-two (19%) of the 115 diarrhea stool specimens and 5 (7%) of 66 non-diarrhea stool specimens produced RT-PCR products of expe cted size (319 bp for NLVs and 331 bp for SLVs). Twenty of the twenty-seven strains were cloned and sequenced. Pairwise sequence analysis showed that 9 (60%) and 6 (40%) of the 15 strains from the diarrhea stools were NLVs an d SLVs, respectively. The same proportions of NLVs (60%) and SLVs (40%) wer e observed in the non-diarrhea stools. Strains in the NLV genus could be fu rther divided into four clusters: Lordsdale, MxV, and HV and one potentiall y new cluster. Strains in the SLV genus could be divided into three cluster s: Sapporo/82, Lon/92, and a potentially new cluster. Strains from the Lord sdale cluster were the most common among these children. The findings of bo th genera and multiple clusters of HuCVs co-circulating and the identificat ion of new strains of HuCVs in the population justify the need for future s tudies of HuCVs in infants and children. (C) 2000 Wiley-Liss, Inc.