| Background: Noroviruses (NVs), previously known as Norwalk-like viruses (NLV) or small round structured viruses (SRSV), belong to the Norovirus genus of Caliciviridae family. NVs have been recognized as the most important cause of non-bacterial epidemics of acute gastroenteritis since the application of molecular diagnostic methods in epidemiology studies of diarrhea diseases in different countries following the cloning of the prototype Norwalk virus in 1990. In developed countries such as the United States of America and many European countries, NVs have been found to be the most important cause of non-bacterial outbreaks of acute gastroenteritis. Such outbreaks can occur in variety settings and affecting all ages, including child care centers, schools, restaurants, summer camps, hospitals, nursing homes, cruise ships and military settings. NV-outbreaks have been particularly considered as a serious public health problem in nursing homes for the elderly, on board of large commercial cruise ships and in military camps and battleships during deployment and wartime.Fang zhao-yin et al firstly reported the NVs in Henan at 1995 in our country, and then Fang zhao-yin and Qian yuan et al found that NVs infection exists but not SVs in Beijing and Chuangchun, and the detect rate was about 15%. Jing Yu et al found that NVs widely exists in North China by investigating the antibodies level of NVs in Beijing and Taiyuan. However, the NVs study in North China is still blank! That whether NVs exist in Guangzhou, and the antibodies level, or if the NVs exists, what about the gene-type? All this is urgent task to fulfill in North China. In addition, the relationship between the pathogenesis of NVs and the histo-blood type antigen now is hotspot in the pathogenesis region. While, there still isn't any study on this region in China.AIM: To explore whether the HuCVs infection exists in Guangzhou and the infection level and to determine if strain-specific host specificity occurs among students with different blood types.METHOD: Serum specimens were tested by an enzyme-linked immunosorbent assay (ELISA) for IgG against recombinant capsid antigens from three NVs (rNorwalk, rMX and r387). HuCVs were detected from the stool specimens by RT-PCR. The PCR products were cloned, transferred, and blasted with Genbank. Also nucleotide sequences homologous were compared with PHYLIP package, and the heredity anagenesis tree was protracted by Treeview.RESULT:1. The seroprevalence was 68.0%for rNV, 51.5% for rMX and 71.1 %for r387 in children.2. Serum specimens were tested by an enzyme-linked immunosorbent assay (ELISA) for IgG against recombinant capsid antigens from three NVs (rNorwalk, rMX and r387). Among 588 serum samples tested, the antibody prevalence was 88.9%, 54.1% and 90.0% for the three antigens respectively. There were significant differences of antibody prevalence between blood types for rMX (P < 0.05), in which the type O was the highest (62.5%) and the type B the lowest (49.1%). The average OD values of antibody against rNV and rMX were the lowest among students with type B than students with other types. The number of students who did not have an antibody against any of the three antigens was the highest among type B (6.9%) compared with other blood types (0.8-3.4%, P < 0.006).3. The antibody prevalence also varied with the home-town residency of the students before joined the military, with the highest in rural areas, lower in small towns or villages, and the lowest in large cities.4. HuCVs were detected from 18 stool specimens of 206 viral diarrhea (8.74%); all the HuCVs were confirmed as NVs.5. two strain: HuCV/NVG II 003/2003/CHN (32282), HuCV/NVG II-6-004/2003/CHN (32283) from selected 6 NVs strain was identified as thenew NVs sub-genotype.CONCLUSION: There exists sporadic and outbreak of NVs in Guangzhou, NVs infection were acquired when children in infancy, and the infection rate increases sharply with age. This study provides information not only...
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