Small dense LDL-cholesterol determined by a simple precipitation assay for screening familial combined hyperlipidemia.

Familial combined hyperlipidemia (FCHL), the most prevalent genetic hyperlipidemia, is associated with a several-fold increased risk of cardiovascular events. In spite of its prevalence and risk, no method has been developed to diagnose FCHL using conventional lipid markers. In an earlier study, our group established a simple precipitation assay for small dense low density-lipoprotein-cholesterol (sd-LDL-C) directly in serum. We conducted the present study to examine whether sd-LDL-C serves as a useful diagnostic marker for FCHL. When subjects (n=1661, M/F=1183/478) were stratified into normolipidemia, hypercholesterolemia, hypertriglyceridemia, and combined hyperlipidemia (CHL) groups, sd-LDL-C was higher in the CHL group than in the other groups, and higher in FCHL cases with family histories of hyperlipidemia than in CHL cases without family histories. FCHL is characterized by increased apolipoprotein (apo) B and small-sized LDL. Ninety-four percent of the subjects with both hyperapoB (>120mg/dl) and small-LDL (diameter <25.5nm) were classified into the top quartile of sd-LDL-C (>33mg/dl). These results suggest that sd-LDL-C determined by the simple precipitation method is useful for screening FCHL in large populations. However, the number of females included in the study is small, making it difficult to draw conclusions especially in females.

Genetic and antigenic diversity among noroviruses.

Human norovirus (NoV) strains cause a considerable number of outbreaks of gastroenteritis worldwide. Based on their capsid gene (VP1) sequence, human NoV strains can be grouped into two genogroups (GI and GII) and at least 14 GI and 17 GII genotypes (GI/1-14 and GII/1-17). Human NoV strains cannot be propagated in cell-culture systems, but expression of recombinant VP1 in insect cells results in the formation of virus-like particles (VLPs). In order to understand NoV antigenic relationships better, cross-reactivity among 26 different NoV VLPs was analysed. Phylogenetic analyses grouped these NoV strains into six GI and 12 GII genotypes. An antibody ELISA using polyclonal antisera raised against these VLPs was used to determine cross-reactivity. Antisera reacted strongly with homologous VLPs; however, a number of novel cross-reactivities among different genotypes was observed. For example, GI/11 antiserum showed a broad-range cross-reactivity, detecting two GI and 10 GII genotypes. Likewise, GII/1, GII/10 and GII/12 antisera showed a broad-range cross-reactivity, detecting several other distinct GII genotypes. Alignment of VP1 amino acid sequences suggested that these broad-range cross-reactivities were due to conserved amino acid residues located within the shell and/or P1-1 domains. However, unusual cross-reactivities among different GII/3 antisera were found, with the results indicating that both conserved amino acid residues and VP1 secondary structures influence antigenicity.

Expression and antigenicity of virus-like particles of norovirus and their application for detection of noroviruses in stool samples.

Human noroviruses (NoVs), members of the genus Norovirus in the family Caliciviridae, are the leading agents of nonbacterial acute gastroenteritis worldwide. Human NoVs are currently divided into at least two genogroups, genogroup I (GI) and genogroup II (GII), each of which contains at least 14 and 17 genotypes. To explore the genetic and antigenic relationship among NoVs, we expressed the capsid protein of four genetically distinct NoVs, the GI/3 Kashiwa645 virus, the GII/3 Sanbu809 virus, the GII/5 Ichikawa754 virus, and the GII/7 Osaka10-25 virus in baculovirus expression system. An antigen enzyme-linked immunosorbent assay (ELISA) with hyperimmune serum against the four recombinant capsid proteins and characterized previously three capsid proteins derived from GI/1, GI/4, and GII/12 was developed to detect the NoVs antigen in stools. The antigen ELISA was highly specific to the homotypic strains, allowing assignment of a strain to a Norovirus genetic cluster within a genogroup.