Immunostimulatory principles from Chlorella pyrenoidosa--part 1: isolation and biological assessment in vitro.

Our proprietary preparation obtained by extraction of Chlorella pyrenoidosa cells, ONC-107 (Respondin), was recently found to selectively boost antibody response to the influenza vaccine in a human clinical trial. Respondin is a potent stimulator of mouse B cell proliferation and an activator of macrophages. Bioactivity-guided resolution concluded that Respondin is composed of a mixture of immunostimulatory principles of different chemical nature. A combination of size exclusion, anion exchange and hydrophobic interaction chromatography revealed that the bulk of the immunostimulatory activity resides in polysaccharide/protein complexes with molecular masses larger than 100 kDa that are composed primarily of galactose, rhamnose and arabinose.

Mutations in NPC1 highlight a conserved NPC1-specific cysteine-rich domain.

Niemann-Pick type II disease is an autosomal recessive disorder characterized by a defect in intracellular trafficking of sterols. We have determined the intron/exon boundaries of eight exons from the conserved 3' portion of NPC1, the gene associated with most cases of the disease. SSCP analyses were designed for these exons and were used to identify the majority of mutations in 13 apparently unrelated families. Thirteen mutations were found, accounting for 19 of the 26 alleles. These mutations included eight different missense mutations (including one reported by Greer et al. [1998]), one 4-bp and two 2-bp deletions that generate premature stop codons, and two intronic mutations that are predicted to alter splicing. Two of the missense mutations were present in predicted transmembrane (TM) domains. Clustering of these and other reported NPC1 mutations in the carboxy-terminal third of the protein indicates that screening of these exons, by means of the SSCP analyses reported here, will detect most mutations. The carboxy-terminal half of the Npc1 protein shares amino acid similarity with the TM domains of the morphogen receptor Patched, with the largest stretch of unrelated sequence lying between two putative TM spans. Alignment of this portion of the human Npc1 protein sequence with Npc1-related sequences from mouse, yeast, nematode, and a plant, Arabidopsis, revealed conserved cysteine residues that may coordinate the structure of this domain. That 7 of a total of 13 NPC1 missense mutations are concentrated in this single Npc1-specific domain suggests that integrity of this region is particularly critical for normal functioning of the protein.

Linkage disequilibrium mapping of the Nova Scotia variant of Niemann-Pick disease.

Niemann-Pick type D (NPD) disease is a severe degenerative disorder of the nervous system characterized by the accumulation of tissue cholesterol and sphingomyelin. Because of a founder effect, it is unusually common in southwestern Nova Scotia, Canada. We have confirmed that almost all patients from 20 affected sibships descended on both sides from a small group of Acadians who settled in this region in about the year 1767. Previously using classic linkage analysis of this large kindred, we defined the critical gene region to a 13-cM chromosome segment between D18S869 and D18S66. Seven ESTs have been positioned within this interval. Carstea et al. (Niemann Pick C disease gene: homology to mediators of cholesterol homeostasis. Science 1997: 277: 232-235) recently demonstrated that one of these ESTs is the Niemann-Pick type C (NPCI) gene, the gene disrupted in most patients with NPC disease, and we have shown that a G3097-->T mutation in the NPC1 gene is also responsible for NPD. Here we report the development of five new polymorphic microsatellite markers and the testing for complete linkage disequilibrium in our single large NPD kindred that allowed us to reduce the NPD critical region to a 1-cM (1.3-1.6 Mb) interval between D18S1398 and D18S1108. In contrast, Carstea et al., using classic linkage analysis, required more than 18 unrelated NPC families to reduce the NPC1 critical region to a 5-cM interval. Our work supports the finding that NPD is an allelic variant of NPC1, and illustrates the power of large kindreds, which are common in Atlantic Canada and other relatively isolated areas, for gene mapping and identification.

FISH mapping and inter-Alu fingerprinting define the YAC contig map around the centromeric region of human chromosome 18.

Previous reports concerning the location of D18S44 with respect to the centromere have been ambiguous. Also, it has not been possible, based on formerly reported markers, to show that contigs WC18.0 and WC18.1 overlap. However, the data presented here definitively show, using FISH technology, that D18S44 (located on WC18.0) maps to proximal 18q. Furthermore, inter-Alu fingerprinting shows a clear overlap between WC18.0 and WC18.1, thereby establishing a complete contig between D18S44 and markers from WC18.1.

The Nova Scotia (type D) form of Niemann-Pick disease is caused by a G3097-->T transversion in NPC1.

Niemann-Pick type D (NPD) disease is a progressive neurodegenerative disorder characterized by the accumulation of tissue cholesterol and sphingomyelin. This disorder is relatively common in southwestern Nova Scotia, because of a founder effect. Our previous studies, using classic linkage analysis of this large extended kindred, defined the critical gene region to a 13-cM chromosome segment between D18S40 and D18S66. A recently isolated gene from this region, NPC1, is mutated in the majority of patients with Niemann-Pick type C disease. We have identified a point mutation within this gene (G3097-->T; Gly992-->Trp) that shows complete linkage disequilibrium with NPD, confirming that NPD is an allelic variant of NPC1.

Linkage of Niemann-Pick disease type D to the same region of human chromosome 18 as Niemann-Pick disease type C.

Niemann-Pick type II disease is a severe disorder characterized by accumulation of tissue cholesterol and sphingomyelin and by progressive degeneration of the nervous system. This disease has two clinically similar subtypes, type C (NPC) and type D (NPD). NPC is clinically variable and has been identified in many ethnic groups. NPD, on the other hand, has been reported only in descendants of an Acadian couple who lived in Nova Scotia in the early 18th century and has a more homogeneous expression resembling that of less severely affected NPC patients. Despite biochemical differences, it has not been established whether NPC and NPD are allelic variants of the same disease. We report here that NPD is tightly linked (recombination fraction .00; maximum LOD score 4.50) to a microsatellite marker, D18S480, from the centromeric region of chromosome 18q. Carstea et al. have reported that the NPC gene maps to this same site; therefore we suggest that NPC and NPD likely result from mutations in the same gene.

New stimulation ligand of the adenovirus 2 protease.

The catalytic activity of the adenovirus cysteine peptidase is increased by a specific 11-amino-acid peptide adduct (GVQSLKRRRCF, referred to as pVIc). To identify additional peptides which might bind and alter the activity of the protease, a cysteine-constrained random peptide phage library was screened. Of 29 different phages which were isolated, 7 contained the consensus sequence VEGGS. Despite a superficial similarity to the substrate cleavage site of the protease, the peptide was not digested by the enzyme. VEGGS and pVIc altered protease activity similarly without sharing sequence similarity. To similar degrees, pVIc and VEGGS (a) stimulated the activity of the recombinant protease, (b) had no effect on viral protease, (c) increased the fluorescence emission of tryptophan residues in the protease, suggesting a conformational change, and (d) inhibited wt virus infection, but rescued ts1 infection at the nonpermissive temperature. The experiments also suggest that once the protease has been stimulated by one peptide, the other peptide has no further activity on the recombinant adenovirus cysteine protease, suggesting that the two peptides bring about the same change on the protease via different binding sites.