Onchocerca volvulus heat shock protein 70 is a major immunogen in amicrofilaremic individuals from a filariasis-endemic area

Infestation with organisms causing lymphatic filariasis (i.e. Wuchereria bancrofti and Brugia malayi) results in a variety of clinical presentations. It is possible that some of the variation is due to differences in host response to parasite. To determine whether individuals who live in an endemic area but differ in their clinical manifestations respond to different filarial antigens, we screened Onchocerca volvulus expression libraries with sera from a number of individuals belonging to different clinical groups. The results of the study demonstrate that there are indeed differences in the recognition of three cloned filarial antigens and that this differential recognition is related to clinical symptomatology. The most striking finding is that an Onchocerca volvulus protein homologous to the 70 kDa Xenopus laevis heat shock protein is primarily recognized by individuals who are amicrofilaremic. Further analysis is required to determine whether these antigens play any role in the pathogenesis of filarial infection or have any potential value in protective immunity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28013/1/0000449.pd

Maintenance of the human malarial parasite, plasmodium falcipamm, in scid mice and transmission of gametocytes to mosquitoes

The study of human malaria has been hampered by the lack of small animal models for the human-infecting malarial parasites. To approach this problem, the erythrocytic stages of the human malarial parasite Plasmodiumfakiparum were adapted to in vitro growth in the presence of ascites fluid from mice homozygous for the severe-combined immunodeficiency (scid) mutation. Human red blood cells (hRBCs) infected with these adapted parasites were then injected i.p. into nonobese diabetic scid/scid (NOD/LtSz-sc/d) mice. With daily supplemental intraperitoneal boosts of uninfected hRBCs, parasites were detected in the peripheral circulation of these mice for an average of 7 d after injection. Splenectomy of NOD/LtSz-scid mice increased both the level and duration of parasitemia in the periphery, and it also promoted the circulation of mature sexual stage parasites (gametocytes). When Anopheline mosquitoes were allowed to feed on the splenectomized mice, the gametocytes were ingested by the mosquitoes and developed into oocysts in the mosquito midguts. To our knowledge, these results are the first demonstration of human malarial parasite propagation in mice and transmission of these parasites to the invertebrate vector. © 1995, Rockefeller University Press., All rights reserved

Epigenetic Alterations in RASSF1A in Human Aberrant Crypt Foci

CpG island methylation (CIM) is an epigenetic mechanism for transcriptional silencing that occurs at various stages of colon tumorigenesis. CIM has been found in serrated adenomas and hyperplastic polyps. There is also evidence for hypermethylation in aberrant crypt foci (ACF) that are found in resected colons from cancer patients. Our study addresses promoter methylation of a tumor suppressor gene, RASSF1A, within the colonic epithelium of subjects undergoing screening colonoscopies in the absence of synchronous tumors. Patients included in this study were at elevated risk for colorectal cancer (CRC) based on family history, but without a previously occurring or synchronous colon carcinoma. ACF were identified using close-focus magnifying chromendoscopy and collected by biopsy in situ. We isolated ACF and adjacent normal colonic epithelium by laser capture microdissection (LCM) and studied methylation of the RASSF1A promoter region in ACF and in adjacent normal mucosa. Expression of RASSF1A was verified using quantitative real-time polymerase chain reaction (QRT–PCR). We found that 8.6% (3 out of 35) of ACF had K-ras mutations and 24% (6 out of 25) had RASSF1A hypermethylation. Our results demonstrate that RASSF1A hypermethylation and K-ras mutations are not mutually exclusive and are present in patients at elevated risk of CRC. Importantly, CIM of RASSF1A is an early epigenetic aberration, occurring in the absence of synchronous colon tumors and is not accompanied by field effects into the surrounding epithelium

Enhanced human CD4+ T cell engraftment in beta2-microglobulin-deficient NOD-scid mice

Genetic crosses produced NOD/LtSz mice doubly homozygous for the severe combined immunodeficiency (scid) mutation and the beta2m (B2m) null allele. Both NOD/LtSz-scid/scid and NOD/LtSz-scid/scid B2m(null) mice lacked mature lymphocytes and serum Ig. However, homozygosity for the B2m(null) allele also resulted in the absence of MHC class I expression, loss of NK cell activity, accumulation of iron in the liver, and rapid clearance of human IgG1. NOD/LtSz-scid/scid B2m(null) mice supported markedly elevated levels of human T cell engraftment, compared with NOD/LtSz-scid/scid control animals, following injection with human PBMC. The increased engraftment was associated with a major increase in the number of human CD4+ T cells. Following injection with 20 million human PBMC, levels of human CD4+ T cells in the peripheral blood and spleen of NOD/ LtSz-scid/scid B2m(null) mice were 6- to 7-fold higher than those in NOD/LtSz-scid/scid mice and \u3e50-fold higher than those in C.B-17-scid/scid mice. The resulting normalization of CD4+/CD8+ ratios in NOD/LtSz-scid/scid B2m(null) mice is in sharp contrast to that observed in NOD/LtSz-scid/scid mice or in C.B-17-scid/scid mice. Circulating human IgG was cleared 6-fold more rapidly in NOD/LtSz-scid/scid B2m(null) mice than in NOD/LtSz-scid/scid mice. This rapid IgG clearance suggested a failure of the engrafted human lymphoid cells to maintain high circulating levels of human IgG. The higher levels of human CD4+ T cells and the normalization of the CD4:CD8 ratio that are observed in human PBMC-engrafted NOD/LtSz-scid/scid B2m(null) mice suggest that this system may be an excellent model for studies of HIV pathogenesis