To further characterize the nature of proteolytic processing of the astrovirus capsid, we infected Caco-2 cells with a high multiplicity of astrovirus without trypsin in the presence of 5 to 10% fetal calf serum. These infections were characterized by pulse-chase labeling with [35 S]methionine, electron microscopy, gel electrophoresis of purified viral particles, and analysis of infectivity of such particles with and without added trypsin. Pulse-chase experiments showed that the astrovirus capsid protein was initially translated as an approximately 87-kDa protein. The 87-kDa capsid protein was rapidly converted intracellularly to a 79-kDa form which was found in smaller amounts in the cell supernatant. Purification by differential centrifugation yielded particles that appeared quite similar to trypsin-grown astrovirus particles by negatively stained electron microscopy. These particles were antigenically distinct from trypsin-treated virions as demonstrated by their various reactions with monoclonal antibodies in a solid-phase immunoassay. The purified trypsin-free particles were mainly composed of the 79-kDa capsid protein which was found to have an amino terminus at residue 71 of the entire open reading frame 2 (ORF2) product. The cleavage site was identified in a highly conserved region of the astrovirus ORF2 product. These trypsin-free particles were minimally infectious in cultured Caco-2 cells but became highly infectious (10 5 -fold increase) after trypsin but not chymotrypsin treatment. This trypsinenhanced infectivity correlated with conversion of the 79-kDa capsid protein to three smaller peptides of approximately 34, 29, and 26 kDa.Astroviruses were first identified in the stools of children with gastroenteritis and characterized by electron microscopy (EM) (18). The particles were approximately 28 nm in diameter, and some had a star-like morphology. Since the initial observation in humans, similar viruses have been identified in a variety of other mammalian species. Lee and Kurtz first demonstrated growth of the virus in tissue culture and showed that trypsin is necessary for ongoing astrovirus replication (16). The development of enzyme immunoassays (EIAs) (11,12) and reverse transcriptase PCR assays has allowed larger numbers of samples to be screened with more-sensitive tests (13,14,21). It has become apparent that astroviruses are an important cause of gastroenteritis in a variety of settings, including nosocomial infections, daycare outbreaks, and diarrhea in outpatients (5-10, 19, 20, 24, 26).The astrovirus genome consists of a single-stranded positivesense RNA of approximately 7,200 nucleotides with three open reading frames (ORFs). The first, ORF1a, encodes a serine 3C type of viral protease (27). The second, ORF1b, is separated from ORF1a by a frame shift and encodes a viral RNA polymerase (17). The third, ORF2, encodes an 87-kDa polypeptide which functions as the capsid precursor. During infection, a subgenomic RNA that encodes the capsid precursor is found in abundance in the cell cytoplas...

The integrin ␣ 4 ␤ 7 mediates lymphocyte binding to mucosal addressin cell adhesion molecule-1, and its expression defines lymphocytes capable of trafficking through the intestines and the intestinal lymphoid tissues. We examined the ability of discrete ␣ 4 ␤ 7 hi and ␣ 4 ␤ 7 Ϫ subsets of circulating memory phenotype (CD45RA Ϫ ) CD4 ϩ T cells to proliferate in response to rotavirus, a ubiquitous intestinal pathogen. ␣ 4 ␤ 7 hi memory (CD45RA Ϫ ) CD4 ϩ T cells displayed much greater reactivity to rotavirus than ␣ 4 ␤ 7 Ϫ memory or naive (CD45RA ϩ ) CD4 ϩ T cells. In contrast, ␣ 4 ␤ 7 Ϫ memory cells were the predominant population responsive to mumps antigen after intramuscular vaccination. Our results are consistent with the conclusion that natural rotavirus infection, an enteric pathogen, results in a specific circulating memory CD4 ϩ response that is largely limited to the gut-homing ␣ 4 ␤ 7 ϩ subpopulation. This phenotype is not shared with memory cells elicited by intramuscular immunization (shown here) or by skin contact allergens. The results support the hypothesis that gut trafficking memory CD4 ϩ T cells comprise cellular memory for intestinal antigens and suggest that regulated expression of ␣ 4 ␤ 7 helps target and segregate intestinal versus systemic immune response. ( J. Clin. Invest.

The United States spends more for healthcare than any other country in the world. With the rising prevalence of both Crohn's disease and ulcerative colitis, inflammatory bowel disease (IBD) represents the leading chronic gastrointestinal disease with increasing healthcare expenditures in the US. IBD costs have shifted from inpatient to outpatient care since the introduction of biologic therapies as the standard of care. Gastroenterologists need to be aware of the national cost burden of IBD and clinical practices that optimize cost-efficiency. This investigation offers a systematic review of the economics of IBD and evidence-based strategies for cost-effective management.

most likely representing RVspecific memory B cells with both gut and systemic trafficking profiles. Of note, during acute RV infection both total and RV-specific murine IgM and IgA antibody-secreting cells migrate efficiently to CCL28 (the CCR10 ligand) and to a lesser extent to CCL25 (the CCR9 ligand).Our results show that CCR10 and CCR9 can be expressed on IgM as well as IgA antibody-secreting cells in response to acute intestinal infection, likely helping target these cells to the gut. However, these intestinal infection-induced plasmablasts lack the CLA homing receptor for skin, consistent with mechanisms of differential CCR10 participation in skin T versus intestinal plasma cell homing. Interestingly, RV memory cells generally lack CCR9 and CCR10 and instead express CCR6, which may enable recruitment to diverse epithelial sites of inflammation.