High-Resolution Functional Profiling of the Norovirus Genome

Human noroviruses (HuNoV) are a major cause of nonbacterial gastroenteritis worldwide, yet details of the life cycle and replication of HuNoV are relatively unknown due to the lack of an efficient cell culture system. Studies with murine norovirus (MNV), which can be propagated in permissive cells, have begun to probe different aspects of the norovirus life cycle; however, our understanding of the specific functions of the viral proteins lags far behind that of other RNA viruses. Genome-wide functional profiling by insertional mutagenesis can reveal protein domains essential for replication and can lead to generation of tagged viruses, which has not yet been achieved for noroviruses. Here, transposon-mediated insertional mutagenesis was used to create 5 libraries of mutagenized MNV infectious clones, each containing a 15-nucleotide sequence randomly inserted within a defined region of the genome. Infectious virus was recovered from each library and was subsequently passaged in cell culture to determine the effect of each insertion by insertion-specific fluorescent PCR profiling. Genome-wide profiling of over 2,000 insertions revealed essential protein domains and confirmed known functional motifs. As validation, several insertion sites were introduced into a wild-type clone, successfully allowing the recovery of infectious virus. Screening of a number of reporter proteins and epitope tags led to the generation of the first infectious epitope-tagged noroviruses carrying the FLAG epitope tag in either NS4 or VP2. Subsequent work confirmed that epitope-tagged fully infectious noroviruses may be of use in the dissection of the molecular interactions that occur within the viral replication complex.     

Differential cardiac histopathology in inbred mouse strains chronically infected with Trypanosoma cruzi.

Seven inbred mouse strains were examined for the presence of chronic Chagas' cardiomyopathy in postacute Trypanosoma cruzi infection. DBA/1, DBA/2, BALB/c, B10.T (6R), B10.Q, B10.D2, and B6 mice were infected for 100 days with the Brazil strain of T. cruzi. Standard histologic examination of cardiac tissue from these mice revealed the following relationship among the different strains based on the severity of observed inflammation (myocarditis): BALB/c, DBA/1, and DBA/2 were the most inflamed; B10.T (6R) and B10.Q were intermediate; and B6 and B10.D2 showed the least inflammation. Examination of these tissues for characteristics of myocardiopathy such as cell swelling, edema, vacuolization, necrosis, myocytolysis, connective tissue infiltration, and thinning of the right ventricular wall indicated a relative relationship among the different strains relative to the severity of cardiomyopathy as follows: BALB/c, DBA/2, and DBA/1 showed the most cardiopathy (pathopermissive); B10.T (6R) and B10.Q showed intermediate pathology; and B6 and B10.D2 showed the least involvement (pathoresistant). Anti-heart antibody present in the sera of all these mice showed specific reactivity in western blots to a 43-kDa glycoprotein from normal heart tissue. Also, anti-heart antibody enzyme-linked immunosorbent assay titers for all mouse strains were similar and showed no correlation with the severity of tissue damage. The fact that different inbred strains show various degrees of myocarditis and cardiomyopathy may be useful in the study of pathogenesis of chronic Chagas' disease. Results from this limited list of inbred strains suggest that background genes, rather than the major histocompatibility complex, play the major role in the expression of cardiac pathogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genes for serum amyloid A proteins map to Chromosome 7 in the mouse

Summary Several restriction fragment length variants have been detected among inbred strains using a mouse serum amyloid A cDNA clone. Five variants were shown to segregate as a single genetic unit and were mapped to Chromosome 7 between the glucose phosphate isomerase locus (Gpi-1) and the pink eye dilution locus (p) using recombinant inbred and congenic strains. The finding that no major MspI or BclI restriction fragments were shared between digests of DNAs from a Chromosome 7 congenic strain and its inbred partner, indicate that most, and probably all, sequences detected with the probe are clustered on Chromosome 7. Aneuploid mapping was used to show that the serum amyloid A gene complex (Saa) is proximal to the Chromosome 7 breakpoint in T(7;X)1Ct, a translocation in which the middle third of Chromosome 7 is inserted into the X-chromosome. A survey of inbred strains revealed a single common Saa haplotype and eight rare haplotypes. The complex distribution of 14 different variants suggests that recombination may have played a role in haplotype evolution.This work was supported by grants GM18684 and CA33093 from the National Institute of General Medical Sciences and the National Cancer Institute, respectively.     

7-Azaindole-3-acetic acid derivatives: Potent and selective CRTh2 receptor antagonists

High throughput screening identified a 7-azaindole-3-acetic acid scaffold as a novel CRTh2 receptor antagonist chemotype, which could be optimised to furnish a highly selective compound with good functional potency for inhibition of human eosinophil shape change in whole blood and oral bioavailability in the rat.