Studies on the pathogenicity of enterovirus-like viruses in chickens.

FP3 and 612 viruses are enterovirus-like viruses. Antibody to these viruses is widespread in chicken flocks, but nothing is known about their pathogenicity. Seven experiments were carried out to investigate the tissue tropism and associated pathology of these novel fowl enterovirus-like viruses and to compare these with the effects of the previously studied enterovirus-like viruses, ELV-1 and avian nephritis (ANV). ANV is now classified as an astrovirus. Preliminary experiments were carried out with FP3 virus, 612 virus and ELV-1 to determine the distribution of viral antigen. Each preliminary experiment was followed by a larger experiment that included more birds and in which a greater range of tissues was studied. It was shown that all four viruses studied replicated in the intestine and had differing abilities to spread to other tissues. Histological changes were present in most antigen-positive tissues but they were usually relatively mild. ELV-1 was associated with the most severe intestinal lesions, followed by FP3 virus. FP3 virus produced lesions in the kidney that were marginally more severe than those caused by the G-4260 strain of ANV. FP3 virus also caused pancreatic lesions. The 612 virus was found to be only mildly pathogenic in specific pathogen free chickens.

Isolation of bovine adenovirus serotype 6 from a calf in the United Kingdom.

Two viruses, designated 99-8130(C) and 99-8130(I), were isolated in calf testis cells from the colon and ileum, respectively, of a suckled beef calf which had developed dysentery and died. Electron microscopy indicated that the mean (sd) size of the viral particles, 83 (2.5) nm, and their morphology were consistent with their being members of the family Adenoviridae. They were confirmed as adenoviruses by PCR when products of the expected size (608 bp) were amplified from both isolates by using a primer pair specific for members of the genus Atadenovirus. A comparison of the sequence of a 567 bp segment of the 99-8130(C) amplicon with that of other prototype bovine adenovirus (BAdV) strains of atadenoviruses identified the isolate as BAdV serotype 6 (BAdV-6), which had 99.3 per cent and 100 per cent identities at the nucleotide and amino acid levels, respectively, with the prototype BAdV-6 strain 671130. A virus neutralisation test was developed and indicated a high prevalence of antibody to BAdV-6 in Northern Irish cattle. There was no evidence of adenoviral inclusions in tissues from the affected calf and no antigen was detected when the tissues were stained by an immunoperoxidase technique, using a homologous antiserum raised in rabbits. The two viruses were the third reported isolation of BAdV-6, and the first from a clinically ill bovine animal.

Carbon monoxide binding by de novo heme proteins derived from designed combinatorial libraries.

Carbon monoxide binding was studied in a collection of de novo heme proteins derived from combinatorial libraries of sequences designed to fold into 4-helix bundles. The design of the de novo sequences was based on the previously reported "binary code" strategy, in which the patterning of polar and nonpolar amino acids is specified explicitly, but the exact identities of the side chains are varied extensively.(1) The combinatorial mixture of amino acids included histidine and methionine, which ligate heme iron in natural proteins. However, no attempt was made to explicitly design a heme binding site. Nonetheless, as reported previously, approximately half of the binary code proteins bind heme.(2) This collection of novel heme proteins provides a unique opportunity for an unbiased assessment of the functional potentialities of heme proteins that have not been prejudiced either by explicit design or by evolutionary selection. To assess the capabilities of the de novo heme proteins to bind diatomic ligands, we measured the affinity for CO, the kinetics of CO binding and release, and the resonance Raman spectra of the CO complexes for eight de novo heme proteins from two combinatorial libraries. The CO binding affinities for all eight proteins were similar to that of myoglobin, with dissociation constants (K(d)) in the low nanomolar range. The CO association kinetics (k(on)) revealed that the heme environment in all eight of the de novo proteins is partially buried, and the resonance Raman studies indicated that the local environment around the bound CO is devoid of hydrogen-bonding groups. Overall, the CO binding properties of the de novo heme proteins span a narrow range of values near the center of the range observed for diverse families of natural heme proteins. The measured properties of the de novo heme proteins can be considered as a "default" range for CO binding in alpha-helical proteins that have neither been designed to bind heme or CO, nor subjected to genetic selections for heme or CO binding.