First detection of bovine noroviruses and detection of bovine coronavirus in Australian dairy cattle.

BACKGROUND AND OBJECTIVE: Noroviruses have been recognised as a significant cause of neonatal enteritis in calves in many countries, but there has been no investigation of their occurrence in Australian cattle. This study aimed to establish whether bovine noroviruses could be detected in faecal samples from Australian dairy cattle. It also sought to determine whether bovine coronaviruses, also associated with neonatal enteritis in calves, could be detected in the same faecal samples. METHODS: A selection of faecal samples that were negative for rotaviruses from dairy farms located in three geographically distinct regions of Victoria were pooled and tested by reverse transcription-PCR for the presence of noroviruses (genogroup III), neboviruses and bovine coronaviruses. RESULTS AND CONCLUSION: Genetically distinct genogroup III noroviruses were detected in two sample pools from different geographic regions and bovine coronavirus was detected in a third pool of samples. This is the first report of bovine norovirus infection in Australian cattle and suggests that future work is required to determine the significance of these agents as a cause of bovine enteric disease in Australia.

Biochemical analyses of mutations in the HSV-1 helicase-primase that alter ATP hydrolysis, DNA unwinding, and coupling between hydrolysis and unwinding.

Herpes simplex virus type 1 encodes a heterotrimeric helicase-primase composed of the products of the UL5, UL52, and UL8 genes. UL5 possesses six motifs conserved among superfamily 1 of helicase proteins. Substitutions of conserved residues in each motif abolishes DNA replication in vivo (Zhu, L., and Weller, S. K. (1992) J. Virol. 66, 469-479). Purified UL5.52 harboring a Gly to Ala change in motif V retains primase and helicase activities in vitro but exhibits a higher KM for single-stranded DNA and lower DNA-dependent ATPase activity (Graves-Woodward, K. L., and Weller, S. K. (1996) J. Biol. Chem. 272, 13629-13635). We have purified and characterized six other subcomplexes with residue changes in the UL5 helicase motifs. Each variant subcomplex displays at least wild type or greater levels of primase and DNA binding activities, but all are defective in helicase activity. Mutations in motifs I and II exhibit profound decreases in DNA-dependent ATPase activity. Mutations in motifs III-VI decrease DNA-dependent ATPase activity 3-6-fold. Since mutations in motifs III, IV, V, and VI do not eliminate ATP hydrolysis or DNA binding, we propose that they may be involved in the coupling of these two activities to the process of DNA unwinding. This analysis represents the first comprehensive structure-function analysis of the conserved motifs in helicase superfamily 1.

Replacement of gly815 in helicase motif V alters the single-stranded DNA-dependent ATPase activity of the herpes simplex virus type 1 helicase-primase.

Herpes simplex virus type 1 encodes a helicase-primase complex composed of the products of the UL5, UL52, and UL8 genes. A subcomplex consisting of the UL5 and UL52 proteins purified from insect cells also displays ATPase, helicase, and primase activities. UL5 contains six motifs conserved in superfamily I of known and/or putative helicase proteins. Consistent with the ability to hydrolyze ATP, motifs I and II resemble a nucleotide binding site. Although the role of the other four motifs is not known, single amino acid substitutions created in conserved residues in all six motifs abolish the ability of UL5 to support viral DNA replication in vivo (Zhu, L., and Weller, S. K. (1992) J. Virol. 66, 469-479). In one such mutation, a highly conserved glycine in motif V (Gly815) is replaced with an alanine. Although the UL5(G815A) protein does not support viral DNA replication in vivo, the purified UL5(G815A).52 subcomplex retains primase and helicase activities and supports strand displacement DNA synthesis on a preformed replication fork in the presence of the other HSV-1 replication proteins. The major difference between the wild-type and variant protein is that the UL5(G815A).52 subcomplex displays an increased Km for single-stranded DNA and decreased Kcat for single-stranded DNA-dependent ATPase activity. Several hypotheses for the role of motif V in the function of the UL5 helicase in HSV-1 DNA replication are considered. This is the first report of a biochemical analysis of a motif V variant in any member of helicase superfamily I.

The relationship between skin compliance, age, gender, and tactile discriminative thresholds in humans.

Earlier research has suggested that tactile sensitivity, like visual and auditory acuity, may decrease with increasing age. But are decrements in tactile sensitivity attributable to changes in the nervous system, or simply to alterations in the mechanical properties of the skin? In the present study, skin compliance and discriminative thresholds for two-point and gap stimuli were measured on the pad of the left index finger of 102 persons ranging in age from 18 to 84 years. For both types of stimuli, age was found to be a significant predictor of tactile sensitivity, even when skin compliance and gender were controlled. The relationship between increasing age and decrements in tactile discrimination is apparently not attributable to changes in the mechanical properties of the skin, but to other factors, which may include changes in the nervous system affecting the speed, quantity, or quality of information processing.

The recovery of sensory function following skin flaps in humans.

Two cross-sectional studies were made of the recovery of tactile and pain sensitivity in subjects having skin flaps in the region of the chest and neck as a result of tumor excision. In experiment 1, stimuli ranging from 2.46 to 17.10 gm of force were delivered by von Frey hairs to the flaps and comparable normal sites in 35 subjects at times ranging from 1 month to 10 years after surgery. No subjects perceived stimuli of less than 11.80 gm, thermal, or moving touch applied to flaps, whereas 21 percent perceived 11.80 gm or greater force (judged as painful applied to normal skin). The results of experiment 2 showed that these findings were not due to visual information available to subjects. Possible explanations for the fact that these results are radically different from those reported in the literature are discussed.