Experimental Search for Neutron to Mirror Neutron Oscillations as an Explanation of the Neutron Lifetime Anomaly.

An unexplained >4σ discrepancy persists between "beam" and "bottle" measurements of the neutron lifetime. A new model proposed that conversions of neutrons n into mirror neutrons n^{'}, part of a dark mirror sector, can increase the apparent neutron lifetime by 1% via a small mass splitting Δm between n and n^{'} inside the 4.6 T magnetic field of the National Institute of Standards and Technology Beam Lifetime experiment. A search for neutron conversions in a 6.6 T magnetic field was performed at the Spallation Neutron Source which excludes this explanation for the neutron lifetime discrepancy.

A concept of a broadband inverted geometry spectrometer for the Second Target Station at the Spallation Neutron Source.

BWAVES is an acronym for Broadband Wide-Angle VElocity Selector spectrometer, indicating that a novel WAVES (Wide-Angle VElocity Selector) device will be used to select the velocity/wavelength of the detected neutrons after they are scattered by the sample. We describe a conceptual design of BWAVES, a time-of-flight broadband inverted-geometry neutron spectrometer for the Second Target Station at the Spallation Neutron Source operated by Oak Ridge National Laboratory. Being the first inverted geometry spectrometer where the energy of the detected neutrons can be chosen by a WAVES device mechanically, irrespective of the limitations imposed by the crystal analyzers or filters, BWAVES will feature a uniquely broad, continuous dynamic range of measurable energy transfers, spanning 4.5 decades. This will enable measurements of both vibrational and relaxational excitations within the same, continuous scattering spectra. Novel approaches that are necessary for the implementation of a WAVES device at the BWAVES spectrometer will result in a spectrometer with the design and characteristics much different from those displayed by the neutron spectrometers in existence today.

Bungowannah virus--a probable new species of pestivirus--what have we found in the last 10 years?

Bungowannah virus was discovered following an outbreak of stillbirths and sudden death in young pigs. Affected animals consistently showed a myocardopathy with signs of cardiac failure. After virus isolation and PCR investigations were unsuccessful, direct fetal inoculation was undertaken. Nucleic acid purified from serum from infected fetuses was subjected to sequence-independent single-primer amplification and nucleic acid sequencing. Sequences consistent with a pestivirus were obtained. The entire genome was identified but was genetically remote from the recognized pestivirus species. This virus was not recognized by pan-pestivirus reactive monoclonal antibodies but was subsequently detected in cell cultures by immunoperoxidase staining using convalescent sow serum. Experimental infections of sows at different stages of gestation reproduced the myocarditis syndrome. Pre-weaning losses of 70 and 29% were observed following infection at days 35 and 90, respectively. Piglets infected at day 35 were shown to be persistently infected, while chronic infections were observed after fetal infection at day 55. Chronically infected piglets showed growth retardation and were viremic for up to 7 months. Myocarditis was associated with infection in late gestation (day 90). Non-pregnant sheep and cattle have been experimentally infected but with no evidence of disease. Infection of pregnant cattle in early gestation resulted in both maternal and fetal infection, but all infected fetuses mounted an antibody response to the virus. Analysis of the nucleic acid sequence confirmed that Bungowannah has a number of changes not observed in other pestiviruses. Genes encoding some of the structural proteins remain fully functional when inserted into a bovine viral diarrhea virus (BVDV) backbone. Cell culture-based studies have shown that Bungowannah virus will grow in cells extending from humans to bats as well as farm animals.

Genetic and antigenic characterization of Bungowannah virus, a novel pestivirus.

Bungowannah virus, a possible new species within the genus Pestivirus, has been associated with a disease syndrome in pigs characterized by myocarditis with a high incidence of stillbirths. The current analysis of the whole-genome and antigenic properties of this virus confirms its unique identity, and further suggests that this virus is both genetically and antigenically remote from previously recognized pestiviruses. There was no evidence of reactivity with monoclonal antibodies (mAbs) that are generally considered to be pan-reactive with other viruses in the genus, and there was little cross reactivity with polyclonal sera. Subsequently, a set of novel mAbs has been generated which allow detection of Bungowannah virus. The combined data provide convincing evidence that Bungowannah virus is a member of the genus Pestivirus and should be officially recognized as a novel virus species.

Identification of a novel virus in pigs--Bungowannah virus: a possible new species of pestivirus.

In 2003 an outbreak of sudden deaths occurred in 3-4-week-old piglets on a farm in New South Wales, Australia. There was a marked increase in the birth of stillborn foetuses. Pathological changes consisted of a multifocal non-suppurative myocarditis. A viral infection was suspected but a wide range of known agents were excluded. A modified sequence independent single primer amplification (SISPA) method was used to identify a novel virus associated with this outbreak. Conserved 5'UTR motifs, the presence of a putative N(pro) coding region and limited antigenic cross-reactivity with other members of the Pestivirus genus, support the placement of this virus in the Pestivirus genus. Phylogenetic analysis of the 5'UTR, N(pro) and E2 coding regions showed this virus to be the most divergent pestivirus identified to date.

A single amino acid is critical for the expression of B-cell epitopes on the helicase domain of the pestivirus NS3 protein.

Truncated NS3 proteins, expressed by recombinant baculoviruses, were used to investigate the location of conserved B-cell epitopes on this non-structural bovine viral diarrhoea virus (BVDV) protein. A goat anti-pestivirus antiserum, and a panel of anti-NS3 monoclonal antibodies, including the BVDV-1 specific antibody P1D8, were used to verify the presence or absence of the epitopes. Interestingly, the monoclonal antibodies reacted only with the truncated protein encompassing the helicase domain of NS3. Expression of the B-cell epitopes was dependent on, but not within, a 57 amino acid sequence at the carboxy-terminal end of this protein, supporting observations that these conserved epitopes are conformational in nature. A comparison of deduced amino acid sequences of the helicase domain from BVDV-1, BVDV-2, BDV and CSFV isolates highlighted a single amino acid that appeared to be unique to P1D8-reactive BVDV-1 isolates. Site-directed mutagenesis studies confirmed that this amino acid is critical for the expression of the BVDV-1 specific NS3 epitope recognised by the P1D8 monoclonal antibody. Surprisingly, the amino acid was also important for an epitope recognised by two group-specific monoclonal antibodies, P1H11 and P4A11. Protein modelling studies, based on the structure of the hepatitis C NS3 helicase domain, indicated that this amino acid occupies a prominent position on the surface of the protein.

Extraction and preliminary characterization of a human bronchogenic carcinoma antigen.

Saline extracts of human bronchogenic tumours, soluble in 50% saturated ammonium sulphate and also fractions from Sephadex G-200 chromatography were used to raise antisera in rabbits. After absorbing the antisera with normal tissue extracts, direct Ouchterlony tests were performed against tumour (adenocarcinomata and squamous cell carcinomata) and normal extracts. A precipitin reaction was given with all 11 tumour extracts tested at a concentration of 5 mg/ml whereas all the 9 normal lung control extracts did not react at concentrations up to 100 mg/ml. The possibility that this reaction could be related to histocompatibility differences between individuals is ruled out by the fact that in two cases tumour and normal tissue were obtained from the same patient. These studies and also precipitin-inhibition experiments have confirmed the existence of antigen associated with bronchial carcinomata and have shown that, although the antigen or a cross-reacting antigen is present in normal lung tissue, the amounts are small in comparison with the amounts extracted from tumour. Antigenic activity was contained in a single absorbance peak when fractionated by Sephadex G-200 chromatography and its elution volume indicated a molecular weight of approximately 4-0 times 10(4)D. Further purification was achieved using isotachophoresis. Preliminary characterization of the antigen has shown it to be stable at pH 4-5, resistant to heating at 50 degrees C for 30 min, to migrate on immunoelectrophoresis with a cationic mobility at PH 8-5 and to be immunologically distinct from carcinoembryonic antigen.