Protection afforded infectious bronchitis virus-vaccinated sentinel chickens raised in a commercial environment

The protective efficacy of three infectious bronchitis virus (IBV) vaccines for sentinel chickens raised with commercial Delmarva broiler chickens was evaluated during winter 1987. Specific-pathogen-free leghorn sentinel chickens were vaccinated with Massachusetts (Mass) alone, Mass and JMK, or Mass and Arkansas (Ark) combination live vaccines, or they remained unvaccinated. Four weeks post-vaccination, sentinels were placed on broiler farms at weekly intervals for 3 weeks corresponding to weeks 4, 5, and 6 of the broiler growing cycle. Vaccine efficacy was evaluated based on IBV reisolation attempts from tracheal swabbings following a 1-week field exposure period. Sentinel chickens vaccinated with Mass and Ark combination vaccine were best protected against IBV field challenge. Only four IBV isolations were made out of a 3-week total of 36 attempts, for an 11% isolation rate. IBV vaccines containing either Mass alone or Mass and JMK offered much lower levels of protection.     

Protection of chickens from Newcastle and Marek's diseases with a recombinant herpesvirus of turkeys vaccine expressing the Newcastle disease virus fusion protein.

Recombinant strains of herpesvirus of turkeys (HVT) were constructed that contain either the fusion protein gene or the hemagglutinin-neuraminidase gene of Newcastle disease virus (NDV) inserted into a nonessential gene of HVT. Expression of the NDV antigens was regulated from a strong promoter element derived from the Rous sarcoma virus long terminal repeat. Recombinant HVT strains were stable and fully infectious in cell culture and in chickens. Chickens receiving a single intra-abdominal inoculation at 1 day of age with recombinant HVT expressing the NDV fusion protein had an immunological response and were protected (> 90%) against lethal intramuscular challenge at 28 days of age with the neurotropic velogenic NDV strain Texas GB. Recombinant HVT expressing the NDV hemagglutinin-neuraminidase provided partial protection (47%) against the same challenge. Chickens vaccinated with recombinant HVT vaccines had low levels of protection against NDV replication in the trachea when challenged ocularly. Recombinant HVT vaccines and the parent HVT strain provided similar levels of protection to chickens challenged with the very virulent RB1B strain of Marek's disease virus, indicating that insertion of foreign sequences into the HVT genome did not compromise the ability of HVT to protect against Marek's disease.     

Superradiance in a torus magnetosphere around a black hole

The coalescence of a neutron star and a black hole in a binary system is believed to form a torus around a Kerr black hole. A similarly shaped magnetosphere then results from the remnant magnetic field of the neutron star. In the strong-field case, it contains a cavity for plasma waves located between the barrier of the gravitational potential and the surrounding torus. This cavity may be unstable to superradiance of electromagnetic waves. Superradiant amplification of such waves, initially excited by turbulence in the torus, should inflate into a bubble in a time as short as approximately 0.75 (1 percent/&cjs3539;epsilon&cjs3539;2)(M/7M middle dot in circle) seconds approximately 0.15 to 1.5 seconds, assuming an efficiency &cjs3539;epsilon&cjs3539;2 = 0.5 to 5 percent and a mass M = 7M middle dot in circle. These bubbles may burst and repeat, of possible relevance to intermittency in cosmological gamma-ray bursts. The model predicts gamma-ray bursts to be anticorrelated with their gravitational wave emissions.     

Comparisons of the genomic RNA of Arkansas DPI embryonic passages 10 and 100, Australian T, and Massachusetts 41 strains of infectious bronchitis virus

The genomic ribonucleic acid (RNA) of Arkansas DPI at embryonic passages 10 and 100, Australian T, and Massachusetts 41 strains of infectious bronchitis virus (IBV) were compared using two-dimensional, 32PpCp-labeled oligonucleotide fingerprinting. The Arkansas DPI strain embryonic passage 10 was pathogenic for chickens and had one oligonucleotide not present in the attenuated passage 100. The remaining Arkansas DPI oligonucleotides had identical electrophoretic mobility. The fingerprint patterns of the Australian T, Massachusetts 41, and Arkansas DPI IBV genomes were dissimilar, thus indicating they were genetically distinct. The distinctive fingerprint patterns of these virus strains, all identified as IBV by other criteria, indicate considerable genomic variation. Fingerprinting is reliable and sensitive, and should be used in combination with other characterization methods for identifying and differentiating IBV strains.     

Viral pathogenesis of a nephrotropic infectious bronchitis virus isolated from commercial pullets.

Infectious bronchitis was diagnosed in 3-to-4-week-old pullets from an outbreak in a commercial flock in California. The disease was characterized by head swelling, watery discharge from the eyes and nostrils, and urates in kidneys. Mortality ranged from 1.8% to 12.5% per week. The isolation of a coronavirus from a suspension of pooled kidneys from clinically ill chickens at the fifth passage in 10-day-old chicken embryos, gross and histologic renal lesions, and seroconversion by enzyme-linked immunosorbent assay in inoculated birds suggested that the virus isolated was a nephrotrophic strain of infectious bronchitis virus (IBV). The virus isolate was found to be a previously unrecognized serotype, based on virus neutralization tests performed in embryonated chicken eggs. Nephropathogenicity of the IBV isolate was confirmed by inoculation of the viral isolate into specific-pathogen-free chicks and demonstration of renal lesions. The isolation of nephrotropic strains of IBV has not been reported previously from poultry in California.     

Crystal structure of bee-venom phospholipase A2 in a complex with a transition-state analogue

The 2.0 angstroms crystal structure of a complex containing bee-venom phospholipase A2 (PLA2) and a phosphonate transition-state analogue was solved by multiple isomorphous replacement. The electron-density map is sufficiently detailed to visualize the proximal sugars of the enzyme's N-linked carbohydrate and a single molecule of the transition-state analogue bound ot its active center. Although bee-venom PLA2 does not belong to the large homologous Class I/II family that encompasses most other well-studied PLA2s, there is segmental sequence similarity and conservation of many functional substructures. Comparison of the bee-venom enzyme with other phospholipase structures provides compelling evidence for a common catalytic mechanism.     

Cryopreservation of Ram Semen in Extenders Containing Soybean Lecithin as Cryoprotectant and Hyaluronic Acid as Antioxidant

A soybean lecithin‐based extender supplemented with hyaluronic acid (HA) was assayed for effectiveness to improve the quality of frozen–thawed ram semen. HA has not been tested yet in an extender containing soybean lecithin for freezing ram semen. Thus, the aim of this study was to analyse the effects of soybean lecithin at 1% or 1.5% along with HA at 0, 0.5 and 1 mg ml^‐1 in a Tris‐based extender on the motion characteristics, membrane integrity (HOST), viability, GSH peroxidase (GSH‐PX) activity, lipid peroxidation and acrosomal status after freezing–thawing. Semen was collected from four Mehraban rams during the breeding season and frozen in the six lecithin×HA extenders. The extender containing 1.5% lecithin supplemented with no HA yielded higher total motility (52.5%±1.6), viability (55.8%±1.6) and membrane integrity (44.5%±1.7), but the effects of the lecithin concentration did not reach signification. Linearity‐related parameters, ALH, BCF, lipid peroxidation, GSH‐PX activity, morphology and acrosomal status were not affected by the extender composition. In general, adding HA significantly decreased sperm velocity (1 mg ml^‐1 HA), total motility (only with 1.5% lecithin), viability (1 mg ml^‐1 HA for 1% lecithin; both concentrations for 1.5% lecithin) and membrane integrity. In conclusion, adding HA to the freezing extender supplemented with soybean lecithin failed to improve quality‐related variables in ram semen. Increasing the lecithin content could have a positive effect, but further studies are needed.     

Determination of Feeder Cell‐Based Cellular Niches Supporting the Colonization and Maintenance of Spermatogonial Stem Cells from Prepubertal Domestic Cat Testes

Recently, isolation and in vitro culture of putative spermatogonial stem cells (SSCs) in the domestic cat have been conducted. However, the cellular niche conditions that facilitate the establishment and long‐term maintenance of feline SSCs (FSSCs) have not been described. Therefore, we investigated the type of feeder cells used to stimulate colony formation and growth of FSSCs among the various factors in the FSSC niche. Spermatogonial stem cells isolated from feline testes were cultured on mitotically inactivated testicular stromal cells (TSCs) derived from cats, dogs and mice, and mouse embryonic fibroblasts (MEFs). The formation and growth of colonies derived from SSCs cultured on each type of feeder cell were identified at passage 0, and the morphology, alkaline phosphatase (AP) activity and expression of SSC‐specific genes in surviving colonies were investigated at passage 4. Among these diverse feeder cells, TSCs from cat showed the greatest colony formation, growth and maintenance of FSSCs, and SSC colonies cultured by passage 4 showed a typical dome‐shaped morphology, AP activity and expression of SSC‐specific genes (NANOG, OCT4, SOX2 and CD9). Accordingly, these results demonstrate that feline TSCs could be used as feeder cells to support the establishment and maintenance of SSCs from domestic cats.