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Summary The Gn subcomponent of the Gn-Gc assembly that envelopes the human and animal pathogen, Rift Valley fever virus (RVFV), is a primary target of the neutralizing antibody response. To better understand the molecular basis for immune recognition, we raised a class of neutralizing monoclonal antibodies (nAbs) against RVFV Gn, which exhibited protective efficacy in a mouse infection model. Structural characterization revealed that these nAbs were directed to the membrane-distal domain of RVFV Gn and likely prevented virus entry into a host cell by blocking fusogenic rearrangements of the Gn-Gc lattice. Genome sequence analysis confirmed that this region of the RVFV Gn-Gc assembly was under selective pressure and constituted a site of vulnerability on the virion surface. These data provide a blueprint for the rational design of immunotherapeutics and vaccines capable of preventing RVFV infection and a model for understanding Ab-mediated neutralization of bunyaviruses more generally., Graphical Abstract, Highlights • The Gn glycoprotein of Rift Valley fever virus elicits potent neutralizing antibodies • Derived a class of monoclonal antibodies that protects in an animal model • A distinct region on RVFV Gn constitutes a key site of vulnerability • Antibodies are predicted to prevent exposure of viral fusion loops, Allen et al. reveal a molecular basis of antibody-mediated neutralization of Rift Valley fever virus, an important human and animal pathogen. They isolate and demonstrate the protective efficacy of a monoclonal antibody in a murine model of virus infection, providing a blueprint for rational therapeutic and vaccine design.

This group of Vermont community health nurses from different agencies collaborated to develop a competence validation framework for maternal and child health nursing in the practice areas of perinatal client teaching, breastfeeding, and prenatal, postpartum, and newborn nursing care. The framework is based on the work of Benner, using the "competent" level of nursing practice, and delineates three parameters of competence: technical skills, interpersonal skills, and critical thinking skills. Learning resource materials, including newborn and maternal assessment guidelines, were developed for each competence area. The four competence validation tools were successfully tested for validity and reliability as well as efficiency and effectiveness by nurses in all 13 home health agencies and 12 public health district offices in Vermont. This system of competence validation is now used to support a consistently high quality of care for all recipients of Vermont's Healthy Babies, Kids, and Families services, and is available for use in other care settings.

Abnormalities have previously been reported in the pectoral muscle of embryos and young chicks from a pure strain of New Hampshire Red chickens homozygous for inherited muscular dystrophy. Fine structural studies of the musculus complexus in normal and dystrophic embryos were undertaken because of a sharp decrease in hatching by the diseased birds. Ultrastructural differences found between the normal and dystrophic embryos included a leached sarcoplasm, swollen and distorted mitochondria and tubular components, a lack of polyribosomes (myosin synthesis), and the formation of pseudostraps during differentiation of the myopathic hatching muscle. These differences may curtail differentiation until a point after the critical hatching time.

The alteration in transport specificity and jejunal absorption rates of essential amino acids before and after 2 weeks of either total starvation or isocaloric protein-free dieting were determined by an in vivo perfusion technique in 7 normal and 7 obese human volunteers. In addition, the possible change in the intestinal mucosal morphology during these dietary deprivations was investigated by light and electron microscopic examination of the tissue specimens obtained by peroral jejunal biopsy in 4 subjects. Both starvation and protein depletion resulted in the reduction of amino acid absorption rates in 12 subjects (normal as well as obese). However, the specificity of preferential amino acid absorption from equimolar mixtures of all eight essential amino acids was not affected by these dietary manipulations. Moreover, there was a decrease in the absorption rates of amino acids with high (leucine) as well as low (threonine) affinity for the amino acid carrier systems. The evidence for a reduction in the capacity of intestine to transport leucine after starvation was further supported by the demonstration of a lower rise in the plasma concentrations of leucine during the perfusion studies in starved subjects. In the face of reduced amino acid absorption rate, the jejunal mucosal histology and cell organelles appeared intact.

By use of horseradish peroxidase (Sigma Type II) as a vascular tracer the competence of the bursal microvasculature was evaluated in 15-day-old chicks. Within 5 min circulation time tracer could be identified only within the vascular tree with no leakage into the perivascular or extracellular spaces. After 10 min circulation time tracer was no longer present in the bursal vessels. Since no tracer was ever identified among the parenchymal elements of the organ these data suggest that a blood-organ (blood-bursa) barrier may exist similar to that found in thymus and brain.

The mechanism of plasma membrane turnover was investigated using the duckling salt gland as a model system. Feeding fresh water to salt-stressed ducklings results in a decrease in the Na, K-ATPase in salt gland to non-stressed levels in about 7 days, as measured by ATP hydrolysis and 3H-ouabain binding. Electron micrographs reveal that this is accompanied by a decrease in plasma membrane infoldings on the basal and lateral borders of gland secretory cells. Simultaneously there is an increase in filamentous material and a rise in acid phosphatase and peptidase activities in these cells. Cytochemistry shows that the acid phosphatase activity is mostly associated with the basal or basolateral regions of secretory cells. These ovservations could indicate that the removal of plasma membrane components is accomplished by internalization and digestion within the secretory cells.