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Biomedical subjects

M Brugh

Publications and source records attributed to M Brugh.

At least 19 recordsLinked to original sources
PubMed1990

Effects of chicken embryo age on time to death following infection by avian influenza viruses: implications for distinguishing highly pathogenic isolates.

When white leghorn (WL) chick embryos ranging in age from 8 to 13 days were inoculated with a variety of avian influenza virus (AIV) isolates, strain-specific differences in embryo mean death times (MDT) were observed. Non-highly pathogenic (nHP) strains killed 8 or 9 day-old embryos much more rapidly than 12 or 13 day-old embryos. Highly pathogenic (HP) strains, however, were less sensitive to embryo age resulting in similar MDTs in both older and younger embryos. These observations were consistent over a broad range of virus doses for both HP and nHP strains. When a HP derivative of H5N2 AIV was compared to its nHP parent, the derivative killed older embryos more rapidly than the parent virus, while MDTs in younger embryos were the same for both parent and derivative. The two strains further exhibited clear differences in the structure of their respective hemagglutinin, a previously described pathogenicity determinant for this virus. Thus it may be possible to readily demonstrate the HP phenotype in AIV strains based on MDT measurements in WL embryos.

Animals↗
PubMed1988

Serological monitoring of eastern wild turkeys for antibodies to Mycoplasma spp. and avian influenza viruses.

From 1981 through 1986, plasma or serum samples were obtained from 322 wild turkeys (Meleagris gallopavo) from Georgia (n = 111), Kentucky (n = 21), Louisiana (n = 22), North Carolina (n = 118), Tennessee (n = 19), Missouri (n = 24) and Iowa (n = 7). These samples were tested for antibodies to Mycoplasma gallisepticum (MG) and in most instances, M. synoviae (MS), M. meleagridis (MM), and avian influenza (AI) virus. All 322 turkeys were seronegative for MG by the rapid plate agglutination (RPA) test. All of a subsample (n = 147) also were negative (titer less than or equal to 1:40) for MG by the hemagglutination inhibition (HI) test. Five of 253 turkeys (2%) were seropositive (+4 reaction) for MS by the RPA test; however, HI tests for MS on these five turkeys were negative as were attempts to isolate MS from trachea and homogenized lung tissue. Three of 253 turkeys (1%) were seropositive (+1 to +3 reactions) for MM by the RPA test. None of 210 turkeys had antibodies to AI by the agar gel precipitation test. These data suggest that populations of native eastern wild turkeys are not important in the epizootiology of MG, MS, MM, or AI.

Animals↗
PubMed1979

Immunization of chickens and turkeys against avian influenza with monovalent and polyvalent oil emulsion vaccines.

Chickens and turkeys vaccinated with inactivated virus oil-emulsion vaccines containing different concentrations of either 1 (monovalent) or 4 (polyvalent) strains of avian influenza virus (AIV) were challenged-exposed with virulent AIV A/chicken/Scotland/59 or A/turkey/Ontario/7732/66. Four of 6 vaccines protected completely against postexposure mortality. Vaccine valency did not alter the serologic and challenge-exposure responses of chickens vaccinated with AIV A/turkey/Wisconsin/68, which was the virus component common to both monovalent and polyvalent vaccines. The magnitude of the serologic responses and protection against challenge-exposure were dependent on the concentration of virus in the vaccines. These data indicate that control of virulent AIV in chickens and turkeys by vaccination with inactivated vaccines may be feasible.

Animals↗
PubMed1978

Inactivated Newcastle disease vaccines: influence of virus concentration on the primary immune response.

Inactivated vaccines of high potency could play a valuable role in Newcastle disease control programs. We determined the influence of virus concentration and method of concentration on the immune response of chidkens to inactivated vaccines. We used the LaSota strain of virus concentrated by either ultracentrifugation of polyethylene glycole precipitation. Virus concentration has a significant effect (P less than or equal to .01) on serum antibody levels at 2, 3, 4, and 6 weeks after vaccination; but during this same period, the antibody response was not significantly influenced by method of concentration. Virus concentration increased beyond 2000 hemagglutination units did not significantly increase (P greater than or equal to .05) the magnitude of the antibody response.

Animals↗
PubMed1977

Butylated hydroxytoluene protects chickens exposed to Newcastle disease virus.

Dietary butylated hydroxytoluene, an antioxidant widely used in food and feed processing, prevents mortality of chickens exposed to virulent Newcastle disease virus and prevents the serological response of chickens exposed to avirulent Newcastle disease virus. This chemoprophylactic effect is evident when chickens are fed diets containing concentrations of butylated hydroxytoluene normally used for antioxidant purposes (100 to 200 parts per million of total diet).

Animals↗
PubMed1977

Reactivation of Newcastle Disease Virus Neutralized by Antibody.

In an effort to improve current technology for detection of Newcastle disease virus in convalescent birds, a procedure has been developed for efficient reactivation of virus that has been neutralized by antibody. The reactivation capabilities of fluorocarbon treatment, ultrasonic treatment, pH extremes, and proteolytic digestion were evaluated using the LaSota strain of virus. Reactivation was maximum after proteolytic digestion with either trypsin or papain, and reactivation effciency was up to 100%, depending on the enzyme used for digestion and the amount of antibody in the neutralization mixture. Reactivation at pH extremes was considerably less efficient than reactiviation by proteolytic digestion, and neither fluorocarbon nor ultrasonic treatments effectively recovered antibody-neutralized Newcastle disease virus.

Antibodies, Viral↗
PubMedDate not supplied

Simulation of maternal immunity by inoculation of immune yolk preparations into the yolk sac of 1-day-old chickens.

Yolk harvested from eggs laid by hens hyperimmunized with killed Newcastle disease virus (NDV) was inoculated into the yolk sac of 1-day-old specific-pathogen-free (SPF) chickens. Serum hemagglutination-inhibition antibody titers reached maximum levels 1 to 4 days after yolk inoculation and declined at a rate similar to that reported for naturally acquired maternal antibody. Expected levels of immune interference were observed when yolk-inoculated chickens were vaccinated with a conventional oil-emulsion NDV vaccine. These results show that yolk-sac inoculation with yolk antibody is a suitable approach for producing maternally immune chickens for laboratory studies.

Animals↗
PubMedDate not supplied

Re-evaluation of the pathogenicity of A/chicken/Alabama/75 (H4N8) influenza virus.

Avian influenza (AI) virus A/chicken/Alabama/7395/75 (H4N8), a putatively non-pathogenic virus associated with a self-limiting outbreak of severe disease in commercial layers, was selectively passed in chickens or in cell cultures and then in chickens to determine whether virus with increased pathogenicity would emerge. When 20 derivatives of the parental virus were each inoculated intranasally and intratracheally in leghorn hens, mortality rates ranged from zero (0/24) to 25% (6/24); mortality was 4% (1/24) for hens inoculated with the parental virus. Many virus reisolates (51/144) from hens that died exhibited high pathogenicity, killing at least six of eight intravenously inoculated 4-week-old chickens. Most derivatives examined produced plaques in trypsin-free cell cultures more efficiently than the parental virus, but the highest plaquing efficiencies observed (10%) were lower than would be expected (100%) for highly pathogenic subtype H5 or H7 AI viruses. These results confirm that the Alabama H4N8 virus can acquire increased pathogenicity upon passage in chickens and suggest that it may have acted alone in producing the severe disease observed in laying chickens in Alabama.

Animals↗
PubMedDate not supplied

Amantadine resistance among hemagglutinin subtype 5 strains of avian influenza virus.

Several avian influenza virus strains of hemagglutinin subtype 5 were assayed for sensitivity to the antiviral drug amantadine. Most strains exhibited little sensitivity to the drug as measured by plaque reduction. The A/Chicken/Scotland/59 (CS59), however, was highly sensitive, making it easily distinguishable from the other H5 strains. Drug sensitivity of the viruses was also assayed in chicken embryos. The in ovo patterns of amantadine sensitivity differed from those detected in cell culture. The CS59 isolate could not be distinguished from all the other strains on the basis of its response to amantadine in ovo. Although amantadine protected chickens inoculated with CS59 from morbidity and mortality, drug-resistant viruses were readily isolated from the infected birds. As found with other amantadine-resistant variants, the structure of the matrix gene was altered in the resistant isolates. These results demonstrate that amantadine resistance is widespread among avian influenza viruses of the H5 subtype, that drug sensitivity in cell culture does not necessarily reflect responses to amantadine in ovo and in vivo, and, as previously found, amantadine-resistant derivatives of H5 strains may be isolated from birds protected by the drug.

Amantadine↗
PubMedDate not supplied

Emergence of highly pathogenic virus during selective chicken passage of the prototype mildly pathogenic chicken/Pennsylvania/83 (H5N2) influenza virus.

The prototype mildly pathogenic A/chicken/Pennsylvania/21525/83 (H5N2) avian influenza virus, which was isolated more than 5 months before the emergence of highly pathogenic virus in the major 1983 Pennsylvania outbreak, was examined for the presence of minority subpopulations of highly pathogenic virus. Selective serial passage of the parental mildly pathogenic virus in leghorn hens did not lead to recovery of highly pathogenic virus. However, several highly pathogenic reisolates were recovered from hens inoculated with either of two mildly pathogenic virus clones selected for their ability to efficiently produce plaques in trypsin-free chicken embryo fibroblasts. Unlike the parental virus, these reisolates caused high mortality in chickens and produced postmortem lesions typical of highly pathogenic avian influenza. Electrophoretic mobilities of the hemagglutinin glycoproteins of the highly pathogenic derivatives resembled those of the prototype highly pathogenic A/chicken/Pennsylvania/1370/83 (H5N2) virus isolated in October 1983. These results suggest that unrecognized subpopulations of highly pathogenic virus may have infected Pennsylvania chickens for several months before emerging as the clinically manifest component of the virus population.

Animals↗
PubMedDate not supplied

Preparation of inactivated oil-emulsion vaccines with avian viral or Mycoplasma antigens.

The influence of the composition of water-in-oil emulsions on their physical characteristics was determined by preparing experimental emulsions with various water-to-oil ratios and various emulsifiers. Emulsions containing Tween 80 in the aqueous phase and Arlacel A or Arlacel 80 in the oil phase were lower in viscosity than emulsions containing only an oil-phase emulsifier. Viscosity decreased as the concentration of oil increased. Oil-emulsion vaccines prepared with aqueous- and oil-phase emulsifiers had low viscosity, were stable for more than 12 weeks at 37 C, and induced a marked primary antibody response in chickens.

Animals↗
PubMedDate not supplied

Characterization of infectious bronchitis virus using monoclonal antibodies.

Three monoclonal antibodies (MABs) reactive against two structural proteins--the nucleoprotein (NP) or the surface (S) protein--of avian infectious bronchitis virus (IBV) were produced and characterized. The MABs did not neutralize virus infectivity or inhibit hemagglutination. Their reactivity patterns with the homologous strain and eight heterologous strains of IBV were determined using the indirect immunoperoxidase test, the indirect immunofluorescent test, transfer-immunoblotting of separated proteins, and a dot-immunoblotting assay (DIA). Two MABs, NP- or S-protein-specific, reacted with all nine strains; one (NP-specific) reacted with only two strains. The two MABs reacting with all nine strains of IBV also detected 18 IBV field isolates of unknown serotype in the DIA. The MAB detecting only two strains did not react in the DIA. The diagnostic application of these MABs appears promising.

Animals↗
PubMedDate not supplied

In ovo competition between distinct virus populations in an avian influenza isolate.

Embryo lethality patterns induced by an avian influenza virus isolate (A/Tk/Ws/68/H5N9) suggested that it contained more than one genetic form. Two different virus populations were recovered from the isolate by plaque isolation and limit-dilution cloning and were characterized with respect to their biological and molecular properties. They were very closely related but exhibited strikingly different mean death times (MDT) in 10-day-old chick embryos. One was rapidly embryo lethal (REL), while the other was slowly embryo lethal (SEL). The REL isolate demonstrated a small but measurable mortality rate in 4-week-old chicks, as did the parental isolate. The SEL isolate, however, was nonlethal to 4-week-old chicks. The embryo MDT induced by the parental isolate revealed a biphasic death pattern reflecting expression of both REL and SEL populations. Mixing experiments, using different amounts of the two cloned populations, demonstrated that expression of their unique phenotypic property (either REL or SEL) was competitive. The number of early or late embryo deaths was directly related to the input levels of each respective virus. The only molecular difference thus far detected between the two populations is in the nonstructural (NS) gene, with the REL clone possessing a faster migrating electrophoretic form of that RNA than the SEL clone. Both forms of the NS gene were present in the original parental isolate. This study thus demonstrates the competitive coexistence of two closely related virus populations within a single natural isolate.

Animals↗
PubMedDate not supplied

Effect of dietary histamine on broiler chickens infected with avian reovirus S1133.

One-day-old broiler chickens were infected with either of two vaccine strains of avian reovirus S1133 and fed diets containing 0.2% histamine dihydrochloride for 21 or 35 days. Control groups received either or neither of these treatments. The most notable virus-histamine interaction observed was increased (P less than 0.01) early mortality of chickens infected with the more virulent (pullet) vaccine virus. Histamine in the diet did not affect seroconversion rates or the incidence of stunting in virus-infected chickens. Other evidence of virus-histamine interaction was proventricular enlargement and decreased (P less than 0.05) weight gains in chickens infected with the less virulent (chick) vaccine virus, but these signs were observed inconsistently. The possible clinical significance of these observations is discussed.

Animals↗