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Biomedical subjects

M Malkinson

Publications and source records attributed to M Malkinson.

At least 55 records · Page 3Linked to original sources
PubMed1986

Detection of Marek's disease virus antigens and DNA in feathers from infected chickens.

Two novel tests, enzyme-linked immunosorbent assay (ELISA) and dot-blot hybridization, were developed to detect and quantify the antigens and DNA of Marek's disease virus (MDV) in feather tips from infected chickens. In both methods, buffered extracts of the feathers served as the same test material. The ELISA technique was compared to the conventional agar-gel precipitation (AGP) test, using the same convalescent serum from a MDV-infected bird. Of 86 feather samples tested, 34 were negative by both methods, while 6 out of 52 were ELISA positive but AGP negative. Viral antigen detection by the AGP and ELISA methods was compared with the detection of MDV DNA by the dot-blot DNA hybridization technique. At an ELISA reading (OD 405) of 0.3 and above, only 5 out of 48 DNA extracts failed to hybridize with the MDV-DNA probe. The use of the radioactively labelled MDV-DNA probe for hybridization with DNA extracts from feather tips of MDV-infected chickens was both sensitive and specific, and there was good correlation among the different tests.

Agar↗
PubMed1986

An improved ELISA method, using a streptavidin-biotin complex, for detecting Marek's disease virus antigens in feather-tips of infected chickens.

To improve sensitivity in the detection of Marek's disease virus (MDV) antigens in extracts of feather tips from infected chickens, we added a preformed streptavidin-biotin complex to the standard enzyme-linked immunosorbent assay (ELISA). Rabbit anti-chicken IgG-alkaline phosphatase that is used in the standard ELISA as the conjugate was replaced by a biotinylated rabbit anti-chicken IgG plus the streptavidin-biotin peroxidase complex (ABC) system. The ABC-ELISA system was correlated to the standard ELISA. There was increased sensitivity in the detection of MDV antigens present at low concentrations, while at the higher concentrations detection was similar to that in the standard ELISA. Both ELISA systems had the same increased sensitivity when compared with that of the agar gel precipitation (AGP) test.

Animals↗
PubMed1986

Use of lectins to detect and differentiate subtypes of Marek's disease virus and turkey herpesvirus glycoproteins in tissue culture.

Biotinylated lectins in conjunction with an avidin-biotin-peroxidase complex were used for the first time to reveal glycoproteins in chicken and duck embryo fibroblasts infected with three prototype members of the avian herpesvirus group, Marek's disease virus serotypes 1 and 2 and turkey herpesvirus. By using a panel of 10 lectins, a pattern of reactivity emerged which was both group- and type-specific. Morphological details of the lectin-stained cells include cytoplasmic granulation, capping and bleb-like protrusions of the cell membrane. Although no antibody is necessary for the reaction, this novel approach allows specific detection of the glycan moieties of viral glycoproteins as they are synthesized during infection.

Animals↗
PubMed1982

Hepatic cirrhosis suggesting aflatoxicosis in a flock of geese.

An outbreak of hepatic cirrhosis in a flock of young geese was investigated. The affected geese were cyanotic with purple beaks, shanks and footwebs. On post mortem examination severe atrophy of the liver was seen and, histologically, extensive areas of necrosis, cirrhosis and bile duct proliferation were prominent. Liver function tests and serum enzyme levels confirmed that the liver damage was extensive. The findings are compared with those found in aflatoxicosis of other avian species.

Animals↗
PubMed1980

Hen egg yolk as a source of antiviral antibodies in the enzyme-linked immunosorbent assay (ELISA): a comparison of two plant viruses.

A method of raising antibodies against plant viruses in hen egg yolk is described. Laying hens were immunized with citrus tristeza virus (CTV) or tobacco mosaic virus-avocado isolate (TMV-A). Anti-viral antibodies in the yolks of sequentially laid eggs as well as in the serum were titrated by the (heterologous) antiglobulin double antibody sandwich form of the enzyme-linked immunosorbent assay (HADAS-ELISA). Antibodies first appeared in yolk 7 days after injection and peak levels were attained on day 9-11; these levels persisted for about 6-12 days. Non-specific yolk antibodies were removed by absorption with an extract of uninfected plant tissue. Using the HADAS-ELISA technique we found that yolk titres were equal to, or higher than those in serum. The benefits of using laying hens over conventional laboratory animals as a source of antiviral antibody are discussed.

Animals↗
PubMed1980

Development of a multivalent live vaccine active against a wide range of Enterobacteriaceae.

We have constructed a deletion mutant of E. coli which lacks O-antigen - "deep rough". Living bacteria of this strain were injected repeatedly in high numbers into mice and chicks and in all cases were found to be completely harmless. In C3HeB mice, protection was obtained against a wide variety of enteric bacteria and was accompanied by an appreciable increase in titer of antibodies which cross react with LPS extracted from these bacteria. Preliminary experiments indicate that the vaccine provides protection against avian coli pathogens.

Animals↗
PubMed1978

The secretory immunological system of the fowl. VI. The effect of chemical bursectomy on immunoglobulin concentration in tears.

The effect of chemical bursectomy (3-5 mg testosterone cypionate injected at 12 days in ovo followed by 4-0 mg cyclophosphamide intraperitoneally at days 1 and 2 post-hatching) on concentration of immunoglobulins in tears and serum of chickens was investigated. Tears and serum samples were collected from bursectomized and normal control birds between days 26 and 120 post-hatching and were assayed for IgA, 7SIg and IgM concentrations using double gel-diffusion and radial immunodiffusion. No immunoglobulins other than passively acquired 7SIg were detected in the sera or tears of 23 out of 30 bursectomized birds throughout the time period. Sera were also assayed for natural agglutinins; normal birds had titres for rabbit erythrocytes which gradually increased from a mean of 1:24 at day 26 to 1:280 at day 120, while bursectomized chickens had titres of less than 1:8 throughout the experimental period. It was concluded that chemical bursectomy effectively abolished the secretory immunoglobulins normally present in tears as well as serum immunoglobulins.

Agglutinins↗
PubMed1977

Local immunity against Newcastle disease virus in the newly hatched chicken's respiratory tract.

Inoculation of 200 mean egg infectious doses (EID(50)) of lentogenic Newcastle disease virus strain B1 (NDV-B1) into the air sac of 4-day-old specific-pathogen-free chicks provided significant protection against challenge of the air sac with 100 chicken mean lethal doses (LD(50)) of velogenic NDV-H but no protection against reinfection when the challenge was by the eye. Conversely, inoculation of the eye with 200 EID(50) of NDV-B1 provided significant protection against challenge of the eye but not of the air sac with 100 chicken LD(50) of NDV-H. Birds that received both antiserum and intraocular immunization were subsequently protected against both eye and air-sac challenge. On the other hand, birds that received antiserum and air-sac immunization were protected only against air-sac challenge but not against ocular challenge. Low levels of passively administered antibody did not prevent infection of the eye or air sac but greatly reduced the mortality rate after inoculation of either the vaccine or the challenge viruses. Passively administered antibody also suppressed hemagglutination-inhibiting and virus-neutralizing antibody formation stimulated by air-sac infection but not antibody formation stimulated by ocular infection. These data are consistent with the hypothesis that local immunity is responsible for prevention of infection, since birds were immune to reinfection at one site and simultaneously susceptible at the other site of infection.

Air Sacs↗