Biomedical subjects
Publications and source records attributed to M L Martin.
Colloidal gold was complexed with monoclonal IgG to the inner capsid of human rotavirus. The complex was then used as an immunoelectron microscopic marker to identify the location of the group-specific antigen of rotavirus.
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The inner capsid layer of human rotavirus was found to preferentially break up into large ring-like morphological units. The outer capsid was found to be composed of capsomeres covered by a thin protein or glycoprotein covering. These capsomeres appeared to be broad headed and short stemmed, similar to the type of pin used to mark locations on a map (pushpin).
Enteric virus-specific IgA and IgG present in paired human sera and colostrums were measured by the enzyme-linked immunosorbent assay (ELISA). Virus-specific IgA was present in all colostrums, but virus-specific IgG could not be detected. The reverse was true when sera were assayed. Most of these colostrums also neutralized either polio virus or reovirus, as did IgA, which was separated from a pool of colostrums by exclusion chromatography. No correlation could be made between levels of neutralizing and ELISA antibody titers in colostrums.
In the spring of 1964, 3,439 cases of acute gastroenteritis were reported from Truk District, an island group in the mid-Pacific. The causative agent was not identified in laboratory studies performed in that year. Retrospective serologic studies 15 years later with the complement fixation test and the enzyme-linked immunosorbent assay provided serologic evidence that this outbreak was caused by the human rotavirus that was first isolated in 1973.
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The hemagglutination-inhibition test for detecting rotavirus antibody was evaluated by using simian rotavirus SA-11 as hemagglutinating antigen. Results show that the test is as sensitive as either complement fixation or the enzyme-linked immunosorbent assay for detecting antibody to rotavirus in human sera.
A 29 nm non-cultivable virus (NCV) was detected in faecal extracts from children hospitalized for gastroenteritis. The NCV had a density of 1.35 g/ml in glycerol-potassium tartrate density gradients and was resistant to degradation by proteolytic enzymes, non-ionic detergents and pH extremes. The surface of these virus particles had knob-like projections which appeared to have a symmetrical arrangement. When heated to 56 degrees C, the virus was completely degraded to soluble components which could not be seen by electron microscopy.
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Enzymic and biophysical studies with purified infantile gastroenteritis virus (IGV) nucleic acid indicated that the virion contained a double-stranded RNA genome of approx. 14 x 10(6) daltons which could be separated by gel electrophoresis into eight bands of RNA which were comprised of 15 RNA species. Two major virus proteins, VP2 (mol. wt. = 135,000) and VP8 (mol. wt. = 40,000), which composed about 85% of the total virion protein, were detected in IGV particles by polyacrylamide gel electrophoresis. Eight additional minor proteins were also resolved.
The hexagonal surface structure believed to be characteristic for influenza C virus was not initially observed for a newly isolated virus of this type. After a few additional egg passages of the virus, however, the hexagonal structure could be readily seen on many virions.
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Rickettsia rickettsii was treated with ether and examined by negative-contrast electron microscopy. Group-specific complement-fixing antigen was seen to be originating from the cell wall. The antigen was composed predominately of round particles 10 to 60 nm in diameter. Intact R. rickettsii and antigen from ether-treated organisms were purified by density gradient centrifugation and analyzed by polyacrylamide gel electrophoresis. The whole rickettsial cell was composed of a minimum of 30 proteins which ranged in molecular weight from about 23,000 to 155,000. The "soluble" antigen contained nine proteins ranging in molecular weight from about 28,000 to 150,000.
Negative-contrast electron microscopy revealed that the outer layer of the envelope of rickettsiae is composed of a matrix of tetragonally arranged subunits. The layer projects approximately 7 nm from the cell wall. It is suggested that this outer layer is analogous to the structure considered capsule-like in morphology.
The complement-fixing antigens present in tissue cultures infected with varicella-zoster virus were separated into four components. There were (i) a cell-free soluble antigen, (ii) a cell-associated soluble antigen, (iii) a cell membrane-associated antigen, and (iv) a virion antigen. All four antigens were reactive with sera from patients with varicella or zoster, and about 90% of the total complement-fixing activity was found to be nonvirion associated.
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