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Biomedical subjects

J L Melnick

Publications and source records attributed to J L Melnick.

At least 343 records · Page 19Linked to original sources
PubMed1969

Method for testing virus stocks for viral contaminants.

A practical method for testing the purity of virus stocks has been developed and applied to reference stocks of enteroviruses. The method requires the use of a reference antiserum that is substantially free from heterotypic antibody. When selected dilutions of this antiserum are reacted with high concentrations of virus, virus intentionally allowed to escape neutralization is recovered and then identified. A contaminating virus present as a minor component of the population has a far greater probability of being revealed under the conditions of this "breakthrough" test than under the commonly used virus identity tests which customarily employ approximately 100 TCD(50) of virus and, therefore, only identify the major component of the virus population. The breakthrough test described has been used for tests of 104 reference stocks of all the enteroviruses that propagate in monkey kidney cells and human amnion cells. Although all the materials had been previously tested and approved by the commonly employed virus identity test, the breakthrough test in two instances revealed contaminating heterotypic enteroviruses present at a very low titer in the stocks. Without resorting to the stringent, elaborate, and expensive tests for absolute purity, such as those that are required to assure safety of vaccines, the use of the breakthrough test described provides reasonable assurance of purity for stock viruses to be employed as diagnostic reagents or for general laboratory research purposes where a multiplicity of viral agents and antisera are required.

Culture Techniques↗
PubMed1969

Concentration of viruses from sewage and excreta on insoluble polyelectrolytes.

The concentration of viruses from sewage by adsorption on and elution from an insoluble cross-linked copolymer of maleic anhydride is described. Viruses either added to sewage or naturally contained in sewage were preferentially adsorbed to this polyelectrolyte at a pH range of 5.0 to 6.0 and were eluted at pH 8.0 to 9.0. In a 2-month survey of viruses in sewage in the spring (April to May 1968), when viruses are at low levels, efficient and economical detection of these agents was accomplished with the polyelectrolyte-concentration method. This method lends itself to the detection of viruses present in minute amounts in fecal samples, urine, sewage, and other natural waters. Large volumes of these fluids can be treated with the polymer described, and virus can be concentrated sufficiently for detection.

Adsorption↗
PubMed1969

Replication of poliovirus in phytohemagglutinin-stimulated human lymphocytes.

Poliovirus replication has been studied in human lymphocytes during the course of blastogenesis under phytohemagglutinin (PHA) stimulation. Enhancement of virus replication in PHA-stimulated leukocyte cultures was due to an increase in number of virus-producing cells. Virus yield was approximately 10 plaque-forming units (PFU) per producing cell, both in stimulated and in nonstimulated cultures. Adsorption and penetration studies showed that freshly drawn lymphocytes (unlike other leukocytes) were resistant to virus infection, but they became susceptible to the virus during PHA stimulation. Also, the eclipse of the virus after penetration was enhanced during blastogenesis of the lymphocytes. Our findings suggested that the monocytes in the leukocyte cultures were infected initially. In PHA-stimulated cultures, the virus then spread to lymphocytes which became susceptible to virus infection during blastogenesis. Polymorphonuclear cells died within 24 to 48 hr after initiation of the cultures and apparently could not support poliovirus replication.

Antibodies↗
PubMed1968

Herpes simplex virus in mice: electron microscopy of neural spread.

Herpes simplex virus rapidly infected the trigeminal nerves of mice after intranasal inoculation. Centripetal neural spread was suggested by histologic evidence of encephalitis in the area of attachment of the trigeminal nerve. Furthermore, electron microscopy revealed virus replication primarily within Schwann cells of the trigeminal nerve, and neurons of the gasserian ganglion.

Animals↗
PubMed1968

Herpesvirus type 2: association with carcinoma of the cervix.

By utilizing the kinetics of neutralization, it was found that an antibody response to type 1 (oral) and type 2 (genital) herpesvirus infection could be independently measured and correlated with type of virus isolated from the patient. The presence of antibodies to type 1 and type 2 herpesvirus was examined in patients with carcinoma of the cervix, in matched controls, random controls, and patients with other types of malignancy. Antibodies to type 2 were found with greater frequency in patients with carcinoma of the cervix (83 percent) than in the other groups tested (0 to 20 percent). The data suggest an association of genital herpesvirus and carcinoma of the cervix.

Adult↗
PubMed1968

Abnormalities of in vitro lymphocyte responses during rubella virus infections.

In vitro rubella virus infections of lymphocytes from normal adult humans impaired their responsiveness to phytohemagglutinin (PHA) stimulations; a situation which seemed analogous to the PHA unresponsiveness of peripheral lymphocytes from babies with the congenital rubella syndrome. Such in vitro viral infection of normal cells also decreased the synthesis of normal nucleic acids and structural proteins, and abrogated the enhanced DNA synthesis induced by pokeweed and specific antigen stimulations. Furthermore, it was shown that live rubella virus, but not ultraviolet-irradiated virus, was necessary for the impaired mitogenic responses of normal leukocytes. These observations are interpreted to favor the view that the virus achieves its inhibitory effect on the action of mitogens by interference either directly or indirectly at an intracellular site. Such an action could reduce the functional potential of lymphocytes and impair their effectiveness as immunologically competent cells or as effectors in immunologic reactions.

Antibody Formation↗