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J L Melnick

Publications and source records attributed to J L Melnick.

At least 19 recordsLinked to original sources
PubMed1992

Properties and classification of hepatitis A virus.

Hepatitis A virus (HAV) is a member of the picornavirus family. It was first provisionally classified as enterovirus 72, but subsequent determinations of its nucleotide and amino acid sequences showed them to be sufficiently distinct to assign the virus to a new genus. Heparna-virus (Hep-A-RNA-virus) has been suggested as the genus name. HAV shares the key properties of the picornavirus family: an icosahedral particle 28 nm in diameter with cubic symmetry, composed of 30% RNA and 70% protein. The genome is single-stranded 7.48 kb RNA, linear and positive-sense. Like other picornaviruses, HAV possesses four major polypeptides cleaved from a large precursor polyprotein. The surface proteins VP1 and VP3 are major antibody-binding sites. The internal protein VP4 is much smaller than the VP4s of other picornaviruses. As other picornaviruses, HAV has no envelope and replicates in the cytoplasm. HAV is stable to treatment with either and acid, and is much more heat-resistant than other picornaviruses. It withstands 60 degrees C for 1 h. MgCl2 stabilizes the virus to withstand temperatures up to 80 degrees C. The relative resistance of HAV to disinfection indicates a need for extra precautions in dealing with hepatitis patients and their products. Only one serotype is known. There is no antigenic cross-reactivity with other hepatitis viruses. HAV initially was identified in stool and liver preparations by employing immune electron microscopy as the detection system. Chimpanzees and marmoset monkeys are susceptible to HAV. HAV has been cultivated serially in primary explant cultures of adult marmoset livers and in cell lines of primate origin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Virus inactivation: lessons from the past.

The organizers of this meeting have assigned two tasks to me. The first is to describe the state of affairs in 1955 when several lots of Salk poliovaccine, which had been formalin-inactivated according to government regulation and had been released for use in children, were subsequently found to have retained a small amount of live virulent virus. The second task is to describe a series of experiments that we conducted 25 to 35 years ago on the influence of cations on the thermostability of viruses. Perhaps there are some lessons to be learned and some benefits for future research to be gained from this history.

Cations↗
PubMed1990

Response to trivalent oral poliovirus vaccine with and without immune serum globulin in young adults in Israel in 1988.

Fifteen cases of type 1 paralytic poliomyelitis occurred in August 1988, mainly among young adults in the Jewish population of Israel, where vaccine coverage exceeds 90%. The military forces, as a precaution against further spread of the virus, vaccinated all recruits in late September. They received oral poliovirus vaccine (OPV) simultaneously with prophylactic immune serum globulin (ISG) to protect against hepatitis A virus infection. Since it is generally not recommended to administer live vaccines simultaneously with ISG, the serologic response to OPV given at the same time as ISG was compared with the response when OPV was given alone; specimens were also available from a control group receiving ISG alone. No effect of ISG on the antibody response to OPV was found, and thus there appears to be no contraindication to giving OPV at the same time as injecting pooled ISG--particularly relevant for travelers to areas endemic for both diseases, who have to leave at short notice. Of recruits 18-19 years of age, 21% lacked antibodies to type 1 poliovirus, suggesting either a decline in antibody titers with age or a lack of vaccine potency during earlier years. After the booster, only 2% lacked type 1 antibody, and the geometric mean titer increased from 1:16 to 1:698.

Adult↗
PubMed1990

Microculture assay for isolation of human immunodeficiency virus type 1 and for titration of infected peripheral blood mononuclear cells.

To define the optimal conditions for human immunodeficiency virus (HIV) detection in microcultures, experiments were conducted with different ratios of patient and donor peripheral blood mononuclear cells (PBMCs). Donor/patient PBMC ratios ranged from 1:1 to 1:125. Optimal results were obtained when 1,500,000 donor cells were cocultured with equal or smaller quantities of patient PBMCs. Thus, virologic endpoints could be achieved by diluting patient cells. Smaller numbers of donor cells, with or without larger numbers of patients cells, resulted in lower rates of HIV isolation. Similarly, the direct stimulation of patient PBMCs with phytohemagglutinin without the addition of normal donor cells lowered the sensitivity of the assay significantly. We suggest that a microculture procedure using a fixed quantity of donor cells with different dilutions of patient cells may be useful for monitoring changing HIV levels during antiviral therapy.

Cells, Cultured↗
PubMed1990

Specific interaction of CD4-bearing liposomes with HIV-infected cells.

The CD4 molecule was reconstituted into the bilayers of large liposomes. Fluorescence microscopy and electron microscopy showed that these liposomes interact with HIV-infected H9-HT cells, delivering their contents to the cell interior. Liposomes bearing CD4 did not interact in this way with noninfected H9-HT cells nor did liposomes without CD4 interact significantly with HIV-infected cells. From electron micrographs, it appeared that HIV binds to liposomes bearing CD4; no attachment of virions to liposomes without CD4 was observed.

CD4 Antigens↗
PubMed1989

AIDS in Bulgaria.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Smoking and infectious agents and risk of in situ cervical cancer in Sydney, Australia.

In a study of 116 in situ cervical cancer patients and 193 matched community controls in Sydney, Australia, smoking was found to be a major risk factor. Current smokers had a adjusted relative risk [RR] of 4.5 compared to nonsmokers [95% confidence interval (CI) 2.2-9.1] and exsmokers a RR of 1.3 [95% CI 0.6-3.0]. There was a stepwise dose-response relationship between risk and number of cigarettes smoked (30+ cigarettes/day, RR = 5.1, 95% CI 1.5-17.3); this dose-response relationship was more marked among current smokers. Years of cigarette smoking was not consistently related to risk. Exposures to herpes simplex virus type 2 and cytomegalovirus as measured by antibody prevalence were unrelated to risk (RR = 1.1 for both measures). However, cases appeared to have more exposure than controls to herpes simplex virus type 1 (RR = 2.3, 95% CI 1.1-4.4).

Adolescent↗
PubMed1989

Viral vaccines: achievements and challenges.

In this review the present state of vaccination as a means to control viral diseases is discussed, and the needs and directions for future investigations are considered. The history of viral vaccines already in use is surveyed for guidance in what steps and background knowledge of the viral agents and the host responses to infection were necessary to their successful development. The steps requisite for demonstrating efficacy and safety of a viral vaccine also are summarized, and the features of the target populations to be protected are noted as they affect the final requirement for a successful vaccine: that it be administered in proper dosage and potency to those who need it. General remarks on the proper use of current vaccines are followed by an overview of various developments toward prospective vaccines, along with the predicted time-frames for their coming into general use. Vaccines considered include vaccines to be administered locally at the portal of entry, subunit vaccines, viruses attenuated by genetic manipulation, use of viral vectors, vaccines developed by means of recombinant DNA, synthetic peptides, and anti-idiotype vaccines, as well as new vaccines being developed by more conventional methods.

Humans↗
PubMed1989

Virus vaccines: principles and prospects.

The present status of vaccination for controlling viral diseases is reviewed, and the needs and directions for future investigations are discussed. A survey of viral vaccines now in use has shown that knowledge about the viral agents and about the hosts' responses to infection was essential for their development. The steps needed to demonstrate the efficacy and safety of a viral vaccine are summarized; the final requirement for a successful vaccine is that it be administered in proper dosage and potency to the target populations. After general remarks on the proper use of current vaccines there follows an overview of various developments in creating new vaccines, along with the predicted time-frames for their coming into general use. Topics considered include vaccines to be administered locally at the portal of entry, subunit vaccines, viruses attenuated by genetic manipulation, use of viral vectors, vaccines developed by means of recombinant DNA, synthetic peptides, and anti-idiotype vaccines, as well as new vaccines being developed by more conventional methods.

Humans↗