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M Margalith

Publications and source records attributed to M Margalith.

At least 37 records · Page 2Linked to original sources
PubMed1996

HBsAg confirmation: an experimental test.

BACKGROUND: The specificity of HBsAg testing is to be confirmed with antibody blocking to avoid false positive results. OBJECTIVE: To test the experimental HrAb HBsAg-blocking activity and to use this new antibody in the verification of repeatedly reactive HBsAg blood serum samples. STUDY DESIGN: HbsAg screening of three quality control panels was followed by a comparative confirmatory test with commercial HuAb and experimental HrAb. The HrAb was used in subsequent HBsAg confirmation trials. RESULTS: A good agreement in the results obtained using the two antibodies was found, independently of the type of HBsAg neutralization step performed (either preincubation or competitive inhibition). Of the 97 repeatedly reactive HBsAg blood serum samples, 79 were 'confirmed positives'. On repeated confirmations by two antibodies, 13/18 'not confirmed' converted to 'confirmed positives', while the same five samples still remained false positive. CONCLUSION: The results suggest that (1) HrAb is as good as HuAb in HBsAg confirmation and (2) HBsAg confirmatory testing is essential in the laboratory examinations of the HBsAg repeatedly reactive samples.

Journal Article↗
PubMed1996

DNA vaccines against malaria: immunogenicity and protection in a rodent model.

Since the first demonstration of the technology a few years ago, DNA vaccines have emerged as a promising method of vaccination. In a variety of experimental systems, DNA vaccines have been shown not only to induce potent immune responses, but also to offer many advantages in terms of ease of construction, testing, and production. In this article we summarize the progress achieved in development of DNA vaccines that can protect mice from infection by the rodent malaria parasite Plasmodium yoelii, describe initial studies of immunogenicity of a malaria DNA vaccine in a primate model, and outline the strategies being employed to design the next generation of malaria DNA vaccines.

Animals↗
PubMed1995

HIV-1 DNA in fibroblast cultures infected with urine from HIV-seropositive cytomegalovirus (CMV) excretors.

Interactions between HIV-1 and CMV may be important in the pathogenesis of AIDS. We have studied whether active CMV infection alters the cell tropism of HIV-1 in dually-infected individuals. Urines from HIV-seropositive individuals excreting CMV were compared to urines from CMV non-excretors. Sixty-six urines from HIV-seropositive individuals were tested. Infectious HIV-1 was not detected in any of the concentrated urines tested. The urines were filtered, concentrated, DNase-treated and cultured on HIV-1 non-permissive human forestin fibroblasts. HIV-1 DNA was detected by PCR with pol gene primers in 5 of 39 MRHF cell cultures inoculated with CMV culture positive urine (p = 0.037). HIV-1 DNA was not detected by PCR in uninfected fibroblasts, in fibroblasts inoculated with CMV uninfected urine from 27 HIV-seropositive patients or in fibroblasts cultured with 9 CMV culture positive urines from 16 HIV-seronegative renal transplant recipients. Supernatant fluid from an HIV-1 PCR-positive culture was passaged onto another fibroblast monolayer, and these cells were negative for HIV-1 DNA. Direct inoculation of fibroblasts with HIV-1 did not yield evidence of infection by PCR. CMV infection may facilitate HIV-1 DNA entry into ordinarily non-permissive cells.

Cells, Cultured↗
PubMed1995

The significance of serum IgM IgA and IgG antibodies specific for Epstein-Barr virus as determined by immunoperoxidase assay in the rapid diagnosis of infectious mononucleosis.

The feasibility of using serum IgM, IgA and IgG antibodies specific to Epstein-Barr virus (EBV) viral capsid antigen (VCA), as determined by immunoperoxidase assay (IPA), for the early diagnosis of mononucleosis was evaluated in 65 patients with infectious mononucleosis (IMN). Control groups consisted of 104 healthy students and 15 cytomegalovirus-infected patients. In the first serum sample obtained upon admission, IgM antibodies (titer > or = 64) to EBV VCA were found in 64 of the 65 IMN patients (98%), while EBV-VCA IgA antibodies (titer > or = 32) were found in 32 patients (49%). In those particular titers, no EBV-VCA IgM or IgA antibodies were found in any of the control sera. EBV-VCA-specific IgM antibodies were also not detected in any of the 15 patients with cytomegalovirus infection. In sera obtained from IMN patients within 10 days of the onset of symptoms, 18 of 19 (95%) were IgM seropositive. This study demonstrates that serum EBV-VCA IgM antibodies (titer > or = 64) as determined by IPA are highly specific (100%) and highly sensitive (98%) and can be of value for the early and rapid diagnosis of EBV-IMN infection.

Adolescent↗
PubMed1994

Characterization of humoral immunity after DNA injection.

Antibodies to the influenza virus nucleoprotein are produced after injection of a plasmid DNA expression vector containing the nucleoprotein gene. A single injection of 10 to 100 micrograms of DNA produces IgG antibodies which first appear four to six weeks post injection. Antibody titres peak at six to eight weeks and then remain stable in most animals for many months. The antibody response at early times is dose-dependent, with higher amounts of DNA producing a faster immune response as well as higher antibody titres. Titres observed many months after injection are less dependent on DNA dose.

Animals↗
PubMed1993

Interactions between HIV-1 and cytomegalovirus in human osteosarcoma cells carrying both viruses.

Cytomegalovirus (CMV) and the human immunodeficiency virus type 1 (HIV-1) may interact in the pathogenesis of AIDS. We compared CMV replication in human osteosarcoma (HOS) cells to that in HOS cells genetically engineered to contain an envelope-deficient HIV-1 proviral construct (designated HOS-HXG). Following acute CMV infection of each cell line, HOS-HXG cells contained higher numbers of intranuclear CMV nucleocapsids than did HOS cells. Infectious CMV could be persistently detected in culture supernatant fluids of the CMV-infected HOS-HXG cells, whereas CMV was lost over several weeks from HOS cells infected with CMV in parallel. HIV-1 CMV pseudotypes were not detected in supernatant fluids from CMV-infected HOS-HXG cells. On day 119 after CMV infection, these cultures were superinfected with HIV-1. These dually infected HOS-HXG cells produced infectious HIV-1 and exhibited markedly enhanced CMV replication compared to parental CMV-infected HOS-HXG cells. Two different HIV-1 tat gene function antagonists, Ro24-7429 and chemically modified antibodies to the Tat protein, did not inhibit the replication of CMV in either acute or persistent infections of HOS-HXG cells at concentrations that inhibited HIV-1 replication.

Antiviral Agents↗
PubMed1993

Gene therapy by intramuscular injection of plasmid DNA: studies on firefly luciferase gene expression in mice.

Direct injection of nonviral, covalently closed circular plasmid DNA into muscle results in expression of the DNA in myofiber cells. We have examined the expression of firefly luciferase DNA constructs injected into adult murine skeletal muscle. Considerable variation in luciferase enzyme expression was noted among constructs with different regulatory elements, among different batches of the same DNA construct, and among similar transfection experiments performed at different times. This variation was minimized by using single batches of plasmid DNA and by performing comparable sets of experiments concurrently. A quantitative experimental protocol was defined for comparing various aspects of the transfection process. We report that a luciferase construct containing the human cytomegalovirus immediate-early gene promoter plus intron A (a construct termed "p-CMVint-lux") showed the highest expression among several constructs tested. Dose-response and time course analyses of p-CMVint-lux DNA injections showed that maximal luciferase expression was achieved with 25 micrograms of DNA at 7-14 days post-injection. Selected manipulations of the transfection process were examined for their influence on luciferase expression. Variations in the rate of DNA injection, needle size, injection volume, and vehicle temperature had no significant effect on luciferase expression. The presence of endotoxin, cationic peptide, muscle stimulants or relaxants, vasoconstrictors, metal chelators, or lysosomal lytic reagents had no significant effect on expression. However, linearization of the DNA, injection of the DNA in water rather than saline, or inclusion of a DNA intercalating agent nearly abolished luciferase expression. And finally, increasing the injection dose by giving multiple injections over a 10-day period increased expression proportionally to the number of injections.

Amino Acid Sequence↗
PubMed1993

Serum and salivary responses to oral tetravalent reassortant rotavirus vaccine in newborns.

Serum and salivary responses of 95 infants to either a standard (4 x 10(4) plaque-forming units (PFU), 47 neonates) or a high dose (4 x 10(5) PFU, 48 neonates) of tetravalent reassortant rhesus rotavirus vaccine (administered at 2 days and at 6 weeks of age) were evaluated in a double-blind clinical trial. Serum and salivary IgA antibodies to the rotavirus group A common antigen were determined by ELISA and radioimmunoassay (RIA). Serum neutralizing antibodies to rhesus rotavirus were determined by fluorescent focus reduction assay. No significant differences in responses to the high versus standard dose were noted in serum or saliva. Response was influenced by cord blood antibodies. All infants who were cord blood-negative for rhesus rotavirus neutralizing antibodies (nine who received the standard dose and 20 who received the higher dose) had serum responses, compared with 42-70% of those who were cord blood-positive. The serum response rate recorded for babies with cord blood neutralizing titres > 1000 was 44%. Infants being bottle fed had a higher serum response rate than did babies being breast fed exclusively. If serum and salivary responses were combined, the response rate reached 80% for bottle fed infants. Thus, determination of serum responses alone underestimates vaccine 'take' in infants, and more so in highly endemic areas than in areas subject only to sporadic outbreaks. However, determination of salivary responses in newborn breastfed infants may be inaccurate, due to possible persistence of antibodies derived from colostrum or breast milk.

Antibodies, Viral↗
PubMed1991

Cytomegalovirus IgG and IgA serum antibodies in a study of HIV infection and HIV related diseases in homosexual men.

The significance of serum IgG and IgA antibodies to cytomegalovirus (CMV) at various stages of human immune deficiency virus (HIV) infection was studied in 175 homosexual men. Sera were obtained from 123 HIV seropositives [41 asymptomatic, 29 with lymphadenopathy associated syndrome (LAS), 22 with AIDS related complex (ARC), and 31 AIDS patients], 17 HIV seroconverters, and 35 HIV asymptomatic seronegatives. The sera were tested blindly for CMV IgA and IgG antibodies using the immunoperoxidase assay (IPA) and CMV infected human embryo cells. Cross-sectional analysis of CMV IgG antibodies at a titer of greater than or equal to 20 showed 87% and 100% prevalence in the HIV seronegative groups and in the HIV seropositive groups, respectively (P less than 0.05). CMV IgG antibodies at a titer of greater than or equal to 80 were present in significantly higher proportions among the HIV seropositive subjects of the various groups as compared with the HIV seronegative homosexual men. However, in the HIV seronegatives who later seroconverted to HIV, a significantly higher prevalence of CMV antibodies (35%) was detected before HIV seroconversion, as compared with the persistently HIV seronegative subjects (14.3%) (P less than 0.05). The HIV seronegatives pre-HIV seroconversion also exhibited a significantly higher geometric mean titer (GMT) of CMV IgG antibodies (62.17 +/- 0.64) as compared with the persistently HIV seronegatives (34.0 +/- 0.6) (P = 0.03). Significantly higher GMTs of CMV IgG antibodies were detected in all the HIV seropositive groups as compared with the persistently HIV seronegative group. CMV IgG antibodies were not detected in the HIV seronegative subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Antibodies to polioviruses in an Israeli population and overseas volunteers.

A seroepidemiological survey of prevalence of antibodies to poliovirus types 1-3 was carried out in 1,800 residents of 30 agricultural settlements (kibbutzim) in Israel during 1980 and 1981. The survey showed that in 1980 84%, 90%, and 79% of the kibbutz residents exhibited antibodies to poliovirus types 1-3, respectively. In 1981 the figures were 81%, 91%, and 73%. Significantly lower levels of antibodies for poliovirus type 3 in 1980/1981, and for poliovirus type 1 in 1981, were noticed in the age group 6-17 years compared with the age group of greater than 18 years. Infants and young children of the kibbutzim received the Salk polio vaccine during 1957-1961 and the Sabin oral polio vaccine since 1961. Among overseas volunteers from Western countries who came during 1980 and 1981 to work in the kibbutzim for a limited period of time, 88% exhibited antibodies to poliovirus type 1, 94% to poliovirus type 2, and 75% to poliovirus type 3. No significant differences in the level of antibodies were detected between males and females or between residents in those kibbutzim using or not using wastewater for irrigation.

Adolescent↗
PubMed1990

Serum IgG and IgA antibodies specific to Epstein-Barr virus capsid antigen in a longitudinal study of human immunodeficiency virus infection and disease progression in homosexual men.

A longitudinal study of serum IgG and IgA antibody titers to Epstein-Barr virus (EBV) viral capsid antigen (VCA) was carried out in 218 homosexual men at various stages of human immunodeficiency virus (HIV) infection. The serum samples tested were obtained from the following groups: 24 HIV seroconverters, 41 persistently HIV-seropositive asymptomatic individuals, 22 seropositives who developed AIDS-related complex (ARC), 29 HIV seropositives who developed lymphadenopathy syndrome (LAS), 35 HIV seronegatives with LAS, 36 asymptomatic HIV seronegatives, and 31 AIDS patients. Blind-tested samples were titrated for IgG and IgA EBV-VCA antibodies by immunoperoxidase assay (IPA). Cross-sectional analysis indicated that all HIV-seropositive subjects exhibited significantly elevated EBV IgG and IgA antibody titers compared with HIV-seronegative subjects. The proportions with EBV-VCA IgA antibodies at a titer of greater than or equal to 128 rose during the course of HIV infection and progression of the disease: 8% in HIV seronegatives, 11% in HIV seronegatives with LAS, 25% in HIV seronegatives prior to HIV seroconversion, 44% in asymptomatic HIV seropositives, 34% in LAS, 50% in ARC, and 58% in AIDS patients. An increase in EBV-VCA IgG and IgA titers was detected following HIV seroconversion and in samples obtained 6 months before disease progression to LAS. These data suggest the possible involvement of EBV in the natural history of HIV infection and disease progression. The possibility that EBV-VCA IgA antibody levels would be of value in prediction of progression of HIV-related illness is discussed.

AIDS-Related Complex↗
PubMed1988

Two sequential outbreaks of rotavirus gastroenteritis: evidence for symptomatic and asymptomatic reinfections.

In two sequential outbreaks of rotavirus gastroenteritis that occurred in a kibbutz in southern Israel (the Negev), 32 persons (9% of the population) were ill in the first and 45 (13% of the population) in the second. Excretion of virus, changes in titers of rotavirus-specific serum IgG, or both implicated rotavirus in 72% of the illnesses in outbreak 1 and in 56% of the illnesses in outbreak 2. In both outbreaks the age-specific morbidity rate decreased with increasing age. Half (six of 12) of the children six to 27 months of age who were ill with rotavirus in outbreak 1 were ill with rotavirus again in outbreak 2, whereas two were asymptomatically infected; older children who were ill in outbreak 1 were not ill in outbreak 2. Serotype determination by enzyme-linked immunosorbent assay using monoclonal antibodies to VP7 implicated a serotype 3 virus in outbreak 1 and a serotype 1 virus in outbreak 2.

Adolescent↗
PubMed1987

Viral antibodies in agricultural populations exposed to aerosols from wastewater irrigation during a viral disease outbreak.

The presence of antibodies to eight enteroviruses (echovirus types 4, 7, and 9, coxsackievirus types A9, B1, B3, and B4, and hepatitis A virus) and varicella-zoster virus was determined during a two-year period, 1980-1981, in paired blood samples of 777 persons in selected agricultural communities (kibbutzim) in Israel. These communities were divided into several categories on the basis of wastewater utilization for sprinkler irrigation and/or fish ponds. Among the nine viral antibodies studied, there was a consistent and significant excess of antibodies to echovirus type 4 only, particularly in the age group 0-5 years, in kibbutzim that had been exposed to aerosols from sprinkler irrigation with partially treated wastewater from nearby towns. This finding may be attributed to a major national echovirus type 4 epidemic, which had peaked shortly before the collection of the blood samples. The fact that no similar excess of the other viral antibodies studied was found in any of the kibbutz categories suggests that, under nonepidemic conditions, exposure to wastewater aerosols usually does not lead to an excess in enteroviral infection. No excess of clinical cases of echovirus type 4-associated disease (meningitis or encephalitis) was detected in the communities exposed to wastewater aerosol.

Adolescent↗
PubMed1986

Changes in theophylline metabolism during postnatal development in rat liver slices.

The metabolism of theophylline was studied in liver slices of young and adult rats. Theophylline and six metabolite fractions were recognized in adult liver by thin-layer radiochromatography and high performance liquid chromatography: 1-methyluric acid; 1-methylxanthine; 1,3-dimethyluric acid and/or 3-methylxanthine; caffeine; a uracil derivative and two unknown polar compounds. Preincubation with caffeine or theobromine inhibited theophylline metabolism. Allopurinol decreased the formation of three metabolite fractions but markedly increased the production of 1-methylxanthine. SKF 525-A inhibited the overall metabolism of theophylline. The specific activity of the enzyme system was 3.2 +/- 0.4 nmoles X (g liver)-1 X hr-1 in the 4- to 5-day-old rat and increased to a peak of 25.7 +/- 1.7 in the 28-day-old; values for Km and Vmax in the 7- and 28-day-olds were 132.1 and 67.5 microM, and 23.9 and 52.1 nmoles X (g liver)-1 X hr-1 respectively. Theophylline and the same six metabolites were identified in young and adult rats, but the development pattern was not uniform. Peak age-related activity and involvement of mixed-function oxidase system are features which are common to theophylline and caffeine metabolism. Xanthine oxidase played a role in theophylline metabolism. Formation of caffeine from theophylline was not dependent on a lack of activity of other pathways.

Allopurinol↗
PubMed1986

Involvement of infants, children, and adults in a rotavirus gastroenteritis outbreak in a kibbutz in southern Israel.

An outbreak of acute gastroenteritis in a kibbutz in southern Israel, characterized by diarrhea, fever, vomiting, and abdominal pain, involved 32 kibbutz members of all ages. Nineteen percent of the children and 3.5% of the adults were ill. Transmission of the illness occurred in direct proportion to the degree of close contact, involving first infants, then mothers and nursery staff, and only later youngsters, adolescents, and fathers. Stool samples obtained from 32 kibbutz members with clinical illness and from 44 asymptomatic close contacts were examined for the presence of rotavirus antigen. Fifty-six percent of symptomatic members were positive for rotavirus antigen as compared with 4.5% of asymptomatic close contacts. Positivity of stool samples correlated inversely with the number of days elapsed after onset of illness until the sample was obtained. Serologic studies carried out on acute and convalescent sera of symptomatic and asymptomatic subjects further supported a rotavirus etiology for the outbreak. RNA profiles of stool sample extracts obtained by polyacrylamide gel electrophoresis and silver staining indicate that one electropherotype may have been responsible for the outbreak.

Adolescent↗
PubMed1986

Prevalence of antibodies to enteroviruses and varicella-zoster virus among residents and overseas volunteers at agricultural settlements in Israel.

Within the framework of a comprehensive study of the correlation between enteric diseases and wastewater utilization in agricultural settlements (kibbutzim) the prevalence of several viral antibodies was examined among kibbutz residents and overseas volunteers. The latter were assumed to be a group highly susceptible to local pathogens. For the purpose of this study the presence of antibodies against eight enteroviruses [Coxsackieviruses (COX) types A9, B1, B3, and B4, echoviruses (ECHO) types 4, 7, and 9, and hepatitis A virus (HAV)] and a nonenterovirus, varicella-zoster virus (VZV), was tested in their sera. The prevalence of these viral antibodies among 342 volunteers (aged 18 to 34 years) upon their arrival at the kibbutzim was compared with that of 176 kibbutz residents of the same age. Seroconversion (ie, acquisition of viral antibodies) was tested in 115 of the volunteers two months after their arrival at the kibbutz. The prevalence of antibodies against each of the eight enteroviruses studied was found to be significantly higher among the kibbutz residents, but the prevalence of antibodies to VZV was similarly high in both groups (52% for volunteers and 59% for kibbutz residents). The mean antibody prevalence for the seven COX and ECHO viruses was 2.1 antibodies/person in the volunteer group v 4.7 antibodies/person among the kibbutz residents. Fifty-eight percent (58%) of the residents had antibodies to HAV as compared with 14% of the volunteers. No correlation was found between seropositivity (ie, previous exposure) to various enteroviruses and the immune status to HAV or VZV in both kibbutz residents and volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗