Serum dilution neutralization test for California group virus identification and serology.
The serum dilution neutralization test was evaluated for serological diagnosis of California group arbovirus infections and identification of virus isolates. The technical advantages and the degree of subtype specificity of the serum dilution neutralization test over the hemagglutination inhibition test and the complement fixation test were demonstrated with paired specimens from human cases, single human survey sera, and sentinel rabbit sera. Twenty-one virus isolates from various geographical areas of the United States were also used to evaluate the efficacy of the serum dilution neutralization test for specific virus identification. (+info)
Removal of non-specific serum inhibitors of haemagglutination of rubella virus by treatment with dodecylamine-gel.
The suitability of using dodecylamine-gel for removing the serum non-antibody-like inhibitors of haemagglutination by rubella was studied. Compared with kaolin and MnCl2/heparin treatment this new procedure appears to have a higher specificity since it removes the non-antibody-like inhibitors from serum without affecting the immunoglobulin level significantly. The potential application of this procedure in routine serological analysis for rubella virus infection is discussed. (+info)
Staphylococcal protein A; its preparation and an application to rubella serology.
Good yields of staphylococcal protein A are obtained by growing the staphylococcus Cowan type 1 on cellophane agar. The activity of these preparations in removing immunoglobulin G (IgG) from human serum can be readily measured by the Mancini radial-diffusion technique and the correct in-use dilution determined. Treatment with protein A of sera from women with a history of rubella may help in the identification of those having specific antibody in the IgM and IgA fractions. This relatively simple procedure may have worthwhile application in the diagnosis of rubella. (+info)
Detection of antibody to avian influenza A (H5N1) virus in human serum by using a combination of serologic assays.
From May to December 1997, 18 cases of mild to severe respiratory illness caused by avian influenza A (H5N1) viruses were identified in Hong Kong. The emergence of an avian virus in the human population prompted an epidemiological investigation to determine the extent of human-to-human transmission of the virus and risk factors associated with infection. The hemagglutination inhibition (HI) assay, the standard method for serologic detection of influenza virus infection in humans, has been shown to be less sensitive for the detection of antibodies induced by avian influenza viruses. Therefore, we developed a more sensitive microneutralization assay to detect antibodies to avian influenza in humans. Direct comparison of an HI assay and the microneutralization assay demonstrated that the latter was substantially more sensitive in detecting human antibodies to H5N1 virus in infected individuals. An H5-specific indirect enzyme-linked immunosorbent assay (ELISA) was also established to test children's sera. The sensitivity and specificity of the microneutralization assay were compared with those of an H5-specific indirect ELISA. When combined with a confirmatory H5-specific Western blot test, the specificities of both assays were improved. Maximum sensitivity (80%) and specificity (96%) for the detection of anti-H5 antibody in adults aged 18 to 59 years were achieved by using the microneutralization assay combined with Western blotting. Maximum sensitivity (100%) and specificity (100%) in detecting anti-H5 antibody in sera obtained from children less than 15 years of age were achieved by using ELISA combined with Western blotting. This new test algorithm is being used for the seroepidemiologic investigations of the avian H5N1 influenza outbreak. (+info)
A modified rubella HI test using prestandardized reagents.
A modified haemagglutination inhibition test for rubella antibodies using prestandardized freeze-dried reagents was compared to a "standard" method. Tests of 707 serum samples showed that the modified test was sensitive and reliable by both macrotitration and microtitration techniques. The minor disadvantages of some reduction in antibody level when rubella sera were tested within one week of the rash and of spontaneous sheep erythrocyte agglutination in 0-7% of sera were out-weighed by the increased speed of the new test and the fact that it was carried out at room temperature. (+info)
Experimental production of respiratory tract disease in cebus monkeys after intratracheal or intranasal infection with influenza A/Victoria/3/75 or influenza A/New Jersey/76 virus.
A total of 28 cebus monkeys were inoculated intratracheally or intranasally with 10(6) 50% tissue culture infective doses of A/New Jersey/76 virus or 10(7) 50% tissue culture infective doses of A/Victoria/75 virus, and 8 additional monkeys received sterile allantoic fluid. Each of the animals became infected as evidenced by a serological response and/or shedding of the virus. Of the 10 animals inoculated intratracheally with A/Victoria/75 virus, 8 developed a systemic illness, and pulmonary infiltration was detected by X-ray in 7 of the 8. Administration of A/New Jersey/76 virus intratracheally to 10 monkeys produced a mild systemic illness in 2 animals and an upper respiratory tract illness in 6, but no illness developed in the remaining 2 monkeys; none of the animals developed X-ray evidence of lower respiratory tract disease. Intranasal administration of either virus failed to induce any illness or produced, at most, mild illness confined to the upper respiratory tract. These studies demonstrate that cebus monkeys are susceptible to respiratory tract infection with influenza A viruses and that the development of pulmonary disease is reflected in the appearance of easily recognizable radiological changes. (+info)
Influenza vaccination of human immunodeficiency virus (HIV)-infected adults: impact on plasma levels of HIV type 1 RNA and determinants of antibody response.
We assessed the effect of influenza vaccination on plasma levels of human immunodeficiency virus type 1 (HIV-1) RNA and the impact of age, plasma HIV-1 RNA level, CD4 cell count, and anti-HIV therapy on immune response. Forty-nine adults (mean age, 38.7 years; mean CD4 cell count +/- SD, 190 +/- 169/mL; mean plasma HIV-1 RNA level +/- SD, 154,616 +/- 317,192 copies/mL) were immunized. Elevations of > or = 0.48 log in plasma HIV-1 RNA levels occurred in two (4%) of 49 subjects within 4 weeks of vaccination. A fourfold or greater increase in antibody titer occurred in 13 (45%) of 29 subjects, correlating directly with CD4 cell count (P = .002) and inversely with plasma HIV-1 RNA level (P = .034). By multivariate analysis, CD4 cell count was a stronger predictor of antibody response than was plasma HIV-1 RNA level. We conclude that increases in plasma HIV-1 RNA levels following influenza vaccination are rare and transient and that antibody response is impaired with CD4 cell counts of < 100/mL and plasma HIV-1 RNA levels of > 100,000 copies/mL. Prospective trials are needed to evaluate the impact of highly active therapy on immune response after vaccination. (+info)
Further characterization of IgA in chicken serum and secretions with evidence of a possible analogue of mammalian secretory component.
Immunochemical studies of the intestinal secretory immune system of the chicken have led to further characterization of IgA in bile, intestinal contents and serum. A component was detected in late Sephadex G-200 fractions of caecal and intestinal contents which showed partial identity with bile, intestinal and a high molecular weight fraction of serum IgA. This component showed similar sedimentation characteristics to bovine serum albumin in sucrose density gradients, a fast electrophoretic mobility on polyacrylamide gel and is a possible analogue of mammalian secretory component (SC). Fractionation of serum from birds affected with infectious synovitis revealed two moleculare classes of IgA. Comparative double diffusion studies produced a reaction of complete identity between bile IgA and high molecular weight serum IgA (15S) and partial identity with low molecular weight serum IgA (7S), suggesting a lack of an SC determinant on the latter. A spur of partial identity between 15S and 7S serum IgA was also observed. Although no direct structural homology with mammalian or human IgA could be demonstrated by immunological cross-reactivity, the similarities of molecular characteristics, particularly emphasized by the presence of a secretory component, favour a functional analogy between the secretory immune system of the fowl and mammalian species. (+info)