Avidin-biotin enhanced reverse passive hemagglutination method for detection of HIV antigens

A new assay for HIV antigens, the avidin-biotin enhanced reverse passive hemagglutination (AB RPHA) test is described which is suitable for detection of infection in cell culture experiments. This assay is simple to perform and economical, and has sensitivity equal to or greater than that of commercial ELISA assays. The coated red cells used for this assay may be stored in the frozen or lyophilized state.     

Standardization of ELISA for detection of antibodies to orthopoxviruses

The experience with ELISA technique utilized at serological screening for orthopoxviruses in the Republic of Ivory Coast revealed factors reducing the sensitivity and the specificity of the test. It was found out that routine controls such as "positive" and "negative" sera as well as the accepted reading of the results by two-fold or higher increase of OD values as compared to the "negative" control may be not sufficient. A significantly enhanced sensitivity and specificity of reaction was achieved by simultaneous examination of each serum under study with a control antigen. Selection of optimal dilutions of each test component followed by spectrophotometric assay and calculation of results according to the given formula contributed to the same aim. As a result of these improvements the rate of antibody detection among revaccinees was enhanced from 19 to 78.8% and the titres of ELISA and virus neutralization tests correlated in 88% of cases.     

Sensitivity and specificity of the passive hemagglutination reaction applied to titration of herpes antibodies]

52 human sera were checked for herpes virus hominis type 1 antibodies by passive hemagglutination, complement fixation, neutralization tests and plaque reduction in presence of complement. A good correlation was observed among the results obtained by the passive hemagglutination test and the plaque reduction in presence of complement. The rapidity of the indirect hemagglutination test and the sensitivity of the reaction are in favour of its routine use.     

New passive hemagglutination assay kit that uses hemagglutinin-sensitized erythrocytes for detection of rubella antibodies.

A new passive hemagglutination assay for the detection of antibodies to rubella virus hemagglutinin (PHAST-Rubella) was compared with the hemagglutination inhibition (HI) test and another passive hemagglutination test that uses a soluble rubella virus antigen (SA-PHA). When the immune responses of vaccinated individuals were monitored, similar rises in antibody titer were detected by HI or PHAST-Rubella, whereas the rise in titer detected by SA-PHA was delayed. Early-phase vaccine-induced immunoglobulin M antibody analyzed by sucrose gradient fractionation was detected to the same degree by HI and PHAST-Rubella, but early-phase immunoglobulin G antibody reacted more strongly in the HI test. When acute and convalescent serum pairs from rubella-infected individuals were evaluated, a fourfold rise in titer was detected by PHAST-Rubella and HI in 15 of 15 pairs, whereas SA-PHA, which is not intended for detecting antibody titer rises in acute infections, detected a rise in titer in only 3 of 15 pairs. In studies to determine rubella immune status, testing of 1,078 premarital and random serum specimens resulted in 98.6% agreement among the three methods in identifying rubella antibody-positive and -negative individuals. For the quantitative PHAST-Rubella procedure, a coefficient of correlation of 0.93 was obtained, in comparison with HI, when a panel of 40 characterized sera were tested. These results indicate that PHAST-Rubella reagents can detect rubella antibodies as well as HI reagents and thus may be used as a fast and accurate means of determining rubella immune status and for the quantitation of rubella antibodies.     

Evaluation of a rapid passive hemagglutination assay for anti-rubella antibody: comparison to hemagglutination inhibition and a vaccine challenge study

A rapid passive hemagglutination assay (Rubaquick) was developed that detects antibody to rubella virus in serum specimens. The test result is read visually after an incubation period of 15-30 minutes. When compared with a hemagglutination inhibition assay, the Rubaquick assay results obtained from 1,470 sera were greater than 99% specific, sensitive, and accurate. Studies of 179 paired serum specimens obtained before and 27 days after rubella vaccination showed that if antibody was detectable by the Rubaquick assay in the prevaccination specimens, the vaccine induced a secondary response consisting of increasing IgG antibody reactivity in the absence of a positive IgM response. In contrast to the positive prevaccination specimens, a negative prevaccination result was associated with IgM antibody in 98 of the 133 postvaccination specimens. Seroconversion was noted in all cases in which the prevaccination specimen was negative by the Rubaquick assay.     

Development of a method for rapid detection of Ebola virus antibodies and antigen

Despite the wide spectrum of reliable methods for identifying Ebola virus, their performance requires highly-skilled personnel, specialized laboratories, complicated equipment, and much time. Therefore, there is a need for a method that allows a physician or a medical attendant to identify the causative agent in field or bedside tests without special equipment as soon as possible. The immunoassay involving nitrocellulose membrane immuno-filtration, by using a fixed antigen (antibodies) or their immunosols, is a tried-and-true method. The time of the analysis is 7-15 min.     

A passive hemagglutination test for the detection of Brucella infection

An improved method of coupling a soluble complex, ABS, isolated from B. abortus to sheep red blood cells by chromic chloride in the presence of barbital buffer resulted in a highly specific and reliable passive hemagglutination test for the diagnosis of human and animal brucellosis. No false positive results have been found so far in more than 2000 control sera from known brucellosis-free patients or animals. On the other hand, with over 1800 test sera from patients or animals with Brucella infections, there were no false negative results, in contrast with tube agglutination or complement fixation tests.     

A simple, rapid ELISA method for the detection of DNA antibodies.

Employing an enzyme-linked immunosorbent assay (ELISA) technique the serum antibodies against native (double stranded) and denatured (single stranded) deoxyribonucleic acid (DNA) have been measured in various disease groups and a group of blood donor sera. The ELISA method has been compared with a radioimmunoassay method using native (double stranded) DNA is substrate antigen and a latex-fixation technique using particles coated with soluble deoxyribonucleoprotein (SNP). It is concluded that ELISA offers an economic and reliable alternative to isotope techniques for the assessment of antibody content in systemic lupus erythematosus (SLE) and related disease states for the clinical laboratory.     

Comparison of 2 methods for determining antibodies to collagen: the ELISA test and passive hemagglutination

For the determination of antibodies against collagen in different rheumatic diseases the authors elaborated two serological techniques. It was particularly the passive haemagglutination, which proved to be little sensitive and insufficiently reproducible. Therefore, for the determination of antibodies against collagen the authors introduced the ELISA method as one of the varieties of enzyme immunoanalysis, giving more precise results. Both methods were compared and it has become apparent that the ELISA method is more reliable and more suitable for the determination of antibodies against collagen.     

Hepatitis A virus hemagglutination and a test for hemagglutination inhibition antibodies.

Like enteroviruses, hepatitis A virus (HAV) hemagglutinated various species of erythrocytes under similar conditions. HAV-specific antibodies in both acute- and convalescent-phase sera were found to inhibit hemagglutination. The HAV hemagglutination inhibition test can be used for diagnosis, epidemiological surveillance, and vaccine assessment.     

Specificity of the passive hemagglutination test for antibody to rubella virus and the passive hemagglutination response after vaccination.

Nonspecific reactions by the passive hemagglutination test for rubella viral antibody occurred with 1.5% of sera tested. Rises in passive hemagglutination titers (greater than or equal to 4X) occurred with some serum samples taken 14 days after vaccination.     

Rapid detection of human group C rotaviruses by reverse passive hemagglutination and latex agglutination tests using monoclonal antibodies.

Reverse passive hemagglutination (RPHA) tests and a latex agglutination test with monoclonal antibodies (MAbs) were developed for the rapid detection of noncultivatable human group C rotaviruses. For RPHA tests, two MAbs, MAb 5A12 recognizing the outer capsid and MAb 13A3 recognizing the inner capsid, were separately used for the coating of sheep erythrocytes (SRBCs). Forty-six fecal samples were examined to confirm the practicality of the tests. As a result, there was concordance between the RPHA test with SRBCs coated with MAb 5A12 and polyacrylamide gel electrophoresis of viral RNA (RNA-PAGE) in 44 (95.6%) of 46 samples, while the diagnoses by the RPHA test with SRBCs coated with MAb 13A3 were in complete agreement with those by RNA-PAGE. Furthermore, a latex agglutination test with MAb 13A3 was also developed, and this test was fast enough and sensitive enough to successfully detect the viruses from most fecal samples within 2 min. The present procedures would be useful for the diagnosis of human group C rotavirus infections in clinical laboratories which are not well equipped.