An evaluation of two commercially available ELISAs and one in-house reference laboratory ELISA for the determination of human anti-rabies virus antibodies

Abstract

The envelope glycoprotein G of rabies virus in vaccines induces the production of neutralizing antibodies important in the protection against the disease. The measurement of anti-envelope glycoprotein antibodies is a good predictor of the degree of humoral immunity in people during anti-rabies treatment or after vaccination. Several assays exist for the serological determination of antibody protection against rabies virus infection. Antibody neutralization by the rapid fluorescent focus inhibition test (RFFIT) or the fluorescent antibody virus neutralization (FAVN) test is currently the gold standard. Performance of the highly complex RFFIT and FAVN tests, however, requires specialized reference laboratories with expertise with this assay. Although not widely used, ELISA test kits are available and may be an additional option for testing that is more accessible. The aim of the present study was to evaluate available ELISA assays for the determination of anti-rabies antibodies. We compared the Bio-Rad Platelia Rabies II ELISA, DRG Rabies Virus IgG Ab ELISA and Focus Diagnostics Rabies Antibody Detection by ELISA to RFFIT. Bland-Altman plots comparing the Bio-Rad Platelia assay and the Focus Diagnostics assay to RFFIT showed a low degree of variability between the ELISA assays and RFFIT results except in samples with high RFFIT values. The agreement, sensitivity and specificity of Bio-Rad Platelia Rabies II ELISA when compared to RFFIT were 95.1 %, 94.1 % and 95.8 %, respectively. The DRG Rabies assay compared to RFFIT had an agreement of 77.7 %, a sensitivity of 86.7 % and a specificity of 69.4 %. The agreement, sensitivity and specificity of Focus Diagnostics Rabies Detection by ELISA when compared to RFFIT were 82.2 %, 91.7 % and 73.0 %, respectively. Overall, the BioRad Platelia assay showed higher accuracy and specificity than either the DRG or Focus assays. All of these ELISAs, however, measure all antibody types and do not discriminate the neutralizing antibodies as measured by functional assays (RFFIT and FAVN) and cannot be relied upon to predict the neutralizing activity of the sera. The results of this study offer insight into the availability of alternative, less-complex methods to monitor rabies antibody titres in at-risk individuals following vaccination.

Prevalence of rabies antibodies in street and household dogs in Chandigarh, India

“…Recently, enzyme-linked immunosorbant assay (ELISA) test kits have become available which detect the level of anti-nucleoprotein antibodies which are a good predictor of degree of humoral immunity after vaccination. These kits have been evaluated and have been found to have good sensitivity and specificity (Servat et al 2007;Welch et al 2009). Also, the test can be performed within a single day without the need of a sophisticated laboratory set up.…”

Self-Amplifying mRNA Vaccines

“…In mice, neutralization titers ranging from 1:5 to 1:40 are considered to be predictive of protection in the challenge model. Therefore, the titers and kinetics measured after the second vaccination are well above this protective threshold (Welch, Anderson, & Litwin, 2009). Further research will be required to evaluate this vaccine, particularly in larger animals with a pathogenic challenge.…”

IMT504: A New and Potent Adjuvant for Rabies Vaccines Permitting Significant Dose Sparing

“…In fact, IMT504 has been demonstrated to be immunostimulatory only in rats, monkeys and humans, with IMT504 being most active in humans [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Therefore, we decided to perform a pilot study of rabies vaccination in human volunteers.…”

“…However, vaccination costs against rabies virus can be highly prohibitive and severely limit the usage of this life-saving vaccine. Intradermal regimes of vaccinations have been developed and used in tropical countries in an effort to reduce vaccination costs [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Even though this new vaccination mode may reduce costs, it requires multiple visits to vaccination facilities and skilled practitioners in order to administer the vaccine.…”

“…Titers of anti-rabies glycoprotein antibodies have been reported to have a reasonable correlation with the titers of serum neutralizing antibodies measured by the rapid fluorescent focus inhibition test (RFFIT), which is currently accepted as the gold standard technique [13][14][15]. Table 1 shows that after the second injection, all of the individuals in the IMT504 group reached protective levels (>0.5 IU/ml) as defined by the WHO [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Notably, four out of five reached levels 60 -90 times higher than the required protective level after the third dose.…”