A Cost Effective Easy Competitive Enzyme-Linked Immunosorbent Assay Suitable for Monitoring Protective Immunity against the Rabies Virus in the Serum of Humans and Dogs

Abstract

The coverage of rabies vaccinations has been reported at 70-80% of dogs in annual reports. However, there are still outbreaks of rabies among humans and dogs in Thailand, thus indicating the necessity of ensuring seroprevalence in vaccinated dogs and efficacy of human immunization. A cost effective easy competitive enzyme-linked immunosorbent assay (CEE-cELISA) was developed here for monitoring protective immunity against the rabies virus in human and dog serum samples using monoclonal antibody clone 1-46-12, which recognizes a conformational epitope of the rabies G protein. The ELISA plate is coated with the whole viral antigen from a commercial vaccine. The serotiter measured by the CEE-cELISA and by the gold standard assay (rapid fluorescent focus inhibition test), detecting the neutralizing antibody, showed a strong correlation, with an R value of 0.958 and 0.931 in humans and dogs, respectively. These correlations were detected in the serum samples from humans and dogs at antibody concentrations up to 100 and 10 IU/ml, respectively. This CEE-cELISA could be an alternative assay for evaluating mass rabies vaccination rapidly at a low cost as well as for detecting antirabies antibodies in the serum of not only humans but also other animal species.

One-dose intradermal rabies booster enhances rabies antibody production and avidity maturation

“…This study was performed to investigate the humoral immune response following primary and booster vaccination with the rabies virus glycoprotein and rabies vaccine in high-risk village volunteers. We confirmed that the participants were primed after receiving a cost-saving rabies PrEP vaccination independent of the achievement of seroconversion (anti-rabies antibody ≥ 0.7 EU/mL) as determined using the CEE-cELISA procedures from our previous study [ 11 ]. Our other study provided evidence that CEE-cELISA is suitable for monitoring antibodies against the rabies virus in the serum of humans compared with RFFIT results and revealed a very strong correlation between CEE-cELISA and RFFIT data [ 10 ].…”

“…The anti-rabies antibody levels in the three groups, PrEP and the 1st and 2nd booster groups, on D0, D28 and D180 were detected by CEE-cELISA. The lowest concentration of an anti-rabies antibody that could be detected by the CEE-cELISA was approximately 0.7 EU/mL, which was comparable with the REFFT result at 0.5 IU/mL [ 11 ]. On D0 before immunization and D28 after immunization, the median rabies antibody level was not different among the three groups; however, on D180, the median level in PrEP (16.5 EU/mL [95% CI 7.2–24.7 EU/mL) was significantly lower than that in the 1st booster group (25.8 EU/mL [95% CI 18.9–101.2 EU/mL]) and the 2nd booster group (27.0 EU/mL [95% CI 26.0–38.2 EU/mL]) (Fig.…”

“…However, our study showed no difference in antibody levels or avidity indices between the 1st booster and 2nd booster groups. Another limitation is that the anti-rabies antibody levels measured by CEE-cELISA showed a very strong correlation with those in the RFFIT assay; however, the correlation values were detected in human sera only up to 100 EU/mL and showed no correlation with RFFIT as discussed in a previous study [ 11 ]. When the antibody concentration was greater than 100 IU/mL according to CEE-cELISA, the results could not be interpreted.…”

“…However, we observed a difference in antibody levels between the PrEP and booster groups when antibodies were detected via indirect ELISA for the rRVGP and rabies vaccine. CEE-cELISAs were developed by using the monoclonal antibody clone 1–46-12, which recognizes a conformation epitope of the rabies G protein and rabies virus vaccine as antigens for ensuring the efficacy of immunization [ 11 ], while indirect ELISA was used to detect all epitopes to rRVGP and the whole rabies virus from coatings of the rRVGP and the rabies vaccine on ELISA plates, respectively. These data indicated that at least a single ID booster dose enhanced other epitopes to rRVGP and might enhance neutralizing activity, even in low-responder participants.…”

“…Even if the WHO recommends that only those at risk whose level is below an arbitrary level should receive a booster, the gold standard detection of anti-rabies antibody, rapid fluorescent focus inhibition test (RFFIT), is difficult to access in Thailand and most Asian countries. The cost effective easy competitive ELISA (CEE-cELISA) could be an alternative assay for evaluating mass rabies vaccination rapidly at a low cost as well as for detecting anti-rabies antibodies [ 11 ].…”