Lillian Orciari (CDC)
Subbian Panayampalli (CDC)
Asiya Chida (CDC)
Claire Hartloge (CDC)
Jason Goldstein (CDC)
Joo Lee (CDC)
Michael Niezgoda (CDC)
Pamela Yager (CDC)
According to the World Health Organization (WHO), rabies causes greater than 59,000 deaths every year in over 150 countries as of 2017. A rapid and reliable diagnostic test for rabies is critical for prophylaxis considerations in humans bitten by animals as well as for basic surveillance and animal rabies control programs. The World Organization of Animal Health (OIE) and WHO Expert Committee on Rabies recently approved the direct rapid immunohistochemical test (DRIT) for rabies diagnostics. DRIT uses a light microscope and does not require any specialized equipment such as a freezer and incubator. There is a critical need for the reagents used for DRIT, however, as they are not currently available from any commercial source.
To meet this need, CDC researchers developed four murine anti-rabies monoclonal antibodies (mAbs), then prepared two cocktails for use in DRIT as reagents to detect rabies virus (RABV) antigen in just over 1 hour using a light microscope to read slides. The mAbs have demonstrated high sensitivity and specificity for detection of RABV and non-rabies lyssaviruses antigen. The first cocktail has the ability to detect all the RABV variants that circulate in North America, and the second cocktail of two mAbs has the ability to recognize non-rabies lyssaviruses found outside the Americas. The DRIT technique with CDC’s technology can be used for routine rabies diagnosis and enhanced rabies surveillance, particularly in conjunction with oral rabies wildlife vaccination and canine rabies elimination programs. A diagnostic DRIT kit has been designed in quantities compatible with use by low and high volume laboratories without wastage packaged in convenient 10 ml bottles capable of testing 100-200 samples. This technique offers an alternative method to direct fluorescent antibody testing (DFA) for primary diagnosis of RABV infection in infected patients or animals and adaptability for field testing. The mAbs are currently in production.
- Part of a DRIT kit for rapid detection of RABV antigen
- Alternative rabies diagnostic and confirmatory testing when the routine DFA test is unavailable
- Microscopic antigen detection test for field use if held on icepacks or where refrigeration is available
- Human or veterinary/zoonotic specimen testing
- Monitoring and public health surveillance
- Research tool
- The first cocktail of two monoclonal antibodies has the ability to detect all the rabies virus (RABV) variants that circulate in North America
- The second cocktail of two different mAbs should be able to detect non-rabies lyssaviruses found outside the Americas
- DRIT Reagent 1 has demonstrated sensitivity greater than 99% and specificity of 100% for detection of RABV antigen and non-rabies lyssaviruses antigen. DRIT Reagent 2 is still under evaluation and its sensitivity and specificity information will be updated in the future.
- Rapid test for the detection of RABV antigen in approximately 1 hour
- Alternative method for primary diagnosis of RABV in infected humans or animals
- Useful test for low-resource settings requiring only a light microscope and refrigeration for long-term storage of reagents