Immunoperoxidase reaction in diagnosis of rabies

The results obtained by staining impression smears prepared from rabies positive brains revealed that with Seller's stain, Negribodies were detected in 76.28% specimens, whereas direct fluorescent antibody technique (FAT) and direct immunoperoxidase (IP) technique detected rabies antigen in 92.50% and 91.36% of brains respectively. This indicates that for giving rapid diagnosis Seller's stain may be of value but negative result does not rule out positive result. Direct FAT and direct IP were found sensitive and IP can replace FAT and is more sensitive than Sellers. Paraffin embedded sections were stained by Massignani Malferrari method, direct FAT and direct IP. All the three methods were found equally specific and sensitive. Direct FAT is only possible when fluorescent microscope is available. Its disadvantage is its impermanancy. Nonspecific reactions are also seen. These disadvantages can largely be avoided by employing direct IP since the method does not require a special kind of microscope, it can keep for a long time and it can be studied under electron microscope if desired. This test can also replace direct FAT in examining impression smears where fluorescent microscope is not available. Horseradish peroxidase from SIGMA, USA, type VI, RZ 3.0 was found most suitable.