Results of the cross-reactivity tests with other viruses are shown in . The test only produced positive results with the rabies virus (CVS-N2, 1088-N1, Nishigahara, ERA-C1300, and HEP-Flury). Negative results were produced with other lyssaviruses (Lagos-B19, Mokola, and Duvenhage), vesicular stomatitis virus, Oita-296/1972,19
canine adenovirus type 2, infectious canine hepatitis, canine parainfluenza virus, canine coronavirus, canine parvovirus, canine distemper virus, Japanese encephalitis virus, chikungunya virus, West Nile virus, and dengue virus type-2.
Results of cross-reactivity of rapid immunochromatographic test with different viruses*
A total of 248 samples were collected in Sri Lanka, including 115 brain samples from cats, 86 from humans, and 47 from other animals (goat, wild cat, mongoose, grey mongoose, ruddy mongoose, squirrel, rock squirrel, civet cat, rabbit, cow, buffalo, pig, goat, loris, rat, and monkey). In Bhutan, 27 brain samples were collected from cows and dogs. In Thailand, 228 brain samples were collected from dogs.
The sensitivity, specificity, PPV, NPV, accuracy, and kappa measure of agreement for the RICT when compared with the FAT are shown in .
Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and kappa measure of agreement of rapid immunochromatography test compared with fluorescent antibody test for detection of rabies virus*
The optimal temperature for the storage of the RICT was 4°C. Five FAT-positive and three FAT-negative dog brain samples produced the same results when the RICT was stored at 25°C and 37°C for 48 hours. The RICT strips stored at 37°C for 72 hours produced a positive reaction with one rabies-negative sample, i.e., 33.3% of the FAT-negative samples were positive when using the RICT in these conditions. The RICT strips stored at 40°C for 24, 48, and 72 hours produced positive reactions with two rabies-negative samples, i.e., 66.7% of the negative samples were positive when using the RICT at these conditions. All other rabies-positive samples produced a positive reaction in strips stored at different temperatures for different periods. Therefore, we do not recommend storing RICT strips at 37°C for more than 24 hours, or at 25°C for more than 72 hours.
The complete N gene was determined for five strains that produced positive results by using the FAT and RICT (strain numbers H-08-1320, H-557-10, H-951-09, H-219-08, H-1282-09). Three strains produced negative results using the FAT but positive results using the RICT (strain numbers H-457-09, H-1123-08, H-1125-08), whereas one strain (strain number H-74-10) produced a positive result with the FAT but a negative result with the RICT.
Alignment of the deduced amino acid sequence of the N genes indicated substitutions in two strains that produced positive results using the FAT and RICT. In one strain, Lys was substituted with Glu at residue 5, and in the other strain, Ala was substituted with Gly at residue 371. There were no substitutions in other three strains.