The statistical discriminant analysis was verified using a test set of four viruses that were deliberately excluded from the training set. The viruses whose groups were predicted using the discriminant analysis are shown in Table 2 . The first virus, feline immunodeficiency virus (FIV), uses Felis catus (domestic cat) as its primary host and CD4 as its receptor. According to the literature [22, 23] , FIV infection of humans is rare but has been reported. Our method categorized this case as nearinfection (G = 3). The second virus, classical swine fever virus, is known to be non-zoonotic and was classified as such by our method (G = 2). Thirdly, the encephalomyocarditis virus infects S. scrofa but has been known to cause sporadic infections in H. sapiens; it was classified as group 1 (G = 1) by our method. Finally, the Lass virus is known to be zoonotic and was classified as group 1 (G = 1) by our method.