Relatives of rubella virus in diverse mammals

Abstract

We describe the first known relatives of rubella virus ( Matonaviridae: Rubivirus) ¹ in Africa and Europe. Ruhugu virus, the closest relative of rubella virus, was found in apparently healthy cyclops leaf-nosed bats ( Hipposideros cyclops) in Uganda. Rustrela virus, outgroup to the rubella/ruhugu clade of viruses, was found in acutely encephalitic placental and marsupial animals at a zoo in Germany and in wild yellow-necked field mice ( Apodemus flavicollis) at and near the zoo. Ruhugu and rustrela viruses share an identical genomic architecture with rubella virus ^{2, 3} . Amino acid sequences of rubella, ruhugu, and rustrela viruses are moderately to highly conserved within 4 putative B-cell epitopes in the fusion (EI) protein and, in the case of rubella and ruhugu viruses, within two putative T-cell epitopes in the capsid protein ^{4– 6} . Modeling of E1 homotrimers in the post-fusion state predicts similar host-cell membrane fusion capacity for ruhugu and rubella viruses ⁵ . Together, these findings suggest show that some members of the Matonaviridae can cross wide host species barriers and that rubella virus likely had a zoonotic origin. Our findings raise concerns about future zoonotic transmission of rubella-like viruses but open doors for heretofore impossible comparative studies and novel animal models of rubella and congenital rubella syndrome.