Verification of serological relationship between two phylogenetically related peanut-infecting Tospovirus species

Abstract

Based on the serological relationships of nucleocapsid proteins (NPs), a tospovirus species can be classified as a member of a serogroup or a distinct serotype, which greatly helps virus identification and disease diagnosis. Recent studies reported that distinct tospovirus species sharing above 51.8 % amino acid (aa) identity in their NPs may be serologically related. Two phylogenetically related peanut-infecting tospovirus species, Peanut chlorotic fan-spot virus (PCFV) in Taiwan and Peanut yellow spot virus (PYSV) in India, were previously considered as distinct serotypes, since no serological relationship has been established. To verify the serological relationship of PCFV and PYSV, the NP of PCFV was purified from leaf tissues of the infected Chenopodium quinoa plants and used to produce polyclonal antiserum (RAs-PCFV NP) and a monoclonal antibody (MAb-PCFV NP). Polyclonal antiserum to the bacterially expressed NP of PYSV (RAs-PYSV NP) was also prepared. RAs-PCFV NP reacted with the homologous PCFV NP and the bacterial-expressed PYSV NP and tissue extracts of PYSV-infected plants. Reciprocally, RAs-PYSV NP reacted with the homologous bacterial-expressed PYSV NP and the tissue extracts of PYSV-infected or PCFV-infected plants. In addition, MAb-PCFV NP reacted only with the tissue extracts of PCFV-infected plants. Our results demonstrate that PCFV NP is serologically related to PYSV NP and they should be classified as members of a unique serogroup.