Serological for screening and Molecular for confirmation.
Screening: A TBRV-specific ELISA kit is commercially available (
Neogen Europe Ltd ). However, this ELISA was found to cross react with other nepoviruses and failed to identify one of six tested strains of TBRV (Harper et al., 2011).
Agdia offers testing services for TBRV in the United States via (
DAS ELISA), but reagents do not appear to be available from Agdia. The ELISA reagents, however, are available from other companies, including
Bioreba, which is represented by Eurofin Labs in the United States. AC Diagnostics, based out of Fayettville, AR, recently began to offer a
DAS ELISA testing kit and reagents for TBRV.
Bioreba also offers a DAS ELISA
testing kit for TBRV The product description mentions that "the virus shows quite some antigenic variation between strains", suggesting that the kit might not detect all isolates of TBRV. Bioreba"s kit uses a mix of antibodies to grapevine and potato virus isolates, and different extraction buffers are recommended depending on the host material.
Confirmation: Work instructions (WI-B-T-G-23 and WI-B-T-G-24) were developed by the CPHST Beltsville Lab. These work instructions were developed using a synthetic target (a mini gene) spiked into healthy plant RNA.
Note: These work instructions require additional validation by CPHST Beltsville using field collected plant samples before work instructions will be made available to the CAPS community.
Detection of Tomato black ring virus (TBRV) using a Multiplex Reverse-Transcription (RT) Conventional PCR (Work Instruction: WI-B-T-G-23)
TBRV RNA2 sequences available in National Center for Biotechnology Information (NCBI) nucleotide databases (NC-004440, AY157944 and X80831) were used to design the virus-specific forward primer PTBRV2f and reverse primer PTBRV486mr, a modified version of the published reverse primer TBRV-sp-a (Digiaro et al. 2007). The TBRV assay targets a segment of the capsid protein gene on RNA2 using TBRV-specific primers (PTBRV2f and PTBRV486mr) multiplexed with Nad5 plant gene-specific primers (Menzel et al., 2002) as an internal control in a two-step RT-PCR using a commercial kit.
Detection of Tomato black ring virus (TBRV) using a Multiplex RT quantitative PCR (qPCR) in a Cepheid SmartCycler (Work Instruction: WI-B-T-G-24)
The TBRV assay targets a segment of the capsid protein gene on RNA2 using TBRV-specific primers (TBRV2f and TBRV4r) and TaqMan FAM probe (TBRV125p), developed by the Beltsville Lab, multiplexed with plant gene (Nad5) specific primers and TaqMan TET probe (Nad5p1) as an internal control in a two-step RT qPCR using a commercial kit.