Rapid detection of equine infectious anaemia virus nucleic acid by insulated isothermal RT-PCR assay to aid diagnosis under field conditions

Background: Control of equine infectious anaemia (EIA) currently depends on serological diagnosis of infected equids. However, recently infected equids may not produce detectable anti-EIAV antibodies up to 157 days post infection and so present a high transmission risk. Therefore, direct nucleic acid detection methods are urgently needed to improve EIAV surveillance and management programs in counties where the disease is endemic. Objectives: To evaluate a field-deployable, reverse transcription-insulated isothermal PCR (RT-iiPCR) assay targeting the conserved 50 untranslated region (50 UTR)/exon 1 of the tat gene of EIAV. Study design: The analytical and clinical performance of the newly developed EIAV RT-iiPCR was evaluated by comparison with a EIAV real-time RTPCR (RT-qPCR) along with the AGID test. Methods: Analytical sensitivity was determined using in vitro transcribed RNA containing the target area of the 50 UTR/tat gene and samples from two EIAV-positive horses. Specificity was verified using nine common equine viruses. Clinical performance was evaluated by comparison with EIAV RT-qPCR and AGID using samples derived from 196 inapparent EIAV carrier horses. Results: EIAV RT-iiPCR did not react with other commonly encountered equine viruses and had equivalent sensitivity (95% detection limit of eight genome equivalents), with a concordance of 95.41% to conventional EIAV RT-qPCR. However, the RT-qPCR and RT-iiPCR had sensitivities of 43.75 and 50.00%, respectively, when compared to the AGID test. Main limitations: Low viral loads commonly encountered in inapparent EIAV carriers may limit the diagnostic sensitivity of RT-PCR-based tests. Conclusions: Although EIAV RT-iiPCR is not sufficiently sensitive to replace the current AGID test, it can augment control efforts by identifying recently exposed or “serologically silent” equids, particularly as the latter often represent a significant transmission risk because of high viral loads. Furthermore, the relatively low cost and field-deployable design enable utilisation of EIAV RT-iiPCR even in remote regions.

Bibliographic Details

Main Authors:	Cook, R.F., Barrandeguy, Maria Edith, Lee, Pei-Yu Alison, Tsai, Chuan-Fu, Shen, Yu-Han, Tsai, Yun-Long, Chang, Hsiao-Fen G., Wang, Hwa-Tang Thomas, Balasuriya, Udeni B.R.
Format:	info:ar-repo/semantics/artículo biblioteca
Language:	eng
Published:	Wiley 2018
Subjects:	Caballos, Virus de los Animales, Horses, Equine Infectious Anaemia, Diagnosis, Diagnóstico, Anemia Infecciosa Equina, PCR, Animal Viruses, Equinos, Insulated Isothermal RT-PCR, Point-of-Need Testing,
Online Access:	http://hdl.handle.net/20.500.12123/4481 https://www.onlinelibrary.wiley.com/doi/10.1111/evj.13032 https://doi.org/10.1111/evj.13032
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