Identification and genetic characterization of hepacivirus and pegivirus in commercial equine serum products in China

Abstract

Equine hepacivirus (EqHV), equine pegivirus (EPgV) and Theiler’s disease-associated virus (TDAV) are three novel equine viruses in the family Flaviviridae. EqHV and EPgV have been identified to circulate in the equine population worldwide, whereas TDAV has not been detected in equines since the first reported case. To date, no studies have focused on investigating EqHV, EPgV and TDAV in commercial equine sera or equine blood products in China. Considering the potential threat of EqHV, EPgV and TDAV to biosecurity and considering their possible influences on research results, equine sera for cell culture propagation and pregnant mare serum gonadotropin (PMSG) were purchased from different companies in China and investigated for EqHV, EPgV and TDAV in this study. By performing nested PCR or two rounds of PCR targeting the viral NS3 gene, four serum samples were confirmed to be EqHV-, EPgV-, or TDAV-RNA positive; all of the PMSG samples were negative for these three viruses. Subsequent sequencing results indicated that the serum samples contained multiple viral variants of EqHV, EPgV or TDAV, and a genetic analysis based on the partial NS3 gene of the three equine viruses was performed. Our study is the first to confirm the presence of EqHV, EPgV and TDAV in equine sera for cell culture propagation that is commercially available in China and provides the first demonstration of the presence of TDAV in China.

First description of Theiler's disease‐associated virus infection and epidemiological investigation of equine pegivirus and equine hepacivirus coinfection in Brazil

“…Sequencing and phylogenetic analysis were performed with all TDAV nucleotide sequences available in the GenBank, composed of isolates from commercial equine serum (Lu et al, ; Lu, Sun, et al, ; Postel et al, ), except for the reference , which was isolated from an infected horse (Chandriani et al, ). EPgV sequences also originated from commercial equine serum, and three field isolates (Lu et al, ; Postel et al, ) were included in the analysis. TDAV isolates presented an identity range of 88%–91% with the reference .…”

“…The infection rate and the detection of EPgV RNA in all categories investigated suggest that EPgV is enzootic in Brazil, corroborating other reports from Europe and USA (Kapoor, Simmonds, Cullen, et al, ; Lyons et al, ). Concomitant detection of EPgV and EqHV‐RNA was described in China in all three EPgV‐RNA positive animals (Lu, Sun, et al, ), in one experimental study (Pfaender, Cavalleri, et al, ) and in equine‐derived commercial sera (Lu et al, ; Postel et al, ). Here, we report that 18.3% of the EPgV RNA‐positive animals were coinfected with EqHV.…”

“…Additionally, the recommendation is to administer tetanus antitoxin (obtained from hyperimmune equine plasma) to all neonates as a prophylaxis measure (O'Brien, ). Thus, horses may be exposed to EPgV, TDAV or EqHV during the first days after birth through the administration of equine‐derived products, which are prone to contamination (Lu et al, ; Postel et al, ). In adult horses, subsequent virus exposure can be defeated due to previous contact, as seen for other equine infections such as equine herpesvirus 1 (EHV‐1) and EqHV (Perkins & Wagner, ; Pfaender et al, ).…”

“…After the description of the TDAV outbreak in 2013 (Chandriani et al, ), TDAV‐RNA was detected in equine commercial serum from China and USA (Lu, Huang, & Li, ; Lu et al, ), but all attempts to detect infected horses were unsuccessful (Akari, Iwasaki, Yoshida, & Iijima, ; Lu et al, ; Lyons et al, ; de Souza et al, ; Tomlinson et al, ). In this study, we demonstrated for the first time the detection of TDAV RNA‐positive horses outside the USA without any clinical signs.…”

“…As a consequence, equine‐derived products were considered a potential source of virus infection and spread. Additionally, the presence of virus contaminants in equine‐derived products used in the bioindustry of human medical products and biomedical research was highlighted as a biosecurity issue (Lu et al, ; Postel et al, ).…”