Site 1, located at the GH loop and carboxy terminus of VP1, includes VP1C144, 148, 150, and 208

Site 1, located at the GH loop and carboxy terminus of VP1, includes VP1C144, 148, 150, and 208. Additionally, the vulnerability of VLPs prompted us to assess another diagnostic antigen: unprocessed polyprotein P1. Therefore, we established and evaluated the performance of blocking ELISA (bELISA) systems based on VLPs and P1, pairing them with Q10E, Flurandrenolide P11A, S11B, and the non-neutralizing TSG MAb as tracers. The results indicated that the VLP paired with Flurandrenolide S11B demonstrated the highest correlation with the SN titers (R2 = 0.8071, = 63). Excluding weakly positive serum samples (SN = 16C32, = 14), the sensitivity and specificity were 95.65% and 96.15% (kappa = 0.92), respectively. Additionally, the P1 pairing with Q10E also demonstrated a high correlation (R2 Flurandrenolide = 0.768). We also discovered that these four antibodies had steric effects on one another to varying degrees, despite recognizing distinct antigenic sites. This finding indicated that MAbs as tracers could not accurately detect specific antibodies, possibly because MAbs are bulky compared to a protomeric unit. However, our results still provide convincing support for the application of two pairs of bELISA systems: VLP:S11B-HRP and P1:Q10E-HRP. Keywords: foot-and-mouth disease virus, virus-like particles, blocking ELISA, monoclonal antibodies 1. Introduction Foot-and-mouth disease virus (FMDV) is highly contagious and affects all susceptible cloven-hoofed animals globally. In addition to the lack of cross-protection among the seven serotypes (O, A, C, Asia1, SAT1, SAT2, Rabbit Polyclonal to EGR2 and SAT3), restrictions on the import of animal products are very strict, particularly those in FMDV-free countries. A facility with a high biosafety level is also required to handle live FMDV, which carries the potential risk of viral leakage. An effective countermeasure against FMDV outbreaks is blanket vaccination with selected strains followed by serum neutralization (SN) tests to determine the protective antibody response [1,2]. However, both inactivated vaccine production and the SN test are highly restricted to high-level biosafety laboratories. In 1997, a devastating FMDV outbreak resulted in tremendous economic loss in Taiwan. The virus strain, O/TW/97 (O/97), was characterized by porcinophilic activity [3]. Following the guidelines of the OIE (Office International des Epizooties/World Organisation for Animal Health), mandatory vaccination with inactivated vaccines made using three strainsO 4174, O1 Campos, and O1 Manisawas recommended by Flurandrenolide the World Reference Laboratory based on an evaluation of r1 values greater than 0.3 [4] immediately following the outbreak. The FMDV strain O/98, a homologue of O/97, was produced and recognized as the vaccine strain later in Taiwan. After blanket vaccination and surveillance, O/Penghu/2012 was the last isolated virus from this series of FMD cases. In 1999, another virus strain was isolated in Kinmen, an archipelago far off the western coast of Taiwan. It was named O/TW/2/99 and classified as the PanAsia topotype, which is separate from Cathay O/TW/97 [5,6]. The Flurandrenolide FMD eradication campaign lasted until 2020, when Taiwan was recognized as an FMDV-free country by the OIE. FMDV is non-enveloped and consists of a single-stranded positive-sense RNA genome surrounded by a densely packed icosahedral protein shell. The shell comprises 60 copies of a protomer with four capsid proteins, VP1 to VP4, where VP4 is located on the inner side of the virion. FMDV targets host cell receptors, including integrins (v1, v3, v6, and v8), heparan sulfate, and JMJD6, for viral entry [7,8]. However, protective antibodies could effectively block the interaction between virions and receptors to neutralize the virus. Based on MAb escape mutant studies, five neutralizing sites have been described for serotype O. Site 1, located at the GH loop and carboxy terminus of VP1, includes VP1C144, 148, 150, and 208. The critical residues of site 2 are VP2C70, 71, 72, 73, 75, 77, 131, and 191. The residues in site 3 include VP1C43 and.