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RON2, a novel gene in Babesia bigemina, contains conserved, immunodominant B-cell epitopes that induce antibodies that block merozoite invasion

2019; Cambridge University Press; Volume: 146; Issue: 13 Linguagem: Inglês

10.1017/s0031182019001161

1469-8161

Juan Mosqueda, Mario Hidalgo‐Ruiz, Diana Alexandra Calvo Olvera, Diego Josimar Hernández-Silva, Massaro W. Ueti, Miguel Mercado-Uriostegui, Angelina Rodríguez, Juan Alberto Ramos-Aragon, Rubén Hernández-Ortíz, Shin‐ichiro Kawazu, Ikuo Igarashi,

Toxin Mechanisms and Immunotoxins

Abstract Bovine babesiosis is the most important protozoan disease transmitted by ticks. In Plasmodium falciparum , another Apicomplexa protozoan, the interaction of rhoptry neck protein 2 (RON2) with apical membrane antigen-1 (AMA-1) has been described to have a key role in the invasion process. To date, RON2 has not been described in Babesia bigemina , the causal agent of bovine babesiosis in the Americas. In this work, we found a ron2 gene in the B. bigemina genome. RON2 encodes a protein that is 1351 amino acids long, has an identity of 64% (98% coverage) with RON2 of B. bovis and contains the CLAG domain, a conserved domain in Apicomplexa. B. bigemina ron2 is a single copy gene and it is transcribed and expressed in blood stages as determined by RT-PCR, Western blot, and confocal microscopy. Serum samples from B. bigemina -infected bovines were screened for the presence of RON2-specific antibodies, showing the recognition of conserved B-cell epitopes. Importantly, in vitro neutralization assays showed an inhibitory effect of RON2-specific antibodies on the red blood cell invasion by B. bigemina . Therefore, RON2 is a novel antigen in B. bigemina and contains conserved B-cell epitopes, which induce antibodies that inhibit merozoite invasion.