Supplementary MaterialsTable_1. mAbs, 13 mAbs demonstrated intra-type broadly neutralizing activity against the three topotypes of FMDV serotype O (ME-SA, SEA, and Cathay topotypes). Moreover, all these intra-type broadly neutralizing antibodies competed with sera from FMDV infected or vaccinated cattle, which indicates their binding to native dominant epitopes, as revealed by a blocking ELISA. We further analyzed the germline V(D)J gene usage of the 55 FMDV-specific mAbs and found cattle IgG antibodies containing ultralong HCDR3 were exclusively restricted to usage of the germline gene segment VH 1-7*02. In addition, the restricted germline gene segments of VH 1-7*02 and VL1-47*01 or 1-52*01 pairing were observed in all IgG antibodies with ultralong HCDR3. Furthermore, antibodies with longer HCDR3 were more inclined to display FMDV-neutralizing activity. This study presents a novel method for screening FMDV-specific cattle mAbs which then provide the most useful tools for studying FMDV antigenic structure and variation. in the Picornaviridae, and appears as seven serotypes (i.e., O, A, C, Asia1, SAT1, SAT2, and SAT3) and several topotypes, with uneven geographic distributions. FMDV serotype O has been a major threat to animal husbandry in recent years in China. Four lineages in the three topotypes of FMDV type O, namely, Cathay, Middle East-South Asia (ME-SA), and South-East Asia (SEA) topotypes, are introduced and currently circulating in China, which makes the situation rather complicated. Antigenic variation among these topotypes has been investigated in recent years (1, 2). However, detailed differences in antigenic structure of these topotypes are still not delineated. Monoclonal antibodies (mAbs) recognizing neutralizing epitopes could provide important keys to the basis of this antigenic variation. There is good evidence that humoral Beta Carotene responses play a major role in protection against FMDV infection in natural hosts (3, 4). As a natural host of FMDV, cattle have a distinct composition of immunoglobulin (Ig) repertoire compared to other vertebrates which display restricted lengths of the third heavy chain complement determining regions (HCDR3s) with an average of 12C16 amino acids (aa) in length (5). However, cattle produce antibodies containing HCDR3s with an average length of 26 aa, including an ultralong subset that can exceed 60 aa (6, 7). The proportions of kappa () and lambda () light chains in cattle Ig are 5 and 95%, respectively, whereas those of rodents are 95 and 5%, respectively (8). These unique characters of Ig sequences make cattle a promising host for producing high avidity and broadly neutralizing antibodies Beta Carotene (bnAbs), exemplified by the rapid elicitation of bnAbs to HIV by immunization of cattle; these bnAbs contained ultralong HCDR3s that were responsible for their serological breadth and potency (9). However, it is currently unknown whether the ultralong HCDR3s are responsible for their high avidity and broadly Beta Carotene virus neutralization against FMDV. Up to now, monoclonal antibodies (mAbs) selected from mouse hybridomas have been extensively used to investigate the antigenic profile of Beta Carotene FMDV. As revealed by these mouse mAbs, five functionally-independent neutralizing antigen sites (3C7) have been identified on the capsid surface of FMDV serotype O. Site 1 is linear and trypsin sensitive, which encompasses the G-H loop and the C terminus of VP1, with critical residues at positions 144, 148 and 150, and 208 that affect antibody binding. However, other identified sites (i.e., sites 2C5) are all conformational and trypsin resistant. Site 2 is Beta Carotene defined by mutations in the VP2 B-C or E-F loops, involving critical aa residues at positions 70C73, 75, 77, and 131. Critical residues at positions 43 and 44 within the VP1 B-C loop, with position 58 within the VP3 B-B knob donate to site 3 and site 4, respectively. Site 5 contains a minimum of a functionally 3rd party neutralizing epitope which involves a particular mutation at placement 149 within the G-H loop of VP1, that is specific from site 1 despite area of the G-H loop can be encompassed (10C14). Recently, a fresh neutralizing epitope which involves the positioning 192 of VP2 in the 3-collapse axis was reported (15). FMDV serotype O particular cattle mAbs chosen from Rabbit Polyclonal to OR2W3 a mouse cattle hetero-hybridoma had been utilized to evaluate antigenic features described by mouse mAbs, and these cattle mAbs understand identical.