Development and characterization of novel chimeric monoclonal antibodies for broad spectrum neutralization of rabies virus

<div><p>Current post-exposure prophylaxis for rabies virus infection has several limitations in terms of supply, cost, safety, and efficacy. Attempts to replace human or equine rabies immune globulins (HRIG or ERIG) have been made by several companies and institutes. We developed potent monoclonal antibodies to neutralize a broad spectrum of rabies viruses by screening hybridomas received from the U.S. Centers for Disease Control and Prevention (CDC). Two kinds of chimeric human antibodies (chimeric #7 and #17) were constructed by cloning the variable regions from selected hybridomas and the constant region of a human antibody. Two antibodies were bound to antigenic site III and I/IV, respectively, and were able to neutralize 51 field isolates of rabies virus that were isolated at different times and places such as Asia, Africa, North America, South America, and Australia. These two antibodies neutralize rabies viruses with high efficacy in an <i>in vivo</i> test using Syrian hamster and mouse models and show low risk for adverse immunogenicity.</p></div

Supernatant neutralizing activity of each hybridoma clone against CVS-11 virus.

<p>Supernatant neutralizing activity of each hybridoma clone against CVS-11 virus.</p

The affinity of chimeric MAbs #7, #17 and HRIG for RABV G protein.

<p>Chimeric MAbs #7, #17 and HRIG were incubated in plates coated with 1 μg/mL RABV G protein, and the concentration of each antibody was indicated on the x-axes. Binding to the RABV G protein was expressed as an OD value detected at 450nm. The dots and lines represent the means and standard deviations, respectively, from three independent experiments.</p

Epitope mapping study by SPR assay.

<p>SPR experiments were performed by injecting chimeric MAbs #7 and #17 (1 μM). The time in seconds (x-axis) is plotted against the RU (y-axis). RU levels are indicated for each injected antibody. (a) Injection order: chimeric MAb #17 -> #7. (b) Injection order: chimeric MAb#7 -> #17.</p

Characterization of chimeric MAbs#7 and #17 escape viruses^a.

<p>Characterization of chimeric MAbs#7 and #17 escape viruses<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186380#t003fn001" target="_blank">^a</a>.</p

Anti- RABV MAbs protect mice against lethal RABV infection.

<p>Anti- RABV MAbs protect mice against lethal RABV infection.</p

Summary of T cell activation assay.

<p>Summary of T cell activation assay.</p

The number of T cell proliferative responses detected at four time points.

<p>T cell proliferation was assessed by [³H]-thymine uptake on days 5, 6, 7, and 8 after incubation with the antibodies, and the number of positive responders was plotted.</p

Established MAbs protect hamsters against lethal RABV infection.

<p>Syrian hamsters were divided into four groups (n = 12 in each group) and a MICLD₅₀ of RABV RV342 from China was injected 1 day before antibody treatment. HRIG and chimeric MAbs #7 and #17 were administered, and animals were monitored daily.</p