In vitro RVA fluorescent focus reduction assay using VHH antibodies.

A fourfold dilution of each VHH clone (3B2 VHH, derived from llamas vaccinated with VP6 from RVA strain C486 -G6P[1]I?-,or non-related VHH nanoAb) was mixed with an equal volume of RVA containing 100 focus forming units (FFU) of each strain. The numbers represent the minimum VHH concentration that reduced >80% of the number of fluorescent focus forming units (FFU) of each RVA strain. Neg = no neutralizing activity was observed at the highest concentration tested (62.50 µg VHH/ml). The G-type, P-type and I-type of RVA strains is clarified in brackets next to each strain name (according to [91]).