Vaccine

A method to identify prime and boost immunogens for use in a B cell lineage-based vaccination protocol comprising:

• i) identifying pairs of variable heavy (VH) and variable light (VL) chain sequences expressed as B-cell receptors by a single cell of clonally related B cells from a subject producing broad neutralizing antibodies (bnAbs), including a pair of VH and VL chain sequences of a mature bnAb,
• ii) inferring from the sequences of step (i), a pair of VH and VL chains of an unmutated ancestor antibody (UA) of the mature bnAb, and one or more pairs of VH and VL chains of likely intermediate antibodies (IAs) of the mature bnAb,
• iii) expressing the pair of VH and VL chains of the UA inferred in step (ii) to produce the UA, and expressing the one or more pairs of VH and VL chains of the one or more likely IAs inferred in step (ii) to produce the one or more likely IAs,
• iv) performing one or more UA binding assays, wherein the binding affinity of the expressed UA of step (iii) for one or more immunogens is determined,
• v) identifying a first immunogen with a binding affinity for the UA determined in step (iv), wherein the first immunogen is identified as a prime immunogen,
• vi) performing one or more IA binding assays, wherein the binding affinity of the one or more expressed likely IAs of step (iii) for one or more immunogens is determined, wherein the one or more immunogens comprises the first immunogen identified as the prime immunogen in step (v), and
• vii) identifying one or more second immunogens with enhanced binding affinity for the one or more likely IAs relative to the first immunogen of step (v), wherein the one or more second immunogens is identified as one or more boost immunogens,
• wherein the first immunogen identified as a prime immunogen has an antigenic structure different than each of the one or more immunogens identified as one or more boost immunogens.