Describe how the presentation of a virus antigen on a cell leads to the secretion of antibodies against this viral antigen

3 mark question - remember to use key words/phrases the examiner will be looking for to give you the marks. Be concise and specific in your answer - make it as easy as possible for the examiner.
Helper T cells bind to the antigen on the antigen-presenting phagocyte (1). This helper T cell stimulates a specific B cell to undergo clonal selection (2) and these cells then form plasma cells that release antibodies specific to the viral antigen that was presented (3).