What you've described is a similar concept to what immunologists call Vectored Immunoprophylaxis (VIP). VIP has been used effectively in vaccination and treatm

What you've described is a similar concept to what immunologists call Vectored Immunoprophylaxis (VIP). VIP has been used effectively in vaccination and treatment of HIV in mouse models [1], and primate trials are ongoing. Essentially this approach entails delivering the gene encoding for an antibody (for example N6 from this paper) directly in a viral vector to cells in the body. This process completely bypasses the traditional physiological vaccination and antibody selection process which may fail to produce a useful antibody such as N6. Instead, the antibody is directly expressed, and secreted from cells that the viral vector infected. Because we know the delivered antibody is effective at targeting the pathogen, these antibodies enable the immune system to home in on the virus in a deterministic way. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3990417/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3990417/