For example, the tightly packed rod structure of the tobacco mosaic virus makes for unstable placement of peptides (chains of amino acids shorter than full proteins), whereas the filamentous BaMV has gaps that can contain exogenous proteins, giving it greater room for modification.
以「菸草嵌紋病毒」為例，直桿狀排列緊密的結構，置放「胜？」（一種短片段氨基酸）時不易穩定；反倒是長絲狀的竹嵌紋病毒，有空間容納外源蛋白，較有改造的彈性。