Using atomic force microscopy imaging and nanoindentation measurements, the effect of the minor capsid proteins pUL17 and pUL25 on the structural stability of the icosahedral Herpes Simplex Virus type 1 capsids was investigated. pUL17 and pUL25 that form the capsid vertex-specific component particularly contributed to the capsid resilience along the 5-fold and 2-fold, but not the 3-fold icosahedral axes. We tested whether deletion of UL17 and UL25 changed the levels of the proteins that assemble in the nucleocapsid by quantitative mass spectrometry.