Table 1. Estimates of the main geometric and elastic properties of different non-enveloped empty viral capsids.

The Young’s modulus $E$ has been evaluated from AFM nanoindentation experiments (Mateu, 2012; Michel et al., 2006; Ivanovska et al., 2007; Sae-Ueng et al., 2014) and, for SV40, from the experimental spring constant (van Rosmalen et al., 2018) using the standard thin shell formula $k=2.25E{h}^2/R$ (Ivanovska et al., 2004). The 2D Young’s Modulus was calculated as $Y=Eh$; the effective diameter of the capsomers as (Santolaria, 2011) $\sigma =R/\sqrt{\frac{5\sqrt{3}}{\pi }}\left(T+\frac{1}{\sqrt{3}}cot\left(\frac{\pi }{5}\right)-1\right)$, where $T$ is the triangulation number; the line tension as (Luque et al., 2012) $\lambda =\frac{2{ϵ}_0}{\sqrt{3}\sigma }$ considering a typical binding energy ${ϵ}_0\approx 10k_{B}T$; and the FvK number as ${\displaystyle \gamma =12(1-{\nu }_p^2)(R/h{)}^2}$, with ${\displaystyle {\nu }_p=0.3}$ (Buenemann and Lenz, 2008).

Virus	T-number	Diameter (nm)	Thickness h (nm)	E (Gpa)	Y (N/m)	σ (nm)	Scaled line tension λ	Föppl-von Karman γ
CCMV	3	28	3.8	0.14	0.53	5.9	0.00107	148
λ Procapsid	7	50	4.0	0.16	0.64	6.8	0.000436	427
λ Capsid	7	63	1.8	1.0	1.8	8.6	0.0000976	3344
SV40	7	45	6.0	0.033	0.2	6.1	0.00174	152