  In this paper, we show that $\sigma$-involutions associated to extendable
c=4/5 Virasoro vectors generate a 3-transposition group in the automorphism
group of a vertex operator algebra (VOA). Several explicit examples related to
lattice VOA are also discussed in details. In particular, we show that the
automorphism group of the VOA $V_{K_{12}}^{\hat{\nu}}$ associated to the
Coxeter Todd lattice $K_{12}$ contains a subgroup isomorphic to
${}^+\Omega^{-}(8,3)$.
