  Multiparticle extension of a higher-spin algebra $l$ is introduced as the Lie
superalgebra associated with the universal enveloping algebra $U(l)$. While
conventional higher-spin symmetry does not mix $n$-particle states with
different $n$, multiparticle symmetries do so. Quotients of multiparticle
algebras are considered, that act on the space of $n$-particle states with
$0\leq n\leq k$ analogous to the space of first $k$ Regge trajectories of
String Theory. Original higher-spin algebra is reproduced at $k=1$. Full
multiparticle algebras are conjectured to describe vacuum symmetries of
string-like extensions of higher-spin gauge theories. Relation of the
multiparticle algebras with 3d current operator algebras is described. The
central charge parameter, to be related to the parameter ${\mathcal N}$ in
$AdS/CFT$ correspondence, enters via the definition of supertrace. Extension to
higher $p$-brane-like symmetries is introduced inductively.
