Cross-linked cationic particles 150-300 nm in diameter have been synthesized via single-stage emulsifier-free copolymerization of methyl methacrylate and 2-aminoethyl methacrylate hydrochloride in the presence of cross-linking agents (ethylene glycol dimethacrylate and N,N'-methylenebisacrylamide). Factors that enable one to control the morphology and polydispersity of the resulting particles have been determined. It has been shown that the dispersions of the particles are aggregatively stable in physiological solutions and after the sorption of biologically active molecules. The synthesized particles can be used for efficient revealing tick-borne encephalitis virus via latex agglutination reaction, with the analysis time being no longer than 10 min.