A process by which a virus improves the virulence of its host for that host's respective host. Common in but not limited to bacteriophages; also occurs in phage-bearing bacteria infecting plants or animals for example. Mechanisms include the expression of factors that modulate a bacterial adhesion to a host cell, spread through host tissues, production of exotoxins or provide protection against host immune defenses.
Source:PMID:22919604,
PMID:8658163,
VZ:3965,
PMID:10913072,
PMID:11553559