Viruses as toxins

Cell surface effects of human immunodeficiency virus

“…The purpose of this model is to define the potential roles of individual viral envelope and cell surface molecules in cell killing processes. This model borrows heavily from previous models of cell-cell fusion and cell surface-mediated killing by other fusogenic and/or lytic viruses (37)(38)(39)(40)(41)(42)(43), and is discussed in subsequent sections. Because HIV readily establishes persistent infections, an important feature of the proposed model, which distinguishes it from earlier models, is to identify alternative routes to the establishment of persistently-infected cells.…”

“…Fusogenic Sendai virus has been reported to induce changes in the plasma membrane which result in alterations in Na § and K § flux, the net effect of which is an entry of water and osmotic cell swelling (39)(40)(41)(42)(43)(44). The alterations in ion fluxes have been grouped with other "toxin-like" effects of viruses, because they are reminiscent of the action of certain toxins such as the bee venom protein melittin (43). Moreover, it has been proposed that osmotic swelling is the force which initiates or drives cell-cell fusion events (42, but see also 43,44).…”

“…The alterations in ion fluxes have been grouped with other "toxin-like" effects of viruses, because they are reminiscent of the action of certain toxins such as the bee venom protein melittin (43). Moreover, it has been proposed that osmotic swelling is the force which initiates or drives cell-cell fusion events (42, but see also 43,44). As proposed in the model, it is possible that osmotic cell swelling induced by HIV may be involved in cell-cell fusion events (Fig.…”

“…Certain fusogenic viruses, such as early-harvest Sendai virus do not cause alterations in intracellular ion levels or cell swelling and therefore do not induce the formation of stable binucleate cells (41). The changes in intracellular ion levels induced by fusogenic viruses such as late harvest Sendai virus are usually transient in nucleated cells and may be reversed by cellular homeostatic mechanisms (43). Unlike the case with Sendai virus, however, it appears that cell swelling induced by HIV is irreversible in the majority of infected cells.…”

“…Alterations in intracellular concentrations of Na § and/or K § are also observed during cytolytic infections by picornaviruses (49,50), alphaviruses (51)(52)(53), coronaviruses (56), rhabdoviruses (57), adenoviruses (58), herpesviruses (Koch et al, in preparation) and during retrovirus transformation (59,60). The mechanism for inducing changes in ion flux during lytic infections by certain of these lytic viruses involves inhibition of ion transport systems (51), and thus appears to be distinct from the "toxin-like" effects of fusogenic viruses such as paramyxoviruses (43). It has been suggested that alterations in the intracellular concentration of monovalent cations may be involved in the shutoff of host protein synthesis by certain lyric viruses (37,49,51).…”