Studies on reovirus type 2: viral interference with UV-inactived virus

Reovirus inhibits poliovirus replication upon superinfection

OBJECTIVE

Viral interference has been demonstrated in different systems, such as the effect of enterovirus infection on live-attenuated oral polio vaccine. In this study, the effect of reovirus which could exist in the human intestinal tract on poliovirus vaccine strains was investigated and could be an important factor to consider in oral polio vaccination.

METHODS

Cells were infected with reovirus, then superinfected with poliovirus. The amount of viral yields was measured by the TCID(50) and plaque assay methods. Polioviral RNA synthesis was studied by real-time RT-PCR and the viral RNA load was calculated. Viral protein synthesis was determined using the techniques of immunoflourescent staining and PAGE followed by the immunoblotting experiment.

RESULTS

Poliovirus superinfection of reovirus-infected cells resulted in inhibition of poliovirus replication. It was found that the inhibitory effect of reovirus was after establishment of its infection (2 h postinfection). There was no competition between the two viruses for cell attachment but poliovirus RNA and protein synthesis were inhibited.

CONCLUSION

Infection of cells with reovirus could interfere with the growth of poliovirus upon superinfection. This phenomenon could be important to consider when using attenuated poliovirus vaccine.

Early cytoplasmic vacuolization of African green monkey kidney cells by SV40

As early as 3--4 hours after infection with SV40 at a high input multiplicity, African green monkey (Cercopithecus aethiops) kidney (AGMK) cells developed cytoplasmic vacuolization. At 10--20 hours after infection, the vacuolization reached its maximal level, then disappeared and SV40 specific cytopathic change followed. This vacuolization developed before the synthesis of the specific T and V antigens. This early cytoplasmic vacuolization (ECV) was prevented by preincubating the virus with specific antiserum, or by heating the virus with MgCl2. The ECV could be induced by UV-irradiated SV40. Addition of metabolic inhibitors had no effect on the induction of the ECV. These results suggest that the capacity to induce the ECV resides in a structural component(s) of SV40 virion and the vacuolization is not associated with the replication of SV40.