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Host cell-dependent homologous interference in lymphocytic choriomeningitis virus infection
1Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Universität Hamburg, Federal Republic of Germany.
Abstract:
The generation of virus progeny as well as transcription, translation, and replication of the viral small RNA (S-RNA), which codes for the nucleoprotein (NP) and the glycoprotein precursor (GPC), was followed in L and MDCK cells after infection with multiplicities (m.o.i.) ranging from 0.01 to 100. In L cells, the yields of both plaque-forming units and interfering particles varied inversely with the m.o.i. Northern blot analysis revealed that early after infection with high multiplicity NP-mRNA was present, but later few or no signals of any specificity were registered. After low m.o.i. the results were negative at 8 hr, but large quantities of mRNAs for NP and GPC as well as viral genomic S-RNA and genomic-sized complementary S-RNA had been synthesized at 48 hr. In MDCK cells, throughout the range of m.o.i. both entities attained lower levels and most were generated at m.o.i. one. The degree of hybridization correlated roughly with the quantity of infectious virus to which the cells had been exposed. In the cells of both lines the NP-mRNA corresponded to the synthesis of its translation product, but once produced, most of it appeared to be retained in the phosphorylated form. We assume that the homologous interference seen in L cells after infection with high m.o.i. results from a host-dependent inhibition of viral transcription and replication mediated by NP.
Insights
High multiplicity virus infection inhibits viral RNA synthesis in L cells, while low multiplicity promotes it. Nucleoprotein (NP) may mediate this host-dependent interference.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Viral small RNA (S-RNA) replication, transcription, and translation are crucial for virus progeny generation.
- Nucleoprotein (NP) and glycoprotein precursor (GPC) are key viral proteins encoded by S-RNA.
- Understanding viral replication dynamics in different cell types and multiplicities is essential.
Purpose of the Study:
- To investigate the impact of varying multiplicities of infection (m.o.i.) on viral S-RNA replication and protein synthesis in L and MDCK cells.
- To elucidate the role of NP in host-dependent homologous interference during viral infection.
Main Methods:
- Infection of L and MDCK cells with a range of viral multiplicities (0.01 to 100).
- Quantification of plaque-forming units and interfering particles.
- Northern blot analysis to detect viral S-RNA, genomic S-RNA, complementary S-RNA, and NP-mRNA.
- Assessment of NP translation product and its phosphorylation state.
Main Results:
- In L cells, viral yields decreased with increasing m.o.i., and high m.o.i. led to early NP-mRNA but later loss of viral RNA signals.
- Low m.o.i. in L cells resulted in significant synthesis of NP-mRNA, GPC-mRNA, and viral S-RNAs by 48 hours.
- MDCK cells showed lower viral yields across m.o.i. ranges, with peak production at m.o.i. one, correlating with infectious virus exposure.
- NP-mRNA correlated with NP synthesis, with most NP retained in a phosphorylated form in both cell lines.
Conclusions:
- Homologous interference in L cells at high m.o.i. is likely due to host-dependent inhibition of viral transcription and replication mediated by NP.
- Viral replication efficiency is dependent on both cell type and multiplicity of infection.
- Phosphorylation of NP may play a role in regulating viral gene expression or replication.