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Growth and release of several alphaviruses in chick and BHK cells
Abstract:
The growth and release of several alphaviruses, including several strains of Sindbis virus (the wild-type strain, the large plaque and small plaque variants of the HR strain, and the HR mutant ts103), Semliki Forest virus(SFV) and Middelburg virus, and of the unrelated rhabdovirus, vesicular stomatitis virus (VSV), have been compared in chick cells and in BHK-21 cells as a function of the culture conditions for the host cell and the ionic strength of the medium. The small plaque strain of Sindbis HR, as well as SFV, grew better in BHK cells, whereas the large plaque strain of Sindbis HR showed a preference for chick cells. Wild-type Sindbis and VSV grew equally well in either cell. The optimum ionic strength for virus production as well as inhibition of virus release into the medium at low ionic strength depended upon both the virus and the host cell. Thus, VSV grown in medium of low ionic strength gave no additional release of virus on incubation with hypertonic medium (minimum effect), whereas ts103 released very little virus without exposure to hypertonic conditions (maximum effect). The viruses could be ordered as follows: minimum effect = vesicular stomatitis virus < Middelburg virus < Semliki Forest virus < Sindbis wt < Sindbis HR (large plaque) < Sindbis HR (small plaque) < Sindbis ts103 = maximum effect. After several passages in culture, chick cells required hypertonic conditions for optimum production and release of Sindbis virus. Furthermore, BHK cells cultured in different media responded differently to ionic strength for virus production and release. These results suggest that there is a charge-dependent stop in the maturation of alpha-viruses, possibly a configurational rearrangement of glycoprotein E2 upon its formation from the precursor PE2, which is sensitive to the ionic strength of the medium, to the composition of the host plasmalemma and to differences in the virus glycoproteins.
Insights
Virus release from host cells depends on ionic strength and cell type. Alphaviruses and rhabdoviruses show varied responses, suggesting a charge-dependent maturation process sensitive to medium conditions and cell interactions.
Area of Science:
- Virology
- Cell Biology
- Biochemistry
Background:
- Alphaviruses and rhabdoviruses exhibit distinct growth characteristics in different cell lines.
- Host cell culture conditions and medium ionic strength significantly influence viral replication and release.
Purpose of the Study:
- To compare the growth and release of alphaviruses (Sindbis virus strains, Semliki Forest virus, Middelburg virus) and vesicular stomatitis virus (VSV) in chick and BHK-21 cells.
- To investigate the impact of host cell culture conditions and medium ionic strength on viral production and release.
Main Methods:
- Comparative analysis of viral growth and release in chick and BHK-21 cells.
- Manipulation of host cell culture conditions and medium ionic strength.
- Observation of viral release patterns under varying osmotic pressures (hypotonic vs. hypertonic).
Main Results:
- Specific Sindbis virus strains (small plaque HR, SFV) preferred BHK cells, while others (large plaque HR) preferred chick cells. Wild-type Sindbis and VSV showed no cell preference.
- Optimal ionic strength for virus production and release varied between virus and host cell types.
- A charge-dependent inhibition of alpha-virus maturation, potentially involving glycoprotein E2 processing, was observed, influenced by ionic strength, host cell membrane, and viral glycoproteins.
Conclusions:
- Viral release is modulated by a complex interplay of virus-specific factors, host cell properties, and environmental conditions like ionic strength.
- The findings suggest a conserved mechanism in alphavirus maturation sensitive to charge and membrane interactions.
- Further research into glycoprotein processing and its environmental sensitivity is warranted.