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Characterization of a virus variant produced by L cells persistently infected with lymphocytic choriomeningitis virus
C Stocker1, L Martínez Peralta, T Kratzberg
1Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Universität Hamburg, Germany.
Abstract:
Continuous cultivation of murine L cells infected with lymphocytic choriomeningitis virus strain Armstrong leads to production of L(Arm) cells, which produce a predominantly cell-associated attenuated variant, the L(Arm) virus. The relatively few infectious particles that are released have lost the ability to form plaques on L cells and to cause illness in mice even if inoculated intracerebrally. Based on equal protein M(r)s, antigenicity and protein kinase activity, essentially identical results were obtained for the purified Armstrong and L(Arm) viruses. There was also no difference in production and release of particles with the potential to cause homologous interference. Such particles consisted of two types, one of which was highly susceptible to u.v.-irradiation, the other was highly resistant. In the case of the L(Arm) virus interfering particles, it appears that the u.v.-irradiation-susceptible forms represented infectious virus. Purified L(Arm) virus particles contained considerable quantities of subgenomic forms of (small) S- and (large) L-RNA and their complementary counterparts, which all appeared to be replicated autonomously in an unenriched manner.
Insights
Continuous cultivation of lymphocytic choriomeningitis virus (LCMV) in L cells yields an attenuated variant. This L(Arm) virus produces infectious particles with altered properties, including reduced pathogenicity and altered RNA replication.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Murine L cells infected with lymphocytic choriomeningitis virus (LCMV) strain Armstrong were continuously cultivated.
- This process led to the generation of L(Arm) cells producing an attenuated viral variant.
Purpose of the Study:
- To characterize the properties of the attenuated L(Arm) virus variant.
- To investigate the nature of infectious and interfering particles produced by L(Arm) cells.
Main Methods:
- Continuous cell culture of infected murine L cells.
- Purification and characterization of viral particles (Armstrong and L(Arm) viruses).
- Analysis of protein characteristics (M(r), antigenicity, kinase activity).
- Assessment of plaque-forming ability and pathogenicity in mice.
- UV-irradiation susceptibility assays for interfering particles.
- RNA analysis of purified viral particles.
Main Results:
- L(Arm) virus is predominantly cell-associated and attenuated, with released infectious particles showing reduced plaque formation and pathogenicity.
- Purified Armstrong and L(Arm) viruses showed identical protein M(r)s, antigenicity, and protein kinase activity.
- Both viruses produced homologous interfering particles, with two types differing in UV-irradiation susceptibility.
- UV-susceptible interfering particles of L(Arm) virus appeared to represent infectious virus.
- Purified L(Arm) virus contained abundant subgenomic S- and L-RNA forms and their complements, replicating autonomously.
Conclusions:
- Continuous cultivation of LCMV in L cells generates an attenuated variant with altered biological and molecular properties.
- The L(Arm) virus variant exhibits distinct characteristics in particle association, pathogenicity, and RNA composition.
- The study provides insights into viral attenuation mechanisms and the nature of LCMV RNA replication.