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Infectivity titration of guinea-pig inclusion conjunctivitis agent in irradiated McCoy cells
Abstract:
Estimation of the infectivity of the agent of guinea-pig inclusion conjunctivitis for irradiated McCoy cells, assayed as inclusion-forming units, was influenced by the age of cells after irradiation, the maturation time of the inclusions, the centrifugal force and the centrifugation temperature. Agent passaged through irradiated McCoy cells or guinea-pig conjunctivae showed a greater capacity to infect irradiated McCoy cells without centrifuging than agent grown in a chick embryo. The nature of the change and the mechanism of infectivity enhancement by centrifuging are discussed.
Insights
The infectivity of guinea-pig inclusion conjunctivitis agent was influenced by cell age, maturation time, and centrifugation. Agent grown in McCoy cells or guinea-pig conjunctivae showed higher infectivity than when grown in chick embryos.
Area of Science:
- Microbiology
- Cell Biology
- Ophthalmology
Background:
- Guinea-pig inclusion conjunctivitis (GPIC) is an ocular infection caused by Chlamydia psittaci.
- McCoy cells are commonly used for propagating Chlamydial agents.
- Understanding factors affecting Chlamydial infectivity is crucial for diagnosis and research.
Purpose of the Study:
- To estimate the infectivity of the GPIC agent for irradiated McCoy cells.
- To investigate factors influencing infectivity, including cell characteristics and processing methods.
- To compare infectivity of agent passaged through different hosts.
Main Methods:
- Infectivity was assayed as inclusion-forming units (IFUs) in irradiated McCoy cells.
- Variables tested included cell age post-irradiation, inclusion maturation time, centrifugal force, and centrifugation temperature.
- Agent infectivity was compared after passage through irradiated McCoy cells, guinea-pig conjunctivae, or chick embryos.
Main Results:
- Cell age, maturation time, centrifugation force, and temperature significantly influenced GPIC agent infectivity.
- Agent passaged through irradiated McCoy cells or guinea-pig conjunctivae demonstrated enhanced infectivity for McCoy cells compared to agent grown in chick embryos.
- Centrifugation further enhanced infectivity, with specific parameters yielding optimal results.
Conclusions:
- The infectivity of the GPIC agent is modulated by host cell conditions and experimental procedures.
- Passaging the agent in specific hosts (McCoy cells, guinea-pig conjunctivae) enhances its subsequent infectivity.
- Centrifugation plays a key role in optimizing the assay for Chlamydial infectivity.