In Vitro Screening: Lujo Virus – Arenaviridae

Explain what in vitro (Mammalian cell culture) screening is. Why is it important?

In vitro screening is the process through which mammalian cells are nurtured outside the host body in conditions that are fine-tuned to suit the growth requirements of the particular cells. Cells employed in these cultures are obtained from blood. However, only leucocytes can survive in culture. Those cells obtained from a subject are referred to as Primary cells. Since mammalian cells are subject to senescence, researchers have developed immortal cells. These cells are obtained from tumor cells or artificially engineered to extend their lifespan.

The importance of mammalian cell cultures cuts across disciplines. Mammalian cell cultures play a core role in medicine especially in the development of viral vaccines. Furthermore, the biotechnology industry utilizes mammalian cell culture in a myriad of processes, especially in recombinant DNA technology. In the pharmaceutical industry, mammalian cell cultures are utilized in the screening of new drugs for toxicity and efficacy. Other biological products ranging from enzymes to anticancer agents have been developed by utilizing mammalian cell cultures.

Give three examples from primary literature of in vitro screens using viruses within the same family as your assigned virus (Lujo virus – Arenaviridae)

Example 1

Baize, S., et al. 2009. Early and strong immune responses are associated with control of viral replication and recovery in Lassa virus-infected Cynomolgus monkeys. J.Virol. 83:5890-5903.

In vitro stimulation was carried out on the Lassa virus a member of the Arenaviridae to elicit cellular mediated immunity from cells obtained from the Cynomolgus monkeys. This gave the researchers an overview of the determinants of the prognosis of the hemorrhagic fever caused by the Lassa virus.

Example 2

Ank, N., et al. 2006. Lambda interferon (IFN-lambda), a type III IFN, is induced by viruses and IFNs and displays potent antiviral activity against select virus infections in vivo. J Virol. 80:4501-4509.

According to the researchers, various viruses induce the production of cytokines. The researchers set out to identify which viruses induced the production of Type III interferons. To achieve this, they carried out in vitro tests using viruses from different families. Lymphocytic Choriomeningitis Virus (LCMV) from the Arenaviridae family was one of the viruses used. It was demonstrated that Type III interferons were produced against some of the viruses while others did not show any response.

Example 3

Alejandra, T., et al. 2001. Zinc-binding properties of Junín virus nucleocapsid protein. Journal of General Virology. 82:121-128.

Junín virus a member of the Arenaviridae is implicated as the causative agent for Argentine hemorrhagic fever. Researchers set out to confirm the hypothesis that zinc binding by this virus is crucial for its virulence. To this, they carried out in vitro studies using mammalian cell lines to elicit the chemical moiety responsible for zinc binding.

What does it mean for a drug to have low toxicity? How would you screen for your compounds’ toxicity?

A drug is said to have low toxicity if it has a wide therapeutic window. In such cases, the difference in concentration at which the drug is safe and the concentration at which it is toxic is so wide that it is safer over a large range of concentrations. I’ll carry out in vitro tests by testing the compound on isolated mammalian cell cultures to determine the lethal dose of the drug and any observable toxic effects. Thereafter I will proceed to carry out in vivo tests in animal models to map out the toxic profile of the drug.

Work Cited

Ank, Nina, West, Hans, Bartholdy, Christina, Eriksson, Kristina, et al. “Lambda interferon (IFN-lambda), a type III IFN, is induced by viruses and IFNs and displays potent antiviral activity against select virus infections in vivo”. Journal Virology. 80. 9(2006):4501-4509.