How are Viruses Studied?

by Vincent Racaniello, PhD

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    00:01 Hello and welcome to Viruses. We're going to dig a little bit deeper into this fascinating subject and at the end of today's lectures, you should be able to know how viruses are cultivated and assayed. You should be able to distinguish the seven different types of viral genomes and their structures. And you should appreciate what information is and is not encoded in a viral genome.

    00:32 Let's first start by talking a little bit about how we study viruses. Now if you remember from our introductory lecture that animal viruses were discovered around the end of the 1800s, but for many years these viruses could not be routinely studied in cells in culture. They had to be studied in laboratory animals, and laboratory animals of all sorts were used, some of them are shown here, but as you can imagine, this is not a convenient procedure, plus laboratory animals can differ from experiment to experiment. So it was very important to try and determine how to grow viruses in cells and many scientists worked on that problem. Before 1949, it was not possible to use cells in a consistent and reproducible way to study viruses. But in that year, three scientists, Enders, Weller and Robbins, working in the US, found that they could propagate poliovirus, a human virus, in human cell cultures.

    01:41 Now they happen to use what we call primary cultures from embryonic tissues, but this experiment set a precedent. For the first time, it was possible to propagate a human virus in cell cultures. This was a very important discovery for which these researchers received the Nobel Prize in medicine in 1954.

    02:04 That discovery is with us today. Since 1949, we've been able to study viruses in a variety of cell cultures derived from different sources. For example, we can use primary cell cultures, where the tissue is taken from a source, it's minced up to produce individual cells and then it is put on a plastic layer, in addition covered with medium. So, on the left-hand part of this slide you can see a photograph of primary human foreskin fibroblast cells in culture. Human foreskins are very easy to obtain, because when babies are born, we often remove the foreskin, it's thrown away in the hospital. But if you're interested, you can obtain them and produce primary cells like these. This of course is not so convenient to use on a routine basis, so for that reason we have what we call cell lines and there are two examples of these cell lines shown on this slide; one is a mouse fibroblast cell line, it's called 3T3 and then there is a human epithelial cell line, the famous HeLa cells. Both of these cells are what we call immortal. They grow forever. You can grow them over and over in the laboratory and that makes it a lot easier to do your experiments.

    03:25 Now the negative aspect of using a cell line, is that they are a little bit unusual. They have far too many chromosomes. They are a bit abnormal. Some of them are in fact cancer cells. So if this is a problem for your research, we also have what we call diploid cell lines like the WI-38 cell line, which is derived from human embryonic lung. These have a normal number of chromosomes, they don't live forever, but they do live a long enough time to make your experiments convenient.

    About the Lecture

    The lecture How are Viruses Studied? by Vincent Racaniello, PhD is from the course Viruses.

    Included Quiz Questions

    1. Viruses can grow in cell culture
    2. Viruses cannot replicate without the golgi apparatus
    3. Viruses are autotrophs
    4. The viral envelope does not contain any protein
    5. The viral capsid is made up of carbohydrates

    Author of lecture How are Viruses Studied?

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD

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    not so informative
    By sazzad hoss a. on 14. January 2019 for How are Viruses Studied?

    not detailed and for a introductory vedio should be more explanatory