A Scientist Visits the Salk School of Science
BHW: Good morning. I am Byron Waksman. I am a professor at New York University and an immunologist. We will talk a lot this year about virus infections and immunity and later about diseases related to the immune system, which I have worked on all my life. This is my assistant. He will introduce himself.
RJW: Good morning. I am Robert Walker. I grew up in upstate New York, near Syracuse. I am a graduate student at NYU, a molecular biologist, studying how proteins are made. After I get a Ph.D., I plan to teach.
BHW: Today we will first talk briefly. Then we plan to hand out some pictures and questions to go with them. You will be divided into groups of three or four, and each group will have 10 minutes to study one of the pictures and try to come up with the answers to the corresponding questions. Finally, there are presentations: One person from each group will speak to the class as a whole for a few minutes, describing the picture (which we will put on the screen while he or she is talking) and answering the questions. Mr. Berkman [the science teacher], Robert Walker and I are available to help you, while you are studying whichever picture you are assigned, and we also may comment during the presentations. Our intention is to be helpful, not to criticize.
Now, to get started: How many of you know what chickenpox is? [Show of hands by essentially all those present.]
How many have actually had chickenpox? [Show of hands by some, usually more than half the class.]
Up until a few years ago, there was another widespread children's infection resembling chickenpox but more severe. It was called smallpox. How many of you have heard of it? Does anyone care to describe it? [Hands, answers, comments.]
Here is a picture of a young child with smallpox [Slide 1]. It used to kill as many as half of the children who became infected. Those who survived had bad scars, especially on their face [Slide 2]. Boys scarred in this way suffered great loss of self-esteem and often had problems all their life. Girls were often so disfigured they could not get married—200 years ago, they and those around them perceived this as a disaster.
An English gentleman, named Edward Jenner, with a house in the country, noticed that the girls on his farm were not pockmarked; they had that beautiful rosy English complexion you read about. He asked about this and learned that they got an infection on their hands from milking the cows, called cowpox; once they got over their cowpox, they would never get smallpox. Here is what cowpox looks like. [Slide 3, Jenner's drawing, below.]
We know that smallpox and cowpox are caused by very closely related viruses. Jenner was seeing an immune reaction, but also he understood that the immune system couldn't tell the two viruses apart. As you know, getting chickenpox doesn't make you immune to measles—those are two viruses that are really distinct. The immune system is very specific: It easily recognizes them as two different things. Anyhow, Jenner tried putting some material from a cowpox sore into the skin of a healthy child and later showed that that child could not get smallpox (or, as we would say: the child was immune to smallpox). How do you suppose he showed that? [Answers, some correct.]
That's right: He actually tried infecting that child with live smallpox. Could we do a human experiment like that today? [no] Good! We certainly couldn't. We have committees of doctors and ministers and ordinary citizens to decide what human experiments are permitted.
[Handout 1, flyer from Jenner Museum.] This handout shows a picture of Jenner putting the cowpox into the little boy, also Jenner's house and garden and a map of the area where he lived in Gloucestershire, England. They made a permanent museum of the house in his honor, because he had made a great discovery.
Now, how many of you speak Spanish? [Some hands.] Does anyone know the Spanish word for "cow?" [Vaca?] That's right. "Vaca" is really the original Latin word—remember Spanish comes from Latin. Medical people used to use Latin and Greek names for all their medical terms, because they didn't want ordinary people to understand what they were saying. So Jenner called his new procedure vaccination after the Latin word for "cow."
It is now 200 years since Jenner discovered vaccination as a way of immunizing against smallpox. People gradually began to use it to protect their children. Yet, less than 50 years ago, there were still lots of cases of smallpox around the world. Look at this! [Slide #4, map of world showing smallpox cases in 1950–55.] There were so many cases—remember, many of the people who got infected died—even though we knew how to vaccinate people and protect them.
Well, finally the World Health Organization, which is based in Geneva, Switzerland, put on a big push in the 1970s to get rid of smallpox by isolating infected individuals and vaccinating everybody who had any contact with them until, at last: [Slide #5, magazine cover announcing "smallpox is dead."] The disease really was conquered as a result of this worldwide effort.
[Question from second row: I read that they are keeping stocks of live virus in two places. Is that true?] Yes, one in the U.S. and one in Russia. Should we be doing this? Is it dangerous? [Lively, brief discussion; question unresolved.]
Let's move on now. Mr. Berkman is distributing the handouts with pictures and questions that you are going to study.
[The science teacher distributes handouts containing nine pictures with accompanying questions to all students. He assigns groups of 3–4 students the task of studying individual pictures and coming up with answers to the corresponding group of questions.]
Students studied the assigned pictures for 10 minutes while the senior scientist continued to list unfamiliar terms. Students gave talks individually or in pairs, representing the small groups. They used a pointer and were asked to describe the assigned picture, projected on the screen. The students had thought of the minimal satisfactory answer virtually every time—and often came up with additional answers that were not anticipated.
Sample question sets and minimal satisfactory answers:
Representative clinical chart of a typical case of smallpox.
Describe course of fever. Up and down.
Are there separate phases? Yes, at least two.
How do these phases relate to skin lesions? (definitions: macule = spot; papule = bump; vesicle = blister; pustule = pimple; crust = scab) High early, then falling, high again during pustular phase, gradually returning to normal.
The decline of epidemic smallpox, 1971–79
Where was the largest reservoir of disease? India.
Why did it disappear so fast? Human disease, no animal reservoir, good vaccine. (These suggestions came from the senior scientist. The students could not answer the question.)
Where were the last cases? Africa, India, U.K. (Laboratory infection!)
What were the keys to success in eradicating smallpox? Will and determination.
» Post Comment