The history of vaccination
A very early form of vaccination known as variolation was developed several thousand years ago in China. It involved the application of materials from smallpox sufferers in order to immunize others. In 1796 Edward Jenner developed a safe method, using cowpox to successfully immunize a young boy against smallpox, and this practice was widely adopted. Vac- cinations against other viral diseases followed, includ- ing the successful rabies vaccination by Louis Pasteur in 1886. The nature of viruses however was not clear to these researchers.
In 1892 Dimitri Ivanovski showed that a disease of tobacco plants, tobacco mosaic disease, could be transmitted by extracts that were passed through filters fine enough to exclude even the smallest known bacte- ria.
In 1903 it was suggested for the first time that transduction by viruses might cause cancer. Such an oncovirus in chickens was described by Francis Pey- ton Rous in 1911; it was later called Rous sarcoma vi- rus 1 and understood to be a retrovirus. Several other cancer-causing retroviruses have since been described.
While plant viruses and bacteriophages can be grown comparatively easily, animal viruses normally require a living host animal, which complicates their study immensely. In 1931 it was shown that influenza virus could be grown in fertilized chicken eggs, a method that is still used today to produce vaccines. In 1937, Max Theiler managed to grow the yellow fever virus in chicken eggs and produced a vaccine from an attenuated virus strain; this vaccine saved millions of lives and is still being used today.
The first virus that could be crystalized and whose structure could therefore be elucidated indetail
was
tobacco mosaic virus (TMV), the virus that had been studied ear- lier
by Ivanovski and Beijerink. In 1935, Wendell Stanley achieved its
crystallization for electron micros- copy and showed that it remains
active even after crystallization.
Clear X-ray diffraction pictures of the crystallized vi- rus were obtained by Bernal and Fankuchen in 1941.
In 1975 the functioning of oncoviruses was clari- fied considerably. Until that time, it was thought that these viruses carried certain genes called oncogenes which, when inserted into the host's genome, would cause cancer.
A worldwide vaccination campaign led by the UN World Health Organization resulted in the eradi- cation of smallpox in 1979.
Make 15 sentences covering the wholetext.
Draw a line of history and point all virolo-gists onit.
E.
Jenner 1796
Translate the sentences into English using thewords youlearned.
Человек на протяжении всей жизни подвер- гается опасности заразиться и заболеть какой-либо вируснойинфекцией.
Размножаясь, вирусы истощают клеточные ресурсы, глубоко нарушают обмен веществ, и, в конечном счёте, являются причиной гибели кле- ток.
По своему строению и свойствам вирусы занимают промежуточное место между сложней- шими химическими веществами (полимерами, макромолекулами) и простейшими организмами (бактериями).
Долгое время полагали, что вирусы вызы- вают острые массовые заболевания. К настоящему времени накоплено много доказательств того, что вирусы являются причиной и различных хрониче- ских болезней, длящихся годами и даже десятиле- тиями.
Молекула РНК вируса табачной мозайки заключена в белковый капсид, состоящий из2130
идентичных полипептидных субъединиц.
Современная классификация вирусов осно- вана на виде и формы их нуклеиновойкислоты.
Do you know what retrovirus is? Can you de-scribe the mechanism of its activity? Why can this vi- rus be very dangerous for our cells? What are the typical diseases caused by retrovirus? Make a poster / scheme and explain to the class how retrovirusworks.
Translate the text aboutretrovirus.