Taylor Smallwood
Take Home Assignment One
Rabies is a deadly disease caused by a viral infection of the central nervous system. The rabies
virus is most often spread by a bite and saliva from infected (rabid) animal, for example bats, raccoons,
skunks, foxes, ferrets, cats or dogs. In the past, human cases in the United States usually resulted from a
dog bite, but recently more cases of human rabies have been linked to bats and raccoons. Now in the
United States rabies is most commonly associated with bat exposure. There have even been rare cases
in which people have been in caves inhabited by millions of bats and were infected by the rabies virus
through the air. Rabies symptoms include rapidly progressing central nervous system symptoms such as
anxiety, difficulty swallowing and seizures. The rabies virus is very deadly and it replicates very quickly,
so in theory anyone who contracts the rabies virus without the vaccine will die; unless an immediate
healthcare response is received.
The rabies virus is from the lyssavirus. The lyssavirus has helical symmetry. These viruses are
enveloped and have single stranded RNA. The virus encodes five genes whose order is highly
conserved: nucleoprotein (N), phosphoprotein (P), matrix protein (M), and glucoprotein (G), and
the viral polymerase (L). Once within a muscle or nerve cell, the virus undergoes the replication
process. The spikes on the outside of the membrane of the virus interact with a specific cell
receptor on the cell membrane. The cellular membrane pinches and allows entry of the virus
into the cell. The virus then uses the cells environment and binds to its membrane
simultaneously, releasing its five proteins and single stranded RNA into the cytoplasm. When
there are enough proteins the virus will then begin to synthesize new strands of RNA. These
strands will then form complexes with the N,P,L and M proteins and then travel to the inner
membrane of the cell, where a G protein has embedded itself in the membrane. The G protein
then coils around the N-P-L-M proteins taking some of the host cell with it, which will form the
new outer envelope of the virus. The virus then buds off from the cell. From the point of entry,
the virus is unstoppable and moving fast, traveling quickly along neural pathways into the
central nervous system and then to other organs. The salivary glands receive high
concentrations of the virus, ultimately allowing more rapid transmission.
We all have Louis Pasteur to thank for the rabies vaccine. In the 19th century many rabies cases
plagued Europe. In London, for example twenty nine deaths by rabies had occurred in just the
first few weeks of 1877, and the local authorities gave people the right to muzzle, control and
kill stray dogs to try and stop the spread of rabies on the street. Louis Pasteur then began his
work on rabies in 1880. His original plan was to find ways to prevent the disease from
happening at all. He first succeeded in stabilizing the rabies virus by multiple transmissions from
one species to another. He would isolate the suspected microorganisms and take them out of
an infected organism and inject them into a healthy organism and observe any changes in the
healthy organism. Starting in 1884, there were successful results of preventative rabies
vaccinations on dogs. The principle of vaccination before exposure to rabies in animals was
established. Louis Pasteur then had the idea to use this vaccination to create immunity after a
bite, and give it to a human. Pasteur made it happen in 1885 with his first success in humans.
He vaccinated a nine year old boy, Joseph Meister. The young boy suffered multiple deep bites.
He received thirteen injections of the rabies vaccine ( one per day) and survived.
Works Cited
1. College of Physicians in Philadelphia. "Louis Pasteur." History of Vaccines RSS. N.p., 2013. Web.
15 Sept. 2013.
2. CDC. "Rabies." Centers for Disease Control and Prevention. Centers for Disease Control and
Prevention, 03 June 2013. Web. 15 Sept. 2013.