The rabies virus is a bullet shaped, nonsegmented, negative
stranded RNA genome that belongs to the order Mononegaviralesiruses and the
Rhabdoviridae family. Rhabdoviruses are approximately 180 nm long and 75 nm
wide. The rabies genome encodes five proteins: nucleoprotein, phosphoprotein,
matrix protein, glycoprotein and polymerase. All rhabdoviruses have two major
structural components: a helical ribonucleoprotein core and a surrounding
envelope. In the ribonucleoprotein, genomic RNA is tightly encased by the
nucleoprotein. Two other viral proteins, the phospoprotein and the L-protein
are associated with the RNP. The glycoprotein forms approximately 400 trimeric
spikes which are tightly arranged on the surface of the virus. The matrix
protein is associated both with the envelope and the RNP and may be the central
protein of rhabdovirus assembly. The arrangement of these proteins and the RNA
genome determine the structure of the rabies virus.
When a human or animal is injected with infected saliva, the
rabies virus replicates at the site of inoculation. Aided by the glycoprotein
protein, the viral envelope attaches and fuses with the host cell membrane. The
plasma membrane folds inside itself with clathrin-coated pits which allow
cytoplasmic absorption via pinocytosis. The virions aggregate with the large
endosomes, and after fusion with their membranes, they initiate the uncoating
and release of the viral RNP into the cytoplasm. Since the rabies virus has a
linear, single stranded RNA genome, messenger RNAs are produced to permit virus
replication using the host cell machinery. Translation of the genome occurs on
the free ribosomes in the cytoplasm, and some posttranslational processing
occurs in the endoplasmic reticulum and golgi apparatus.
Once infected, the rabies virus travels to the brain by
following the peripheral nerves. The incubation period of the disease is
usually a few months in humans, depending on the distance the virus must travel
to reach the central nervous system. Once the rabies virus reaches the central
nervous system and symptoms begin to show, the infection is effectively
untreatable and usually fatal within days.
Early-stage symptoms of rabies are malaise, headache and fever,
progressing to acute pain, violent movements, uncontrolled excitement,
depression, and hydrophobia. Finally, the patient may experience periods of
mania and lethargy, eventually leading to coma. The primary cause of death is
usually respiratory insufficiency. Overall, roughly 97% of human rabies cases
result from dog bites. In the US, animal control and vaccination programs have
effectively eliminated domestic dogs as reservoirs of rabies.
I am so terrified of this virus for all the reasons listed! I have a cousin that is afraid of dogs because of fear of getting the virus, and I do not blame her. This is crazy and so scary. I looked at at the link Mrs. Jeff posted on the notes of the transplanted organs with rabies. That is so unfortunate.I thought that all organs were tested before being transplanted. I believe the doctors should have investigated more into the cause of the patient's death before transplanting the organs. If they'd had done this, they would have known that the organs were possibly infected with the virus and wouldn't have spread the infection to the transplant recipients.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteI agree with Ashley... this is a horrible and terrifying virus. The first time I saw the effects of this disease was in "Old Yeller." I remember I would be scared if I ever saw a hostile dog acting like "Old Yeller." Thankfully, vaccination is required by law for all pet owners. However, as I was reading, I discovered that immunity for the rabies virus vaccine last seven years.... but the law requires in most cases to administer the vaccine every 3 years?? Is this really necessary if the blood antibody tests proved the "3 year" rabies vaccine builds immunity for seven years? While, I'm just as scared as this virus, as the next person, but do we really need to administer this as often as the law requires? Maybe "Old Yeller" and the horrible nature of this virus is causing the U.S. to be overcautious.
ReplyDeleteRabies Virus has also been a concern of mine. My dad was bitten by a dog a good many years back. Fortunately, the dog did not have rabies and my dad was okay, but I was curious as to how it could be treated once you were bit.I found that there is no treatment for rabies once symptoms appear. However, In the United States, post-exposure treatment for rabies consists of a regimen of one dose of rabies immune globulin and five doses of the rabies vaccine over a 28-day period if you seek treatment immediately after coming into contact with the saliva.
ReplyDelete