This week I’d like to briefly
discuss viroid’s and the way they can impact the human body. Viroid’s are infectious agents that are composed of a
single piece of circular single-stranded RNA which consist of several double
stranded regions. They are also catalytic RNA that cleave other RNA to
Create fragments containing a 5'-hydroxyl and a 2', 3'-cyclic phosphate (ATSU).
Viroid’s are primarily
responsible for diseases regarding to plants. However, they have recently been
reported to be the cause a human disease, Hepatitis D. As many of you may know,
Hepatitis D is a severe liver disease. It was previously believed to be caused
by a different virus called the delta agent. It is now known that the delta
agent is actually a viroid enclosed in the virus capsid for hepatitis B and
does not cause hepatitis D directly. However, despite not being the main cause
of hepatitis D, it does contribute to the disease.
An individual can only
have hepatitis D if he or she has a simultaneous infection. In order for hepatitis D viroid to infect the cell, the
cell must also be infected with hepatitis B viroid as well. The viroid damages
the liver by cleaving an essential RNA used during signal recognition. There is
a complementary sequence between a hepatitis D viroid RNA and human liver cell 7S RNA. The hepatitis D virus being a
catalytic RNA causes liver cell death by sequestering the 7S RNA and then
cleaving it.
Symptoms of Hep D include
jaundice, joint pain, abdominal pain, vomiting, loss of appetite, dark urine,
and fatigue. The duration of the infection will determine the intensity of
symptoms experienced by the individual who contracted it. Hepatitis D
infections can either be acute or chronic. If an infection lasts for less than
since months than it is considered acute, if it last longer than six months it
is considered chronic. Acute Hep D infections occur suddenly and usually cause
more severe symptoms. Chronic infections develop gradually overtime. Chronic
infections usually lad to detrimental complications such as liver cirrhosis and
liver scarring. Fun fact, the virus might be present within the body months
prior to experiencing any symptoms.
There is no cure or
vaccine for hepatitis D. There are no antiviral medications that cure the
infection. People who have hep D are usually given large doses interferons, a
type of protein that ceases the spread of the virus and leads to remission of
the disease (virology). Even after taking interferons, people with hep D
usually still test positive for the virus. Despite not having a guaranteed
cure, the virus could go away on its own.
Links:
Very interesting blog post this week! It is so cool when we learn more details about previous facts, (especially diseases) and expand our knowledge. Where would science be without someone coming around trying to prove your wrong. Sucks that there is not a cure, but also I had no idea that it could just go away on its own!
ReplyDeleteWow! This was very interesting to read! I actually did not know about Hepatitis D, so this blog was very eye opening. It sucks that even though they discovered that this disease was caused by hep D, a cure has not been found, but then again science is a process. Very good job!
ReplyDeleteI really liked your blog post this week! I never really learned much about viroids in class, so it was nice to learn something new. It was also interesting to learn more about hep D, and science is always moving forward, so hopefully a cure will be found soon.
ReplyDeleteIt always amazes me how there are things like this that exist in our world. So many steps must be taken for this viroid to spread and yet it still gets a chance to spread. I guess it shows how many people exist with varying ways of life.
ReplyDeletePerhaps this is something that occurs because of the ability for these viroids to change their genetic code is higher than ours. This viroid is only one of many I am sure there are more like it.
I also assume anti-virals must be harder to produce because of the varying ways they attack and survive. Unlike bacteria that have certain weaknesses, we can exploit in the body.
fun fact, indeed ;)
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