“We've developed a screening methodology to
basically look back in time in people's [blood] sera and see what viruses they
have experienced. Instead of testing for one individual virus at a time, which
is labor intensive, we can assay all of these at once. It's onestop shopping”
HMMI Researcher
Dr. Stephen Elledge commenting on their developement of VirScan
Imagine being able to determine every single virus a
patient had ever been infected with from a single drop of blood?
Well, it’s now possible thanks to VirScan, a blood assay
developed by researchers at HHMI (Howard Hughes Medical Institute) as reported
in the article “VirScan
reveals your viral infection history in a single drop of blood”, published
June 4, 2015, Medicalxpress.
The research was led by Dr. Stephen Elledge who
works at Brigham and Women's Hospital while moonlighting at the HHMI as a
researcher. Their research, published in the Friday June 5th 2015
issue of the Journal Nature, outlines
a US$25 test for some one thousand (1000) permutations of the two hundred and
six (206) species of human viruses.
This will allow the assayist to determine every
virus a patient has ever been infected with, based on the antibodies their
Immune System produces. Unfortunately, VirScan can determine when they’d been
infected with those specific viruses.
It works by screening the blood using a specially designed
test, based on reactions to certain antibodies from two hundred and six (206)
species of viruses. Even years after the initial infection by a virus, your
body will continue to produce that particular antibody to protect against
future viral re-infections.
Their research holds the potential of creating a
database of viral history among particular populations of humans, which is
helpful in planning Public Health strategies for Governments. It also can
assist in the treatment of patients as knowledge of their previous viral
infection history could advise doctors what drugs might cause adverse effects
on the patient.
It can also be used a test for vaccines and with an
adjustment in terms o the antibodies it can detect it can also be used to test
for certain autoimmune diseases, bacterial infections and Cancers.
So how exactly does this US$25 test work?
Surprisingly, with the help of my favorite virus; bacteriophages!
Bacteriophages
used in VirScan - How Viral peptide are bait for catching Antibodies
The researchers led by Dr. Stephen Elledge
basically used bacteriophages to mimic those 206 species of viruses.
They did this by taking those know viruses and
denaturing them to produced 93,000 codons from the DNA that are used to produce
viral proteins. DNA molecules are structured in organized combinations of
nucleotide bases called Adenine (A), Guanine (G), Cytosine (C) or Thiamine (T)
in the usual helix shaped ladder-like structure.
Because of the shape of each nucleotide base,
Adenine (A) can only bond with Thiamine (T) and Guanine (G) can only bond with
Cytosine (C). Groups of three (3) of these nucleotide bases representing a
single amino acid is called a Codon.
When several Codon are combined and decoded by mRNA
within a cell's reproductive engine, the amino acids they represent and
combined to represent a fragment of a viral protein molecule called a peptide.
The researchers created a nutrient solution filed
with these Viral DNA fragments. Then they introduced some bacteria to feast
upon the bacterial DNA fragments. The Researchers then allowed these bacteria
to be infected by a certain species of bacteriophage.
Bacteriophages are special viruses that attack
bacteria and are important to protecting the human digestive system against
harmful bacteria as noted in my blog article entitled “Dr
Bas Dutilh’s crAss discovers crAssphage Virus - How Bacteriophages can prevent
Colorectal Cancer and attack other Bacteria”.
These Bacteriophages, in feasting on the bacteria,
also absorbed the DNA fragments from their infected host. Their internal
reproductive mechanisms used to DNA fragments and manufacture the viral
peptide, which manifested on the outer protein coat of the bacteriophage virus.
Bacteriophages can display a many as one thousand
(1000) peptides for one thousand (1000) permutations of the two hundred and six
(206) species of human viruses, making them a super efficient way to test for
multiple viruses all at once from a single drop of blood.
Knowing this, researchers then proceeded to mix the
bacteriophages that had with blood samples from some five hundred and sixty
nine (569) people in the United States, South Africa, Thailand and Peru. The
human Immune systems produce anti-bodies that latch on to the epitopes that are
embedded in the viral peptide.
Then using a chemical binding agent, they then
retrieved the antibodies and some of the bacteriophages attached to them. After
a more thorough washing, they basically had just the antibodies and the viral
protein fragments.
Using Genome sequencing techniques, they were able
to figure out which antibody encoded to which viral peptide and in turn
determine the virus that infected the patient being tested. Good to note that
this antibody that was present in the patient's blood may also be there as a
response to a past vaccination, such as from a MMR (Mumps Measles and Rubella)
vaccination.
Viral
History from 1 drop of Blood - Viral History can also include Autoimmune,
Bacterial and Cancer infections
Some interesting results also turned up from this
VirScan test which involved some 100 million potential antibody/epitope
interactions to quote Dr. Stephen Elledge: “In this paper alone we identified
more antibody/peptide interactions to viral proteins than had been identified
in the previous history of all viral exploration”.
Analysis of the past viral history of the five
hundred and sixty nine (569) people in the United States, South Africa,
Thailand and Peru revealed some interesting statistics:
1. 10
different antibodies on average were present in the blood samples
2. Antibodies
were common in Adults but not in children
3. Patients
from South Africa, Thailand and Peru had
more antibodies than those from United States
4. HIV
infected patients had more antibodies for more virus than non-HIV patients
5. Different
patients antibodies recognized the same viral proteins
As a way of testing the effectiveness of their
VirScan method, they tested patients in their sample known to have HIV and
hepatitis C. VirScan was able to detect the presence of these current viral
infections with an accuracy of 95% to 100%, proof of its accuracy, to quote Dr.
Stephen Elledge: “It turns out that it works really well. We were in the
sensitivity range of 95 to 100 percent for those, and the specificity was
good—we didn't falsely identify people who were negative. That gave us
confidence that we could detect other viruses, and when we did see them we
would know they were real”.
Based on the accuracy in identifying patients with
known viral infections as well as similarity between patient antibody/epitope
interactions with viral peptides, the team was able to improve their analysis
methods and thus the sensitive of the VirScan assay.
At the rate at which the antibody/epitope
interaction take place, Dr. Stephen Elledge estimates a two (2) to three (3)
day turnaround to test one hundred (100) blood samples for all one thousand
(1000) permutations of the two hundred and six (206) species of human viruses using
single drops of blood instead of an entire testube sample.
Viral and bacterial vaccines can be improved via the
use of VirScan as an all-in-one testing method. VirScan can also be expanded to
detect bacterial infections by feeding the bacteriophages DNA fragments from
bacteria.
It can also be modified to detect Cancers as well as
autoimmune diseases, as the bacteriophages adopt the DNA that they consume, all
from one drop of blood.
No comments:
Post a Comment