What is Pharmacogenomics in Drug
Development?
Table Of Contents
• VIRUS
• DEFINITION
• CLASSIFICATION (BALTIMORE)
GROUP 6 CLASSIFICATION (STRUCTURE, MODE OF REPLICATION)
• RETROVIRUSES
• HIV
• TREATMENT AND PREVENTIONS
• CONCLUSION
• REFERENCES
What is virus?
A virus is a tiny, non-cellular, infectious agent that replicates only inside the
living cells of other organisms. It consists of genetic material (DNA or RNA)
encased in a protein shell (capsid) and can cause diseases in humans, animals,
and plants.
Baltimore Classification
This system categorizes viruses into seven groups based on their
nucleic acid type (DNA or RNA), strandedness (single or double), and
how they produce mRNA.
Group I: Double-stranded DNA (dsDNA)
viruses.
Group II: Single-stranded DNA (ssDNA) viruses.
Group III: Double-stranded RNA (dsRNA) viruses.
Group IV: Positive-sense singlestranded RNA (ssRNA) viruses.
Group V: Negative-sense singlestranded RNA (ssRNA) viruses.
Group VI: ssRNA viruses that use reverse
transcription to replicate.
Group VII: dsDNA viruses that use reverse
transcription to replicate.
Group 6 Classification
i) Retroviruses
ii) HIV
Introduction to Retroviruses
A retrovirus is a virus that uses RNA as its genomic material. Upon
infection with a retrovirus, a cell converts the retroviral RNA into DNA,
which in turn is inserted into the DNA of the host cell. The cell then
produces more retroviruses, which infect other cells.
History
Human Retroviruses:
The first human retrovirus, HTLV-1, was detected and isolated in 1979
by Robert C. Gallo.
Structure Of Retroviruses
Retroviruses are spherical, enveloped particles containing two
identical single-stranded RNA molecules and a protein core, with the
outer lipid envelope consisting of glycoproteins.
Mechanism of Action
When a retrovirus infects a host cell the viral RNA genome is released into the
cytoplasm of host cell.
Then the viral enzyme called reverse transcriptase copies viral RNA to single
stranded DNA.
The viral RNA degrades and reverse transcriptase synthesizes the
complementary second DNA strand.
Then the double stranded DNA enters the DNA of host cell and integrates into
the genome of host DNA using viral enzyme integrase. The integrated DNA is
called provirus.
Then the viral DNA starts making viral RNA which in turn synthesizes proteins.
Diseases caused by retroviruses:(In humans)
Human immuno efficiency viruses e.g AIDS
Human T lymphocyte virus(HTLV-1) associated with adult T-cell leukemia (ATL) and a
neurodegenerative condition called HTLV-1.
Vaccines against Retroviruses
Currently there are no licensed vaccines against retroviruses however the
retroviral vaccines for HIV the research is still ongoing.
Introduction to HIV
HIV, or Human Immunodeficiency Virus, is a virus that attacks the body's immune
system, specifically targeting white blood cells called CD4 cells, leading to a
weakened immune system and increased vulnerability to infections and diseases;
if left untreated, it can progress to AIDS.
History of HIV
Scientists believe that HIV originally came from a virus particular to
chimpanzees in West Africa during the 1930s.
Structure of HIV
HIV-1 virions contain two copies of a single-stranded RNA genome within a
conical capsid surrounded by a plasma membrane of host-cell origin
containing viral envelope proteins.
Mechanism of Action
The seven stages of the HIV life cycle are:
Binding
Fusion
Reverse transcription
integration
Replication
Assembly
Budding.
Disease caused by HIV
Acquired immunodeficiency syndrome (AIDS), is an ongoing, also called
chronic, condition. It is caused by the human immunodeficiency virus,
also called HIV. HIV damages the immune system so that the body is less
able to fight infection and disease.
Vaccines against HIV
There are currently no FDA-approved vaccine to prevent or treat HIV
infection.
Treatment and prevention of retroviruses
including HIV
However there are no approved vaccines for retroviruses also including HIV
but still HIV is being treated with a combination of medicines (pills) taken by
mouth every day
Antiretroviral therapy (ART) is also a treatment of people infected with
human immunodeficiency virus (HIV) using anti-HIV drugs.
In terms of antiretroviral therapies, drugs like azidothymidine (AZT) and other
antiviral agents are utilized for both prophylaxis against the progression of
retroviral infections to disease and for the treatment of established
infections.
Current Research
Current retroviral and HIV research focuses on understanding viral
dynamics, developing new therapies and prevention methods, and
exploring innovative approaches like gene therapy and therapeutic
vaccines, with a focus on overcoming challenges like drug resistance
and persistent viral reservoirs.
Future Directions
Future research directions in retroviral and HIV studies include
understanding viral entry and latency, developing novel therapies and
vaccines, and exploring the role of host factors in viral replication and
pathogenesis.
Conclusion
In conclusion, retroviruses, particularly HIV, pose significant
challenges to human health. Understanding their structure, lifecycle,
and pathogenesis is crucial for developing effective treatments and
prevention strategies. While significant progress has been made in
managing HIV with antiretroviral therapy, ongoing research is essential
to finding a cure and mitigating the impact of retroviral infections. By
continuing to advance our knowledge and collaborate globally, we can
work towards better control and ultimately, the eradication of these
viruses.
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