Virology

1. -A Presentation by Samvartika Majumdar
8/10th sem
Int MSc Biotechnology

2.  Emerging viral diseases have threatened
humanity throughout history.
 Specific aspects of modernization such as
rapid air transit, as well as demographic
trends including urbanization, have
accelarated both the emergence and spread
of viruses.
 From advanced genomic sequencing to new
methods in structural biology, there are
increasingly sophisticated toolkits with which
to facilitate the detection and possible control
of emerging viral diseases.

3.  Current outbreaks of viral diseases include
chikungynya fever, Ebola virus disease,
influenza viruses, HIV, Hepatitis B and C etc.,
and the most recently trending is the Zika
virus.
 Most emerging viral diseases are from the
RNA viruses.
 Unfortunately, the RNA viruses have higher
mutation rates than do DNA viruses because
viral RNA polymerases lack the proofreading
activity.
 As a result, it is being difficult to make
effective vaccine against these pathogens.

4. Technology Application to emerging viral
infections
Genomic sequencing Identifi cation of new agents (such as
SARS-CoV and MERS-CoV);
evaluation of strain diversity (HIV)
Rapid diagnostics Real-time reverse transcription-PCR
for Ebola virus; distinguishing bacterial
versus viral causes of certain acute
respiratory illness
Structural biology Vaccine design for influenza, HIV,
respiratory syncytial virus; therapeutics
design for HIV, HCV
New vaccine platforms Viral vectors for Ebola virus, Marburg
virus, HIV; virus-like particles for
chikungunya virus; nanoparticle
platforms for influenza virus
immunogens

5. A. Detection of nucleic acids
1. Nucleic acid extraction
2. Polymerase chain reaction (PCR) and real-time PCR
3 Isothermal amplification
4. Detection of nucleic acids without DNA amplification
5. Diagnosis by restriction fragment length
polymorphisms and related DNA-based approaches
6. Genome sequencing
7. Diagnosis by DNA probes and DNA microarray
technology
8. Metagenomics

6. B. Detection of proteins
B1. Detection of antigens
1. Antigen-capture enzyme-linked
immunosorbent assay (AgELISA)
2. Quantitative immunoassays
(radioimmunoassay and quantitative enzyme
immunoassay)
3. Fluorescence antibody test
4. Immunohistochemistry
5 Immunochromatography (lateral flow
devices)

7. B2. Detection of antibody
1. Agglutination
2. Haemaglutination inhibition test
3. Agar gel immunodiffusion test
4. Complement fixation test
5. Indirect ELISA (iELISA)
6. Competitive ELISA (cELISA)
7. Blocking ELISA (bELISA)
8. Immunoblotting
9. Fluorescent

8.  Whereas genomic sequencing has facilitated
identification of viruses, other advances are
helping to diagnose viral illnesses.
 Specifically, polymerase chain reaction (PCR), is
now more rapid and less cumbersome, allowing
for deployment in outbreaks, even in resource-
poor settings.
 PCR technology can be particularly useful in
situations of diagnostic uncertainty, a difficulty
encountered in hemorrhagic fever outbreaks,
such as the ongoing Ebola virus disease outbreak
in West Africa.

9.  Hemorrhagic manifestations, when they occur,
may appear late in the course of disease.
 The nonspecific symptomatology creates
diagnostic uncertainty that complicates disease
control.
 Therefore, rapid accurate diagnostics are
essential. Real-time reverse transcription PCR, a
quantitative RNA-based technology, has been
developed and deployed in outbreaks.
 The ability to diagnose infection within hours has
been invaluable in disease control, facilitating
both case identification and contact tracing.
 Rapid diagnostics also have proved important for
more common pathogens, including respiratory
viruses such as respiratory syncytial virus and
parainfluenza viruses.

10. Basically the chemotherapeutic agents against
viral infections can be categorised into the following
three main categories :
1.Virucides
 These are the agents or drugs that inactivate intact
viruses.
 They cause inactivation of the virus in a single step.
 These affect both the viral cell and the host cell, so
are not used generally.
 However they can be used in preventing the
transmission of viruses.
 The examples include organic solvents, detergents
and ultravoilet light.

11. 2. Antivirals
 These are the agents or drugs that inhibit
viral replication at certain levels.
 These specifically have a restricted spectrum
of activity and cannot be used for latent
viruses.
3. Immunomodulators
 These consist of agents that augment the
host response to infections.
 They help in boosting up the host immune
response by secreting antibodies, interferons
or by intensifying the cell mediated immunity.

12.  Some common antiviral drugs are –
Virus Drug Target Chemical
type
Route
Influenza A,
B
strains
Zanamivir,
Oseltamivir
Viral
neuraminida
se inhibitor
A transition
state
analogue
inhibitor of
neuraminida
se
Inhalation,
Oral
Yellow fever
virus
Mycophenoli
c acid
IMP
dehydrogen
ase inhibitor
-
Oral,
intravenous
HIV Amprenavir,
Lopinavir,
Stavudine
etc
Peptide
analogue
Reverse
transcriptase
HIV
proteases
Thymidine
analogue
Oral
Hepatitis-B
virus
Penciclovir Virus
polymerase
Guanine
analogue
Topical

13.  Many new techniques have been introduced into drug
discovery and development in order to speed up the
process and overcome the high costs.
 These tools include genomics, proteomics,
metabolomics, biomarkers, bioinformatics, and
molecular imaging techniques.
1. Molecular Imaging
The molecular imaging technique can be used for
various different purposes such as anatomical studies
for structural morphology of organs or tissues,
including computerized tomography (CT), magnetic
resonance imaging (MRI), and ultrasound.

14. 2.Role of DNA microarray
 DNA microarray is an important tool that has been
efficiently utilized in the development of host-protein
target.
 The technique has several advantages the major one
being the analysis of a large number of samples.
 DNA microarray has been used to study the host
response to HCMV infection.
3. Biomarkers
 Biomarkers are signature molecules, which can
indicate physiological or biological characteristics
changes in the specific target organs.
 Biomarkers can be used for various purposes like
diagnosis, identifying the organs involved, identifying
the risk of disease, assessing weather the drug
administered is safe and effective in treating the
disease.

15. 4. Animal Testing
 Drugs are administered to the Animals for
measuring the drug level in the blood, its
metabolism, excretion and toxicity of its
metabolites.
5. Bioinformatics
 The use of computational techniques
revolutionized the drug discovery by using the
different computer aided software’s like CADD
(computer aided drug design) CAMM (computer
aided molecular modeling) CADDD (computer
aided drug discovery and development).
 In silico drug design and rational drug designs
minimized the cost and time in screening the
ideal drug candidates

16. 6. QSAR
 Quantitative structure-activity relationship
(QSAR)
 The fundamental principle of QSAR is that
biological properties are functions of
molecular structure.
 QSAR is often used in the drug discovery to
identify the chemical structures which show
inhibitory effects on specific targets.
 Moreover this process is used for quantitative
approach for assessing biological or chemical
activity.

17. 7. Tissue microarray
 Tissue micro array chips are used for testing,
evaluation and efficacy of the drug
distribution and validation.
 These microchips are generally coated with
numerous normal and diseased human
tissues for high throughput screening of the
targets.
 Alternative approaches include – HPLC,
fluorescence based methods, use of antisense
oligonucleotides, aptamers or ribozymes.