Transcript Recent advances in micro/nanotechnologies for global control of

BCH
Presented By
Humaira Hussain
PhD Scholar10-Arid-1763
Contents
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General Concepts
Signs and symptoms
Types
Hepatitis B Virus
HBV : Structure
Properties of HBV
Replication of HBV
Global Patterns of Chronic HBV Infection
Concentration of Hepatitis B Virus in Various Body Fluids
Pathogenesis & Immunity
Possible Outcomes of HBV Infection
Epidemiology
Conventional methods for the treatment of Hepatitis B
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Nanotechnology
Introduction to nanotechnology
Recent advances in nanotechnology for
i. Diagnosis of Hepatitis B
ii.Treatment of Hepatitis B
Biosensors
Electrochemical biosensing strategies
Methodolgy
Electrochemical DNA biosensor
Conclusion
Future perspectives
General Concepts
 Hepatitis = 'inflammation of the liver'.
 six medically important viruses are commonly described as
“hepatitis viruses”:
HAV,HBV,HCV,HDV,HEV,HGV.
Signs and symptoms
 Many people with hepatitis go undiagnosed, because the
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disease is mistaken for the flu or because there are no
symptoms at all.
The most common symptoms of hepatitis are:
Loss of appetite
Fatigue
Mild fever
Muscle or joint aches
Nausea and vomiting
Abdominal pain
Conti…..
 Less common symptoms include:
 Dark urine
 Light-colored stools
 Jaundice (yellowing of the skin and whites of the eyes)
 Generalized itching
 Altered mental state, stupor, or coma
 Internal bleeding
Types
 Hepatitis can be
 Acute (inflammation of the liver that lasts less than six
months)
 Chronic (inflammation of the liver that lasts more than
six months)
Hepatitis B Virus
HBV : Structure
Properties of HBV
 A member of the hepadnavirus group
 Circular partially double-stranded DNA viruses
 Replication involves a reverse transcriptase.
 Endemic in the human population and Hyperendemic
in many parts of the world.
 A number of variants
 It has not yet been possible to propogate the virus in
cell culture
Replication of HBV
Concentration of Hepatitis B Virus
in Various Body Fluids
High
Moderate
blood
serum
wound exudates
semen
vaginal fluid
saliva
Low/Not
Detectable
urine
feces
sweat
tears
breastmilk
High-risk groups for HBV infection
 People from endemic regions
 Babies of mothers with chronic HBV
 Intravenous drug abusers
 People with multiple sex partners
 Hemophiliacs and other patients requiting blood and blood
product treatments
 Health care personnel who have contact with blood
 Residents and staff members of institutions for the
mentally retarded
Pathogenesis & Immunity
 Virus enters hepatocytes via blood
 Immune response (cytotoxic T cell) to viral antigens
expressed on hepatocyte cell surface responsible for
clinical syndrome
 5 % become chronic carriers (HBsAg> 6 months)
 Higher rate of hepatocellular ca in chronic carriers,
especially those who are “e” antigen positive
 Hepatitis B surface antibody likely confers lifelong
immunity (IgG anti-HBs)
 Hepatitis B e Ab indicates low transmissibility
Epidemiology
 Human body is a sole reservoir for HBV. However, the high
replication activity of HBV leads to production of high
concentration of viral particles circulating in blood and body
fluids of infected person, and therefore makes hepatitis B
extremely transmissible.
 Most people become chronically infected at childbirth when the
mother is a hepatitis B carrier (vertical transmission), while
others become infected by close personal contact or by
injections (medical and dental instruments or intravenous drug
use) (horizontal transmission).
 The horizontal transmission risk of chronic of HBV infection
incidence is 30% to 50% for the age group between birth and 5
years of age, decreases dramatically to 7–10% by aging
Possible Outcomes of HBV Infection
Acute hepatitis B infection
3-5% of adult-acquired
infections
95% of infantacquired infections
Chronic HBV infection
Chronic hepatitis
12-25% in 5 years
6-15% in 5 years
Cirrhosis
Hepatocellular
carcinoma
Death
20-23% in 5 years
Liver failure
Liver transplant
Death
Global Patterns of Chronic HBV Infection
 High (>8%): 45% of global population
lifetime risk of infection >60%
Early childhood infections common
 Intermediate (2%-7%): 43% of global population
lifetime risk of infection 20%-60%
Infections occur in all age groups
 Low (<2%): 12% of global population
lifetime risk of infection <20%
Most infections occur in adult risk groups
Current Treatment Options
 Interferon alfa (Intron A)
 Response rate is 30 to 40%.
 Lamivudine (Epivir HBV)
(relapse ,drug resistance)
 Adefovir dipivoxil (Hepsera)
Other Methods
 Vaccination
Highly effective recombinant vaccines
 Hepatitis B Immunoglobulin (HBIG)
Exposed within 48 hours of the incident/ neonates whose
mothers are HBsAg and HBeAg positive.
 Other measures
Screening of blood donors, blood and body fluid precautions.
 The control of hepatitis B virus (HBV) infection is a
challenging task, specifically in developing countries where
there is limited access to diagnostics and antiviral treatment
mainly due to high costs and insufficient healthcare
infrastructure.
 Advances in micro/nanotechnology are pioneering the
development of new generation methodologies in diagnosis and
screening of HBV.
 Owing to combination of nanomaterials (metal/inorganic
nanoparticles, carbon nanotubes, etc.) with microfabrication
technologies, utilization of miniaturized sensors detecting HBV
and other viruses from ultra-low volume of blood, serum and
plasma is realized.
What is Nanotechnology?
 The science of manipulating materials on an atomic or
molecular scale especially to build microscopic devices.
Recent advances in nanotechnological tools for
diagnosis of HBV and HBV co-infections
 Advances in nanotechnology and microfluidic platforms
rapidly enable significant developments of biosensing
technologies and medical diagnostics.
 Advances in micro-nanofabrication technologies allow for
developing rapid, user-friendly, accurate and specific
diagnostic methods, which achieve low detection limits of
the target analytes/cells.
Biosensors:
 A biosensor is an analytical device used for the detection
of an analyte that combines a biological component with a
physicochemical detector
 It consists of three parts:
i. The sensitive biological element
ii.The transducer or the detector element
iii. Biosensor reader device
Electrochemical biosensing strategies
 Electrochemical-based sensing technologies have been
one of the most studied platforms in the detection of HBV
biomarkers such as nucleic acids, capsid proteins or other
components.
 In this detection platform, specific recognition elements
are immobilized on a sensor surface or freely present in
the sensing solution, conductivity/resistivity are monitored
upon the recognition and capture of target molecules.
 A recent study demonstrated that simultaneous detection
of 5-type HBV antigens (i.e., hepatitis A, B, C, D, E) is
facilitated by an electrochemical immunosensor array.
Methodolgy
 The described assay is based on following simple
methodology; 5-type HBV antibodies were immobilized
onto a self-made electrochemical sensor array using gold
nanoparticles and protein A as matrices, and the
immunosensor array is then used to capture their
corresponding antigens from sample solution . It is shown
that described electrochemical assay has produced similar
results with respect to ELISA method.
Electrochemical DNA biosensors
 Electrochemical DNA biosensors hold a great promise to
develop biosensors for HBV diagnosis. These biosensors have
demonstrated a broad range of application by utilizing DNA
hybridization,
 Mismatch analysis,
 Direct DNA analysis-based on guanine signal, and
 PCR-based approaches
 In the perspective of DNA hybridization approaches, sensor
surface is chemically modified with single stranded DNA
molecules, which are complementary to HBV specific DNA
sequences.
Conti….
 In one of the latest study, electrochemically deposited Au
nanoparticles on single walled carbon nanotube (SWCNT)
arrays were utilized, to self-assemble of single-stranded
probe DNA on the SWCNT/Au platform for HBV specific
DNA sequences detection.
Conclusion
 Advances in micro/nanotechnology are pioneering the
development of new generation methodologies in
diagnosis and screening of HBV.
 The potential, capability and promising applications of
nanomaterials together with microfabricated and nanoassembled technologies that serve as a sensory system for
detection of viral infections.
Future perspectives
 Although the current diagnostic technologies can reliably
detect HBV, they are relatively laborious, impractical and
expensive for resource-limited settings.
 To achieve effective viral detection, the sensing system
needs to have high sensitivity and selectivity, signal
amplification and label-free detection capabilities.
 Moreover, the ideal sensor must be cost-effective, userfriendly.
Refrences
 Yildiz, UH., F Inci , S Wang , M Toy , HC Tekin ,
A Javaid , DT Lau and U Demirci . 2014. Plant-derived
epigenetic modulators for cancer treatment and
prevention. Biotechnology Advances, 32:1123-32.