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Der Pharmacia Lettre, 2012, 4 (2):649-651
(http://scholarsresearchlibrary.com/archive.html)
ISSN 0975-5071
USA CODEN: DPLEB4
649
Scholar Research Library
Antiviral properties of silver nanoparticles synthesized by Aspergillus sps
G. Narasimha*
1
, Habeeb Khadri
2
and Mohammed Alzohairy
2
1
Department of Virology, Sri Venkateswara University, Tirupati, A.P, India
2
Department of Medical Sciences, College of Applied Medical Sciences, Qassim University,
Qassim,
Kingdom of Saudi Arabia
___________________________________________________________________________________
ABSTRACT
An invitro study was conducted to investigate the antiviral properties of silver nanoparticles synthesized from fungal
strain Aspergillus sps isolated from soil. The isolated and characterized silver nanoparticles exhibited as an
excellent antiviral property on Bacteriophage viral strain. The viral inactivation process was increased with
increasing the concentration of silver nanoparticles.
Key words: Aspergillus sps, Silver nanoparticls, E.coli, Bacteriophage, Antiviral activity.
_____________________________________________________________________________________
INTRODUCTION
In present days, resistance to commercially available antimicrobial agents by pathogenic microorganisms has been
increasing at an alarming rate and has become a serious problem. There is need to search for novel antimicrobial and
antiviral agents from natural and inorganic substances. The inorganic agent silver has been employed as most
antimicrobial agent, since ancient times to fight infections pathogens [1]The significant feature of silver is its broad
spectram antimicrobial property which is due to microbial colonization associated with biomaterial related
infections[2] . There are many invitro studies on antibacterial and antifungal properties of silver nanoparticles. But
the reports on antiviral activity of silver nanoparticles was scanty. Hence there is need for much research on antiviral
compounds including inorganic, organic and metallic nanoparticles from chemical and biological systems for
control of viral diseases in plants, animals, and human beings. In this study, an attempt was made on antiviral
properties of silver nanoparticles synthesized from soil fungi Aspergillus sps.
The viruses are obligative intracellular pathogenic agents in both eukaryotes and prokaryotes, the only real link
between viral bacteriophages and actual human pathogens, is their ability to alter the genome of non-virulent
bacteria strains, producing more virulent strains. Previous reports made on antiviral activity of chemical agents
iodine and chlorine dioxide against viral strains bacteriophag and poliovirus and concluded that oxidative damage of
sulfhydryl groups in the protein coat was an important aspect in the killing mechanism of nanoparticles [3].
Elechiguerra, (2005) [4]
reported that, silver nanoparticles with very small sizes are susceptible to Human Immuno
virus, binding of silver nanoparticles of size less than 5nm to gp120 protein of HIV virus prevented the virus from
attaching itself to the host tissue cells. The indications for use of a novel class of anti-HCV agent and exact antiviral
mechanism of metallic nanoparticles may lead to the development of agents with potent activities against viruses
[5].
G. Narasimha et al Der Pharmacia Lettre, 2012, 4 (2):649-651
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650
Scholar Research Library
MATERIALS AND METHODS
Collection of silver nanoparticles
The silver nanoparticles used in this study was synthesized from fungal strain Aspergillus their size and shapes were
reported [6]
Isolation of viral host (E.coli)
The viral host, bacterial strain (E.coli) was isolated from sewage water and the the culture was isolated on EMB
agar medium by streak plate method under sterile conditions. After incubation the agar plates were incubated in
incubator at 37
0
C . After incubation, the bacterial colonies with metallic shine (unique nature of E.coli) were
observed then transferred to nutrient broth and kept for shaking for preparing E.coli suspension. The viral host
E.coli, bacterial strains were cultured in TGYE medium with following chemical ingredients g/L (Tryptone; 10,
Glucose; 10, Yeast extract; 1, NaCl; 8. Typical viral phage preparations contain approximately 1X10
7
-10
11
cfu/ml.
Enrichment of Bacteriophages
The bacteriophages were enriched by standard methods [7].
For this a known volume of sewage water was
transferred to conical flask; 5ml of 10X nutrient broth was transferred. This preparation was kept for mechanical
shaking for 5-6 hrs at room temperature.
Inactivation of virus with nanoparticles
The isolated viral strains in the sewage samples were treated with the silver nanoparticles with various
concentrations (30-240ppm) prepared and treated with virus particles in suspension and the mixture was vortexed
and incubated.
Plaques formation on medium
The bacteriophage viral suspension (treated and without treated nanoparticles) and the E.coli suspension were mixed
in soft agar medium and poured into replicative plates. After medium solidification is over the plates were incubated
at 37
0
C for 24 to 48 hrs in incubator. After incubation, the plates were observed for formation of plaques (Bacterial
cell lysis) and the number of plaques was counted.
RESULTS AND DISCUSSION
The antiviral properties of silver nanoparticles isolated from soil fungi Aspergillus sps on bacteriphage was studied
and the results were reported in table.1. With increasing the nanoparticles concentration from 30-210 ppm the
veridical property also increased. It is an indication of decreasing the plaques number on the medium. Various
nanoparticle concentrations used in this study, the nanoparticles concentrations from 30-180ul range reduced the
plaque number, whereas at 210-240ppm totally inhibited the viral growth in host (bacteria)which is indication of
complete inhibition of viral replication (viral growth) in host.(table.1). Similarly an vitro studies have contributed to
the understanding of possible mechanisms by which nanoparticles or metal oxides such as Arsenic, Antimony leads
to induction of apoptosis, inhibition of growth and angiogenesis, modulation of cellular signaling pathways,
perturbation of cellular redox status, and promotion of differentiation[8].The two primary mechanisms control the
oxidant disinfection efficiency by hydroxyl radicals: [9] oxidation and disruption of the cell wall and membrane
with resulting disintegration of the cell [10].The diffusion of antiviral agent into the cell where it may inactivate
the enzymes, damage intracellular components, interfere with protein synthesis and DNA replication[11]. The lower
surface to volume ratio of the viruses may provide greater rates of hydroxyl radical reaction with intracellular
biological molecules compared with the larger bacterial cells. The relatively slow diffusion of hydroxyl radicals into
viruses, and particularly bacterial cells, may be the cause of its low disinfection rate, and may limit its use as a
disinfectant [12] The antiviral activity in the present study correlates with antimicrobial activity of silver
nanoparticles from Aspergillus niger jaydev and Narasimha ( 2010) [13] and white button mushrooms (Agaricus
bisporus) Narasimha et al ( 2011) [14].
Elechiguerra et al (2005) [4] reported that
the silver nanoparticles with very
small size are susceptible to bacteria and fungi and HIV, binding of silver nanoparticles of size equal /less than 5nm
to gp 120 protein of HIV virus prevented the virus from attaching itself to the host tissue cells. Further research
needs to be in-depth of work on antiviral properties of silver nanoparticles and their molecularchr mechanism on
viral inhibition.
G. Narasimha et al Der Pharmacia Lettre, 2012, 4 (2):649-651
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651
Scholar Research Library
Table.1.Ant viral properties silver nanoparticles at various concentrations
Plate No Silvernanoparticle suspension (in ppm) No. of Plaques*
1 Without silvernanoparticles (Control) 120
2 30 72
3 60 54
4 90 34
5 120 18
6 150 9
7 180 2
8 210 ND
9 240 ND
*Values represented in the table are mean of duplicates
Pfu plaque forming units
ND: Not detected
CONCLUSION
Silver nanoparticles synthesized from soil fungi, Aspergillus sps effectively inhibited the growth of Bacteriophage
virus in host bacteria. The viral inactivation process was increased with increasing the concentration of nanoparticle
is an indication of antiviral properties of silver nanopartilces.
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