Arbovirus is an informal name for any virus that is transmitted by arthropod vectors. The term arbovirus is a portmanteau word that means arthropod-borne virus.

1. ARBOVIRUS
Aishna Srivastava
M.Sc. Plant Pathology
IARI, IIWBR, Karnal

2. Introduction
• Arbovirus is an informal name for
any virus that
is transmitted by arthropod vectors. The
term arbovirus is a portmanteau word that
means arthropod-borne virus.
• These viruses can cause pandemic diseases in
humans, animals, and crops. The Zika virus
and cassava geminivirus are two such
arboviruses.
• These pathogens often alter host
characteristics to directly or indirectly
influence arthropod vector behaviors or host-
herbivore interactions, thus facilitating
disease transmission.

4. Importance of
studying Arbovirus
Top left panel shows a bean leaf infested with
aphids, one of the most important types of plant
arboviral vectors. Left lower panel, setting up
vector traps in an Right panel shows a maize plant
with maize lethal necrosis disease, which is caused
by co-infection by two arboviruses.
• Arboviruses are growing threat to crop-based
agriculture and native plant communities.Spread or
introduced into new areas is by human activity, but
climate change is playing an increasing role by
altering the geographic ranges of viruses arthropod
vectors.
• Increasing ambient temperature and carbon
dioxide levels, may also decrease a plants’ ability to
resist infection by viruses and colonisation by
arthropod vectors.
• The most ‘successful’ invasive arbovirus is the
tospovirus tomato spotted wilt virus that infects not
only tomato but also over 1,000 other plant species,
including many crops. The virus is transmitted by
thrips, especially the western flower thrips.

5. A majority of plant viruses are carried on the cuticle lining of a vector’s
mouthparts or foregut. This initially appeared to be simple mechanical
contamination, but it is now known to be a biologically complex interaction
between specific virus proteins and as yet unidentified vector cuticle-associated
compounds
Transmission

6. Model of the ingestion-salivation mechanism of noncirculative, nonpersistent
transmission.

7. Aphid head and leaf
as the aphid is
feeding on the
plant. The aphid
stylet protrudes
from the proboscis
(A) and penetrates
intracellularly
through the
mesophyll cells (B)
and into the
vascular bundle (C).

8. • Geminivirus and bunyavirus causes
many notorious crops diseases in
developing countries.
• Both the geminivirus and bunyavirus
are capable of manipulating the host
plant to attract their
corresponding vector insects by
inhibiting host-derived olfactory cues,
in turn
promoting pathogen transmission
among host plants.
Salient Features of Arbovirus Transmission

9. • The scientists found that geminivirus infection
hijacks the function of plant WRKY20 to
dramatically reduce the accumulation of
specialized metabolites, such as insecticidal
glucosinolates, in the vascular tissues on which the
virus and whitefly feed, leading to an easier life for
the geminivirus and whitefly.
• Meanwhile, geminivirus infection redistributes
plant insecticidal metabolites among different cell
types and causes enhanced glucosinolate levels in
nonvascular leaf tissues, e.g., mesophyll cells.

10. CHEMICAL
In developed countries, arthropod-transmitted virus control relies
on insecticides, but challenges include evolving insecticide
resistance in vectors and unintended harm to beneficial insects.
Restrictions or bans on specific chemicals result from these
issues, impacting disease control strategies and ecological
balance.
Genetic modification of plants, for example, by engineering them to
express RNA molecules that induce destruction of viral nucleic
acids (RNA silencing), provides extremely effective virus
resistance. gene editing has been used successfully to mutate genes
encoding host factors needed by viruses to replicate in plants.
Plant-emitted semiochemicals attract or repel vectors, but virus
infection alters these signals, potentially increasing transmission.
Studying these signals may offer strategies like trapping or
repelling vectors for arbovirus protection in crops.
GENETIC MODIFICATION
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PHYSIOLOGICAL

11. BACULOVIRUS

12. Introduction
• Baculoviridae a family of viruses that infects insects.
Arthropods, lepidoptera, hymenoptera, and diptera serve as
natural hosts. There are currently 84 known species in this
family.
• Genome is composed of double-stranded DNA that codes
for genes needed for virus establishment and reproduction.
• The majority of baculoviruses used as biological control
agents are in the genus Nucleopolyhedrovirus.
• They have been shown to have no negative impacts on
plants, mammals, birds, fish, or even on non-target insects.
This is especially desirable when beneficial insects are
being conserved to aid in an overall IPM program, or when
an ecologically sensitive area is being treated.
A) Baculovirus particles, or
polyhedra;
B) Cross-section of a polyhedron.

13. HISTORY
• The earliest records of baculovirus can be
found in the literature from as early as the
sixteenth century in reports of "wilting
disease" infecting silk-producing larva.
• Paillot (1926) described the first granulosis
disease from the larvae of Pieris brassicae.
• Bergold (1947) provided definitive evidence
of the viral nature of disease.
• In 1970 Elcar was the first baculovirus to be
developed for commercial use.
• Since the 1990s Baculoviruses have been
utilized for producing complex eukaryotic
proteins in insect cell cultures.

14. • Usually extremely small, and are composed
primarily of double-stranded DNA that codes
for genes needed for virus establishment and
reproduction.
• Rod shaped
• Very stable and may remain dormant in the
environment for long period before infecting
insects
• Baculoviruses can be found wherever insects
exist.
• Because rain and wind readily carry
baculoviruses from place to place, it is likely
that every piece of land and
• body of water contains some virus particles.
Salient Features
• Baculovirus belong to the
family Baculoviridae.
• Word Baculo has been
derived from the Latin
"baculus" meaning "rod or
stick shaped".
• Baculoviruses are lytic
primarily pathogenic for
insects and non pathogenic to
vertebrates and plants.

15. CLASSIFICATION

16. • A baculovirus particle consists of a
cylindrical nucleocapsid that
surrounds the viral double stranded
DNA.
• They are often embedded in a
crystalline protein matrix called
occlusion body/polyhedron made of
the protein polyhedrin
• Because the genetic material is
easily destroyed by exposure to
sunlight or by conditions in the
host's gut, an infective baculovirus
is protected by polyhedron
Structure

17. • Baculovirus nucleocapsids are rod-shaped and
surrounded by an envelope, and they contain circular
genomes of double-stranded DNA that range in size
from about 80-180 kbp in length.
• It is associated with a highly basic (arginine-rich)
protein of 6.5KDa.
• Baculoviruses are the only known nuclear-replicating
DNA viruses that encode a DNA-directed RNA
polymerase.
They produce two distinct types of enveloped virions: occlusion-
derived virions (ODV), which are embedded in large (5-10
micron) protein crystals called occlusion bodies and are
responsible for horizontal transmission between insects, and
budded virions (BV) are non-occluded which spread infection
from cell to cell.

18. 1. Viruses, like baculoviruses, are obligate
parasites reliant on a host for reproduction.
2. The virion's genetic message takes over
host cells, compelling them to produce more
virus particles.
3. Host insects typically die in a way that
enhances virus transmission.
4. Baculovirus infection begins when an
insect consumes virus particles from a plant.
5. Infected insects die, releasing more virus
on foliage, perpetuating the cycle.
LIFECYCLE

20. 1. Baculoviruses used in biological control, mainly
Nucleopolyhedroviruses (NPVs), are species-specific
and have a narrow spectrum for insecticidal
applications.
2. NPVs show no negative impact on plants,
mammals, birds, fish, or non-target insects.
3. Ideal for conserving beneficial insects in
Integrated Pest Management (IPM) or ecologically
sensitive areas.
4. USDA Forest Service uses Gypchek, containing
gypsy moth NPV, to aerially spray forests, effectively
targeting gypsy moths while sparing other animals.
Baculovirus
as biocontrol agents