PG AND RESEARCH DEPARTMENT OF MICROBIOLOGY - SRI PARAMAKALYANI COLLEGE - ALWARKURICHI

1. ORTHOMYXOVIRUS
K.PRAKASH
I M.Sc MICROBIOLOGY
SUBMITTED TO,
DR.C.MARIAPPAN
ASSISTANT PROFESSOR
SPKC-ALWARKURICHI
SRI PARAMAKALYANI COLLEGE
ALWARKURICHI-624712
virology

2. CONTENTS
• Virus classification
• Introduction
• Genera
• Structure
• Genome
• Replication cycle
• Types
• Vaccines and Prophylaxis
• References

3. VIRUS CLASSIFICATION
• Virus
(UNRANKED):
• Riboviria
REALM:
• Orthornavirae
KINGDOM:
• Negarnaviricota
PHYLUM:
• Insthoviricetes
CLASS:
• Articulavirales
ORDER:
• Orthomyxoviritae
FAMILY:
VIRUS CLASSIFICATION

4. • Orthomyxoviridae is a family of negative-sense RNA viruses.
• It includes seven genera:
INTRODUCTION
1. Alphainfluenzavirus
2. Betainfluenzavirus
3. Deltainfluenzavirus
4. Gammainfluenzavirus
5. Isavirus
6. Thogotovirus
7. Quaranjavirus.

5. • Alphainfluenzavirus infects humans, other mammals, and birds, and causes all flu
pandemics
• Betainfluenzavirus infects humans and seals
• Gammainfluenzavirus infects humans, pigs, and dogs
• Deltainfluenzavirus infects pigs and cattle.
• Isaviruses infect salmon.
• The thogotoviruses are arboviruses, infecting vertebrates and invertebrates (such
as ticks and mosquitoes).
• The Quaranjaviruses are also arboviruses, infecting vertebrates (birds) and
invertebrates (arthropods).
GENERA

6. Orthomyxovirus Genera, Species, and serotypes
Genus
Species (* indicates type
species)
Serotypes or Subtypes Hosts
Alphainfluenzavirus Influenza A virus*
H1N1, H1N2, H2N2, H3N1, H3N2, H3
N8, H5N1, H5N2, H5N3, H5N8, H5N9
, H7N1, H7N2, H7N3, H7N4, H7N7, H
7N9, H9N2, H10N7
Human, pig, bird, horse, bat
Betainfluenzavirus Influenza B virus* Victoria, Yamagata Human, seal
Gammainfluenzavirus Influenza C virus* Human, pig, dog
Deltainfluenzavirus Influenza D virus* Pig, cattle
Isavirus Infectious salmon anemia virus* Atlantic salmon
Thogotovirus
Thogotovirus*
Tick, mosquito, mammal (inclu
ding human)
Dhori virus Batken virus, Bourbon virus, Jos virus
Quaranjavirus Quaranfil virus,* Johnston Atoll
virus

7. STRUCTURE

8. • The influenza virus virion is pleomorphic.
• The viral envelope can occur in spherical and filamentous forms.
• The virus's morphology is ellipsoidal with particles 100–120 nm in diameter, or
filamentous with particles 80–100 nm in diameter and up to 20 µm long.
• There are approximately 500 distinct spike-like surface projections in the
envelope.
• The major glycoprotein spike is interposed irregularly by clusters
of neuraminidase spikes, with a ratio about 10 to 1.
• The ribonuclear proteins are filamentous and fall in the range of 50–130 nm long
and 9–15 nm in diameter with helical symmetry.
STRUCTURE

9. • Viruses of the family Orthomyxoviridae contain six to eight segments of
linear negative-sense single stranded RNA.
• They have a total genome length that is 10,000–14,600 nucleotides (nt).
• The influenza A genome, for instance, has eight pieces of segmented negative-
sense RNA (13,500 nucleotides)
• There are two large glycoproteins found on the outside of the viral particles.
1. hemagglutinin
2. neuraminidase
• Hemagglutinin is a lectin that mediates binding and entry to the target cell from the
viral genome.
• Neuraminidase is an enzyme involved in the release of progeny virus from infected
cells, by cleaving sugars that bind the mature viral particles.
GENOME

10. GENOME

11. REPLECATION CYCLE
• The viruses bind to a cell through interactions between
its hemagglutinin glycoprotein
• The hemagglutinin protein fuses the viral envelope, releasing the
viral RNA molecules into the cytoplasm.
• These proteins and viral RNA form a complex that is transported
into the cell nucleus.
• where the RNA polymerase begins transcribing, complementary
positive-sense cRNA.
• The cRNA is either exported into the cytoplasm and translated .
• Newly synthesised viral proteins are either secreted through
the Golgi apparatus on to the cell surface or transported back
into the nucleus to bind viral RNA and form new viral genome
particles
• The vRNA and viral core proteins leave the nucleus and enter this
membrane protrusion
• The new viral protein or genomic particles containing virus has
released from the host cell.
• After the release of new influenza virus, the host cell dies.

12. TYPES

13. • Influenza A viruses are the most virulent human pathogens among the three influenza types and
cause the most severe disease.
• It is thought that all influenza A viruses causing outbreaks or pandemics originate from wild
aquatic birds.
• since the 1900's were caused by Avian influenza, through Reassortment with human influenza
strains.
• The serotypes that have been confirmed in humans.
• H1N1 caused "Spanish flu" in 1918 and "Swine flu" in 2009.
• H2N2 caused "Asian Flu".
• H3N2 caused "Hong Kong Flu".
• H5N1, "avian" or "bird flu".[36]
• H7N7 has unusual zoonotic potential.[37]
• H1N2 infects pigs and humans.[38]
• H9N2, H7N2, H7N3, H10N7.
INFLUENZA-A

14. • Influenza B virus is almost exclusively a human pathogen, and is less common
than influenza A.
• The only other animal known to be susceptible to influenza B infection is the seal.
• This type of influenza mutates at a rate 2–3 times lower than type A.
• As a result of this lack of antigenic diversity.
• Influenza B is usually acquired at an early age.
• Influenza B mutates enough that lasting immunity is not possible.
• Ensures that pandemics of influenza B do not occur
INFLUENZA-B

15. • The influenza C virus infects humans and pigs.
• It can cause severe illness and local epidemics.
• However, influenza C is less common than the other types.
• Influenza C is usually causes mild disease in children.
INFLUENZA-C

16. • This is a genus that was classified in 2016.
• The members of which were first isolated in 2011.
• This genus appears to be most closely related to Influenza C.
• From which it diverged several hundred years ago.
• There are at least two extant strains of this genus.
• The main hosts appear to be cattle, but the virus has been known to infect pigs as
well.
INFLUENZA-D

17. • Vaccines and drugs are available for the prophylaxis and treatment of influenza
virus infections.
• Vaccines are composed of either inactivated or live attenuated virions of the
H1N1 and H3N2 human influenza A viruses, as well as those of influenza B
viruses.
• Because the antigenicities of the wild viruses evolve, vaccines are reformulated
annually by updating the seed strains
• When the antigenicities of the seed strains and wild viruses do not match,
vaccines fail to protect the vaccineed In addition, even when they do match,
escape mutants are often generated.
• Drugs available for the treatment of influenza include Amantadine, Rimantadine,
Oseltamivir , Zanamivir, and Peramivir.
• However, escape mutants are often generated for the former drug and less
frequently for the latter drug
VACCINES AND PROPHYLAXIS

18. • https://en.wikipedia.org/wiki/Orthomyxoviridae
• https://www.osmosis.org/notes/Orthomyxoviruses
• https://www.slideshare.net/nomank992/orthomyxoviruses
• https://www.slideshare.net/RagyaBharadwaj/orthomyxovirus-morphology-and-
laboratory-diagnosis
REFERENCES