ORTHOMYXOVIRUS(PRS).pptx

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. VIRUS CLASSIFICATION Orthomyxoviritae FAMILY :

3. Orthomyxoviridae  is a family of  negative-sense   RNA viruses . It includes seven  genera :  Alphainfluenzavirus   Betainfluenzavirus   Deltainfluenzavirus   Gammainfluenzavirus   Isavirus   Thogotovirus Quaranjavirus .

4. 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 ).

5. Orthomyxovirus Genera, Species, and serotypes Genus Species  (* indicates  type species ) Serotypes  or Subtypes Hosts Alphainfluenzavirus Influenza A virus * H1N1 ,  H1N2 ,  H2N2 ,  H3N1 ,  H3N2 ,  H3N8 ,  H5N1 ,  H5N2 ,  H5N3 ,  H5N8 ,  H5N9 ,  H7N1 ,  H7N2 ,  H7N3 ,  H7N4 ,  H7N7 ,  H7N9 ,  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  (including human) Dhori virus Batken virus ,  Bourbon virus ,  Jos virus Quaranjavirus Quaranfil virus ,*  Johnston Atoll virus

6. 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.

7. 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

8. GENOME

9. 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.

10. TYPES

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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