Orthomyxoviridae
• Genus Influenzavirus A
• Genus Influenzavirus B
• Genus Influenzavirus C
• Genus "Thogoto-like Viruses"
• Infects vertebrates.
• Virions contain 7 segments of to 8 segments of linear negative-sense single stranded RNA.
• Genome length - 12000-15000 nt. Longest 2300-2500 nt, second longest 2300-2500 nt, third 2200-2300 nt, fourth 1700-1800 nt, fifth 1500-1600 nt, sixth 1400-1500 nt, seventh 1000-1100 nt, eighth 800-900 nt.
• Has terminal repeated sequences; repeated at both ends. Terminal repeats at the 5'-end 12-13 nucleotides long, at the 3'-end 9-11 nucleotides long. Encapsidated genomic nucleic acid. Virus may contain defective interfering copies of nucleic acid.
• Virus can exist in different forms during cycle
• Envelop can be in spherical (50-120 nm diameter), or filamentous (20 nm diameter and 200-300(-3000) nm length).
• 500 spikes (projecting 10-14 nm from the surface), in which some dispersed evenly over virus (haemagglutininesterase (HEF)) while some are in clusters (haemagglutinin (HA) major glycoprotein is intervened unevenly by clusters of neuraminidase (NA), ratio of HA to NA about 4-5:1).
• Nucleocapsid(s) enclosed within lipoprotein membrane; nucleoproteins of different size classes with loop at each end. Nucleocapsids filamentous; with no clear modal length (of different size classes); 50-130 nm long; 9-15 nm in diameter. Symmetry helical.
Influenza A
Further classified, based on viral surface antigens hemagglutinin (HA or H), 16 subtypes and neuraminidase (NA or N), 9 subtypes.
Strains identified by standard nomenclature specifying virus type, geographical location where first isolated, sequential number of isolation, year of isolation, and HA and NA subtype. E.g. A/Moscow/10/99 (H3N2), B/Hong Kong/330/2001
Type A most infectious and most severe human-infecting virus among three influenza types. Some serotypes confirmed in humans are H1N1 (Spanish Flu), H2N2 (Asian Flu), H3N2 (Hong Kong Flu), and H5N1 (Avian Flu)
Influenza B
Less common than influenza A.
Known to only infect humans and seals
Mutates 2-3 times lower than type A and less genetically assorted (only 1 influenza B serotype). As a result, a degree of immunity to influenza B is usually acquired at an early age.
Pandemics of influenza B do not occur because influenza B does not mutate to extent that lasts immunity, which ensures reduced rate of antigenic change and limited host range.
Influenza C
Infects humans and pigs, and can cause severe illness and local epidemics.
Less common than other types and usually seems to cause less severe diseases in children.
Thogotovirus
Can replicate in both tick and vertebrate cells
Usually transmitted by ticks.
Can spread from infected to uninfected ticks when co-feeding on uninfected guinea-pigs, even though guinea-pigs are asymptomatic to virus.
THOV (6 RNA segments) isolated from ticks in Africa and southern Europe and known to infect humans in natural settings.
DHOV (7 RNA segments) isolated from ticks in India, eastern Russia, Egypt, and southern Portugal and is able to infect humans, causing a febrile illness and encephalitis.
• Genus Influenzavirus A
• Genus Influenzavirus B
• Genus Influenzavirus C
• Genus "Thogoto-like Viruses"
• Infects vertebrates.
• Virions contain 7 segments of to 8 segments of linear negative-sense single stranded RNA.
• Genome length - 12000-15000 nt. Longest 2300-2500 nt, second longest 2300-2500 nt, third 2200-2300 nt, fourth 1700-1800 nt, fifth 1500-1600 nt, sixth 1400-1500 nt, seventh 1000-1100 nt, eighth 800-900 nt.
• Has terminal repeated sequences; repeated at both ends. Terminal repeats at the 5'-end 12-13 nucleotides long, at the 3'-end 9-11 nucleotides long. Encapsidated genomic nucleic acid. Virus may contain defective interfering copies of nucleic acid.
• Virus can exist in different forms during cycle
• Envelop can be in spherical (50-120 nm diameter), or filamentous (20 nm diameter and 200-300(-3000) nm length).
• 500 spikes (projecting 10-14 nm from the surface), in which some dispersed evenly over virus (haemagglutininesterase (HEF)) while some are in clusters (haemagglutinin (HA) major glycoprotein is intervened unevenly by clusters of neuraminidase (NA), ratio of HA to NA about 4-5:1).
• Nucleocapsid(s) enclosed within lipoprotein membrane; nucleoproteins of different size classes with loop at each end. Nucleocapsids filamentous; with no clear modal length (of different size classes); 50-130 nm long; 9-15 nm in diameter. Symmetry helical.
Influenza A
Further classified, based on viral surface antigens hemagglutinin (HA or H), 16 subtypes and neuraminidase (NA or N), 9 subtypes.
Strains identified by standard nomenclature specifying virus type, geographical location where first isolated, sequential number of isolation, year of isolation, and HA and NA subtype. E.g. A/Moscow/10/99 (H3N2), B/Hong Kong/330/2001
Type A most infectious and most severe human-infecting virus among three influenza types. Some serotypes confirmed in humans are H1N1 (Spanish Flu), H2N2 (Asian Flu), H3N2 (Hong Kong Flu), and H5N1 (Avian Flu)
Influenza B
Less common than influenza A.
Known to only infect humans and seals
Mutates 2-3 times lower than type A and less genetically assorted (only 1 influenza B serotype). As a result, a degree of immunity to influenza B is usually acquired at an early age.
Pandemics of influenza B do not occur because influenza B does not mutate to extent that lasts immunity, which ensures reduced rate of antigenic change and limited host range.
Influenza C
Infects humans and pigs, and can cause severe illness and local epidemics.
Less common than other types and usually seems to cause less severe diseases in children.
Thogotovirus
Can replicate in both tick and vertebrate cells
Usually transmitted by ticks.
Can spread from infected to uninfected ticks when co-feeding on uninfected guinea-pigs, even though guinea-pigs are asymptomatic to virus.
THOV (6 RNA segments) isolated from ticks in Africa and southern Europe and known to infect humans in natural settings.
DHOV (7 RNA segments) isolated from ticks in India, eastern Russia, Egypt, and southern Portugal and is able to infect humans, causing a febrile illness and encephalitis.
Acknowledgements
http://en.wikipedia.org/wiki/Orthomyxoviridae
http://en.wikipedia.org/wiki/Thogotovirus
http://www.virology.net/Big_Virology/BVRNAortho.html
http://en.wikipedia.org/wiki/Orthomyxoviridae
http://en.wikipedia.org/wiki/Thogotovirus
http://www.virology.net/Big_Virology/BVRNAortho.html
No comments:
Post a Comment