About this Research Topic
The virus family Orthomyxoviridae contains seven genera: Influenza A virus, Influenza B virus, Influenza C virus, Influenza D virus, Thogotovirus, Infectious Salmon Anemia (ISA) virus and Quaranjavirus. Orthomyxoviruses possess a multipartite single strand negative-sense RNA genome and infect a wide spectrum of hosts including mammals (e.g. humans, horses, pigs, dogs, cattle, sea-mammals, etc.), birds, fish, ticks, and mosquitoes. However, orthomyxoviruses are different in their structure, host range and transmission. The genome of Influenza A, Influenza B and ISA viruses is composed of 8 gene segments, Influenza C, Influenza D and Quaranjavirus has 7 gene segments and Thogotovirus displays 6 segments only. While Influenza A viruses infect a wide range of mammals and birds, other viruses have a narrow host range. Orthomyxoviruses are usually transmitted horizontally; interestingly ISA virus can be transmitted vertically (mother-to-offspring). Influenza viruses are transmitted mainly by aerosol, whereas Thogotovirus and Quaranjavirus are transmitted by ticks.
RNA viruses have a high mutation rate due to the error-prone nature of the viral RNA dependent RNA polymerase. Gradual accumulation of non-synonymous mutations in virus genome results in antigenic drift and vaccination failure. Infections with Influenza A and B cause severe illness and high fatality rate in humans despite of vaccination. This requires the regular update of vaccines to provide higher protection rates. Similar drift have been recently described in influenza A viruses in poultry and resulted in vaccination failure. Moreover, the multipartite genome of orthomyxoviruses enables swapping of gene segments (reassortment) between some viruses and thus expanding their host range or increase the adaptation to harsh environmental conditions. Pandemic influenza viruses in 1918, 1957 and 2009 caused by reassortant viruses from human, swine and/or bird origins resulting in millions of deaths. Continuous jumping of influenza viruses particularly from birds and pigs to humans poses a serious risk for global health.
Many of orthomyxoviruses cause severe economic losses in animal production due to high mortality or decrease productivity. Up to 100% mortality in birds has been reported in poultry after the infection with highly pathogenic avian influenza viruses (HPAIV). Likewise, severe mortality in salmons has been reported due to infection with virulent ISA viruses. HPAIV and virulent ISA viruses emerge from low pathogenic or avirulent precursors. Molecular mechanisms for the shift to high virulence or interspecies transmission are recently hot topics for research.
The collection of articles will include, but not limited to, the following topics:
Epidemiology of Orthomyxoviruses in different host species
Development of diagnostic tools
Virus-host interaction including virus entry, proteolytic activation, replication and transcription
Interaction and co-infections with other pathogens
Pathogenicity and virulence determinants
Vaccination and immune response
Chemotherapy and alternative antivirals
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