Influenza viruses are prevalent worldwide, and it is estimated that more than 200 000 people in the United States are hospitalized each year for respiratory and heart conditions, illnesses associated with
seasonal influenza virus infections.14 Previous epidemiological studies on associations between influenza infection during pregnancy and ASD reported mixed results.
The mapping, says Kawaoka, identifies clusters of viruses featuring novel mutations which, according to the new study, can effectively predict the molecular characteristics of the next
seasonal influenza virus.
Although we are beginning to understand the processes that underlie the evolutionary dynamics of
seasonal influenza viruses, the timing and nature of emergence of new virus strains remain mostly unpredictable.
Despite decades of surveillance and pharmaceutical and non-pharmaceutical interventions,
seasonal influenza viruses continue to cause epidemics around the world each year.
This virus is spreading from person - to - person worldwide, probably in much the same way that regular
seasonal influenza viruses spread.
Not exact matches
The mechanisms behind
seasonal influenza outbreaks are unclear, but understanding these patterns could help health officials wrangle with a notoriously mercurial medical specter caused by a rapidly mutating
virus.
For example, the study showed that while standard testing identified a
virus as
influenza A, which causes
seasonal flu, the new test indicated that the
virus was a particularly harsh subtype called H3N2.
Standard testing failed to detect common, everyday
viruses:
influenza B, a cause of
seasonal flu; parechovirus, a mild gastrointestinal and respiratory
virus; herpes
virus 1, responsible for cold sores in the mouth; and varicella - zoster
virus, which causes chickenpox.
«The
influenza field is largely fixated on studying pandemic or potential pandemic
viruses, but those
viruses only infect a few dozen people every year whereas
seasonal flu infects millions — and yet we don't study human
influenzas closely enough.»
Using
virus histochemical analysis, the investigators looked at the pattern of attachment of two genetically engineered emerging H7
viruses (containing the hemagglutinin (HA) of either
influenza virus A / Shanghai / 1 / 13 or A / Anhui / 1 / 13) to fixed human respiratory tract tissues and compared the findings to attachment patterns seen with human
influenza viruses with high transmissibility but low virulence (
seasonal H3N2 and pandemic H1N1) and highly pathogenic avian
influenza (HPAI)
viruses with low transmissibility and high virulence (H5N1 and H7N7).
Although the world's attention is focused on the novel H1N1
virus causing the swine flu pandemic, H3N2, a
seasonal strain of
influenza, has popped up in many East Asian countries — and some variants in circulation may outfox the
seasonal vaccine in use.
Currently,
seasonal flu vaccines are designed to induce high levels of protective antibodies against hemagglutinin (HA), a protein found on the surface of the
influenza virus that enables the
virus to enter a human cell and initiate infection.
The vaccines targeted an
influenza A H1N1
seasonal flu strain as well as A (H7N9), a
virus considered to have the potential to trigger a human pandemic.
Four
influenza virus lineages co-circulate in the human population to cause
seasonal epidemics.
An analysis of 10 years» worth of data on human
influenza B
viruses has shed new light on the pathogen which can cause the
seasonal flu.
While this year's vaccine is a much better match to the circulating
seasonal strains of
influenza, the shifty nature of the
virus and the need to pick the
viruses used to make global vaccine stocks well before the onset of the flu season can make vaccine strain selection a shot in the dark.
Writing this week (May 23, 2016) in the journal Nature Microbiology, a team of researchers led by University of Wisconsin - Madison School of Veterinary Medicine virologist Yoshihiro Kawaoka describes a novel strategy to predict the antigenic evolution of circulating
influenza viruses and give science the ability to more precisely anticipate
seasonal flu strains.
The never - before - described
virus did not involve the novel H1N1 but instead picked up the surface genes from the
seasonal human H1N1
virus that has long infected humans and combined them with what's known as the triple - reassortant swine
influenza.
In additional experiments, the scientists found that participants who had significant antibody responses did not necessarily also have significant immune system T cell responses to avian
viruses, indicating that these two arms of immunity can be independently boosted after vaccination or infection; that individuals who reported receiving
seasonal influenza vaccination had significantly higher antibodies to the avian H4, H5, H6, and H8 subtypes; and that participants with exposure to poultry had significantly higher antibody responses to the H7 subtype, but to none of the other subtypes tested.
Infectious
virus in exhaled breath of symptomatic
seasonal influenza cases from a college community.
Influenza A virus (IAV) and influenza B virus (IBV) are responsible for seasonal epidemics of respiratory illness amon
Influenza A
virus (IAV) and
influenza B virus (IBV) are responsible for seasonal epidemics of respiratory illness amon
influenza B
virus (IBV) are responsible for
seasonal epidemics of respiratory illness among humans.
In contrast to the yearly epidemics caused by
seasonal influenza, a pandemic can occur when a new
virus emerges in a naive population and is readily transmitted from person to person [59].
Each year, the U.S. Food and Drug Administration, in collaboration with the Centers for Disease Control and Prevention and the World Health Organization, decides which strains of
influenza virus to include in the
seasonal flu vaccine.
Canine H3N2
influenza virus is different than the human H3N2
influenza virus that is a common
seasonal flu
virus in people.
«Unlike human
influenza, this
virus is not
seasonal, so it can be contracted at any time of the year,» Nelson said in a university news release.