Incidence of medically attended influenza and influenza virus infections confirmed by serology in Ningbo City from 2017–2018 to 2019–2020

AbstractWhile vaccines remain the best tool for preventing influenza virus infections, they have demonstrated low to moderate effectiveness in recent years. Seasonal influenza vaccines typically consist of wild-type influenza A and B viruses that are limited in their ability to elicit protective immune responses against co-circulating influenza virus variant strains. Improved influenza virus vaccines need to elicit protective immune responses against multiple influenza virus drift variants within each season. Broadly reactive vaccine candidates potentially provide a solution to this problem, but their efficacy may begin to wane as influenza viruses naturally mutate through processes that mediates drift. Thus, it is necessary to develop a method that commercial vaccine manufacturers can use to update broadly reactive vaccine antigens to better protect against future and currently circulating viral variants. Building upon the COBRA technology, nine next-generation H3N2 influenza hemagglutinin (HA) vaccines were designed using a next generation algorithm and design methodology. These next-generation broadly reactive COBRA H3 HA vaccines were superior to wild-type HA vaccines at eliciting antibodies with high HAI activity against a panel of historical and co-circulating H3N2 influenza viruses isolated over the last 15 years, as well as the ability to neutralize future emerging H3N2 isolates.

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Sequential Seasonal H1N1 Influenza Virus Infections Protect Ferrets against Novel 2009 H1N1 Influenza Virus

Journal of Virology ◽

10.1128/jvi.02257-12 ◽

2012 ◽

Vol 87 (3) ◽

pp. 1400-1410 ◽

Cited By ~ 45

Author(s):

Donald M. Carter ◽

Chalise E. Bloom ◽

Eduardo J. M. Nascimento ◽

Ernesto T. A. Marques ◽

Jodi K. Craigo ◽

...

Keyword(s):

Influenza Virus ◽

H1n1 Influenza ◽

Cross Reactivity ◽

Influenza Viruses ◽

The Novel ◽

Virus Infections ◽

H1n1 Influenza Virus ◽

Virus Shedding ◽

2009 H1n1 ◽

Novel H1n1 Influenza

ABSTRACTIndividuals <60 years of age had the lowest incidence of infection, with ∼25% of these people having preexisting, cross-reactive antibodies to novel 2009 H1N1 influenza. Many people >60 years old also had preexisting antibodies to novel H1N1. These observations are puzzling because the seasonal H1N1 viruses circulating during the last 60 years were not antigenically similar to novel H1N1. We therefore hypothesized that a sequence of exposures to antigenically different seasonal H1N1 viruses can elicit an antibody response that protects against novel 2009 H1N1. Ferrets were preinfected with seasonal H1N1 viruses and assessed for cross-reactive antibodies to novel H1N1. Serum from infected ferrets was assayed for cross-reactivity to both seasonal and novel 2009 H1N1 strains. These results were compared to those of ferrets that were sequentially infected with H1N1 viruses isolated prior to 1957 or more-recently isolated viruses. Following seroconversion, ferrets were challenged with novel H1N1 influenza virus and assessed for viral titers in the nasal wash, morbidity, and mortality. There was no hemagglutination inhibition (HAI) cross-reactivity in ferrets infected with any single seasonal H1N1 influenza viruses, with limited protection to challenge. However, sequential H1N1 influenza infections reduced the incidence of disease and elicited cross-reactive antibodies to novel H1N1 isolates. The amount and duration of virus shedding and the frequency of transmission following novel H1N1 challenge were reduced. Exposure to multiple seasonal H1N1 influenza viruses, and not to any single H1N1 influenza virus, elicits a breadth of antibodies that neutralize novel H1N1 even though the host was never exposed to the novel H1N1 influenza viruses.

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Exacerbation of Influenza Virus Infections in Mice by Intranasal Treatments and Implications for Evaluation of Antiviral Drugs

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01664-12 ◽

2012 ◽

Vol 56 (12) ◽

pp. 6328-6333 ◽

Cited By ~ 15

Author(s):

Donald F. Smee ◽

Mark von Itzstein ◽

Beenu Bhatt ◽

E. Bart Tarbet

Keyword(s):

Influenza Virus ◽

Influenza A ◽

H1n1 Virus ◽

Antiviral Agent ◽

Virus Production ◽

Lung Pathology ◽

Virus Infections ◽

Challenge Dose ◽

Virus Challenge ◽

Time To Death

ABSTRACTCompounds lacking oral activity may be delivered intranasally to treat influenza virus infections in mice. However, intranasal treatments greatly enhance the virulence of such virus infections. This can be partially compensated for by giving reduced virus challenge doses. These can be 100- to 1,000-fold lower than infections without such treatment and still cause equivalent mortality. We found that intranasal liquid treatments facilitate virus production (probably through enhanced virus spread) and that lung pneumonia was delayed by only 2 days relative to a 1,000-fold higher virus challenge dose not accompanied by intranasal treatments. In one study, zanamivir was 90 to 100% effective at 10 mg/kg/day by oral, intraperitoneal, and intramuscular routes against influenza A/California/04/2009 (H1N1) virus in mice. However, the same compound administered intranasally at 20 mg/kg/day for 5 days gave no protection from death although the time to death was significantly delayed. A related compound, Neu5Ac2en (N-acetyl-2,3-dehydro-2-deoxyneuraminic acid), was ineffective at 100 mg/kg/day. Intranasal zanamivir and Neu5Ac2en were 70 to 100% protective against influenza A/NWS/33 (H1N1) virus infections at 0.1 to 10 and 30 to 100 mg/kg/day, respectively. Somewhat more difficult to treat was A/Victoria/3/75 virus that required 10 mg/kg/day of zanamivir to achieve full protection. These results illustrate that treatment of influenza virus infections by the intranasal route requires consideration of both virus challenge dose and virus strain in order to avoid compromising the effectiveness of a potentially useful antiviral agent. In addition, the intranasal treatments were shown to facilitate virus replication and promote lung pathology.

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