New research provides clues to developing better intranasal vaccines for COVID-19 and flu

Date:
August 17, 2021
Source:
American Society for Microbiology
Summary:
While gut microbiota play a critical role in the induction of
adaptive immune responses to influenza virus infection, the role of
nasal bacteria in the induction of virus-specific adaptive immunity
is less clear. New research explores the role of nasal bacteria
and provides clues to developing better intranasal vaccines for
flu and COVID-19.



FULL STORY ========================================================================== While gut microbiota play a critical role in the induction of adaptive
immune responses to influenza virus infection, the role of nasal
bacteria in the induction of virus-specific adaptive immunity is less
clear. New research published this week in mBio,an open-access journal
of the American Society for Microbiology, explores the role of nasal
bacteria and provides clues to developing better intranasal vaccines
for flu and COVID-19.


==========================================================================
"Our study shows that both integrity and amounts of nasal bacteria may
be critical for effective intranasal vaccine," said study principal investigator Takeshi Ichinohe, Ph.D., an associate professor in the
Division of Viral Infection, Department of Infectious Disease Control, International Research Center for Infectious Diseases, Institute of
Medical Science, the University of Tokyo, Minato-ku, Tokyo, Japan. "We
showed that oral bacteria-combined intranasal vaccine protects from
influenza virus and SARS-CoV-2 infection." In the new study, to determine
the effects of nasal bacteria in the induction of mucosal immune responses
to influenza virus infection, Dr. Ichniohe and colleagues treated mice intranasally with an antibiotic cocktail to kill the nasal bacteria
before influenza virus infection.

The researchers found that disruption of nasal bacteria by antibiotics
before influenza virus infection enhanced the virus-specific antibody responses. "We found that intranasal application of antibiotics (to kill
nasal bacteria) could release bacterial pathogen-associated molecular
patterns (PAMP), which are bacterial components that stimulate innate
immunity that act as mucosal adjuvants for influenza virus-specific
antibodies response," said Dr. Ichniohe.

Innate immunity, which is not specific to a particular pathogen, is the
first line of defense against non-self pathogens such as bacteria and
virus. The main purpose of the innate immune response is to immediately
prevent the spread and movement of foreign pathogens throughout the
body. The innate immune responses play an essential role for inducing
the pathogen-specific adaptive immune responses. Adjuvants are substances
that increase or modulate the immune response to a vaccine and stimulate
the innate immune system.

The researchers also found that while the upper respiratory tract
contained commensal bacteria, relative amounts of culturable commensal
bacteria in nasal mucosal surface were significantly lower than that in
the oral cavity. The researchers tested whether intranasal supplementation
of cultured oral bacteria enhances antibody responses to intranasally administered vaccine and found that oral bacteria combined with intranasal vaccine increased antibody responses to intranasally administered vaccine.

Dr. Ichniohe said the findings provide clues to developing better
intranasal vaccines. "We wish to develop effective intranasal vaccines
for influenza and COVID-19 in the near future," said Dr. Ichniohe.

========================================================================== Story Source: Materials provided by
American_Society_for_Microbiology. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Minami Nagai, Miyu Moriyama, Takeshi Ichinohe. Oral Bacteria
Combined
with an Intranasal Vaccine Protect from Influenza A Virus and
SARS-CoV- 2 Infection. mBio, 2021; DOI: 10.1128/mBio.01598-21 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210817084656.htm

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