Delayed immune responses may drive COVID-19 mortality rates among men
and the elderly
Immune responses to SARS-CoV-2 may depend on viral load and infection
time course

Date:
September 8, 2020
Source:
PLOS
Summary:
COVID-19 (SARS-CoV-2) infections tend to be more severe among older
adults and males, yet the mechanisms underlying increased mortality
in these two demographics are unknown. A new study suggests that
varying immune responses to SARS-CoV-2 due to age and sex may
depend on viral load and the time-course of infection.



FULL STORY ========================================================================== COVID-19 (SARS-CoV-2) infections tend to be more severe among older
adults and males, yet the mechanisms underlying increased mortality
in these two demographics are unknown. A study published in the open
access journal PLOS Biology on September 8, 2020 by Nicole Lieberman and Alexander Greninger at University of Washington and colleagues suggests
that varying immune responses to SARS-CoV-2 due to age and sex may depend
on viral load and the time-course of infection

==========================================================================
The clinical manifestations of COVID-19 vary widely across different
patient populations, despite the virus's limited genetic diversity. To
better understand the mechanisms that drive the diverse responses of
infected individuals (hosts) among different patient demographics,
researchers extracted and sequenced viral RNA from swabs collected from
430 COVID-19 positive cases and 54 negative controls. The scientists
then analyzed the hosts' antiviral and immune responses across infection status, viral load, age and sex.

Researchers found that immune cell responses were not activated
until after three days following the onset of infection, and that
immune cell composition and function fluctuated with viral loads,
in a way that suggested a dysfunctional antiviral response in males
and the elderly. While these findings have important implications for development of immunomodulatory treatments for SARS-CoV-2, additional
studies are needed as swabs were taken from the nasopharynx, which is
not a sensitive anatomic location for accurately examining markers of
systemic inflammation.

Elderly individuals as well as men have suffered higher mortality rates
since the onset of the SARS-CoV-2 pandemic and may indicate weaker immune responses underlying poor clinical outcomes. According to the authors, "Collectively, our data demonstrate that host responses to SARS-CoV-2
are dependent on viral load and infection time with observed differences
due to age and sex that may contribute to disease severity."

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


========================================================================== Journal Reference:
1. Nicole A. P. Lieberman, Vikas Peddu, Hong Xie, Lasata Shrestha,
Meei-Li
Huang, Megan C. Mears, Maria N. Cajimat, Dennis A. Bente, Pei-Yong
Shi, Francesca Bovier, Pavitra Roychoudhury, Keith R. Jerome,
Anne Moscona, Matteo Porotto, Alexander L. Greninger. In vivo
antiviral host transcriptional response to SARS-CoV-2 by viral
load, sex, and age. PLOS Biology, 2020; 18 (9): e3000849 DOI:
10.1371/journal.pbio.3000849 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200908142937.htm

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