Maintenance of
neutralizing SARS-CoV-2 antibodies over five months in convalescent
SARS-CoV-2 afflicted patients.
Short title: Serologic study on the longevity of humoral immunity
against SARS-CoV-2.
Sissy Therese Sonnleitner1,3, Martina
Prelog4, Bianca Jansen1, Chantal
Rodgarkia-Dara5, Sarah Gietl1,
Carmen Maria Schönegger1, Stephan
Koblmüller2, Christian Sturmbauer2,
Wilfried Posch3, Giovanni Almanzar4,
Hanna Jury4, Norbert Nowotny6,7,
Gernot Walder1.
1 Dr. Gernot Walder GmbH, Medical Laboratory,
Department of Virology, 9931 Ausservillgraten 30, Austria.
sissy.lamprecht@infektiologie.tirol
2 Institute of Biology, University of Graz,
Universitaetsplatz 2, 8010 Graz, Austria.
3 Division of Hygiene and Medical Microbiology,
Medical University of Innsbruck, 6020 Innsbruck, Austria.
4 University Hospital Wuerzburg, Department of
Pediatrics, University of Wuerzburg, Josef-Schneider-Str. 2, Wuerzburg,
Germany.
5 THP Medical products, Shuttleworthstrasse 19, 1210
Vienna, Austria.
6 Viral Zoonoses, Emerging and Vector-Borne Infections
Group, Institute of Virology, University of Veterinary Medicine Vienna,
Veterinaerplatz 1, 1210 Vienna, Austria.
7 Department of Basic Medical Sciences, College of
Medicine, Mohammed Bin Rashid University of Medicine and Health
Sciences, Building 14, Dubai Healthcare City, Dubai, United Arab
Emirates.
ABSTRACT
Level and duration of protective immunity against SARS-CoV-2 after
primary infection is of crucial importance for preventive approaches. In
order to provide evidence for the longevity of specific antibodies, we
investigated the generation and maintenance of neutralizing antibodies
of convalescent SARS-CoV-2-afflicted patients over a five month period
post primary infection using an immunofluorescence assay, a commercial
chemiluminescent immunoassay and an in-house enzyme-linked
plaque-reduction neutralization assay.
We present the successful application of an improved version of the
plaque-reduction neutralization assay, which can be analyzed
optometrically, significantly simplifying the interpretation of the
results. Based on the results of the plaque-reduction neutralization
assay, neutralizing antibodies were maintained in 85.3% of convalescent
individuals without significant decay over five months. Furthermore, a
positive correlation between severity of infection and neutralizing
titer was shown.
In conclusion, SARS-CoV-2-afflicted individuals have been proven to be
able to establish and maintain neutralizing antibodies over a five
months’ period after primary infection which allows to hope for
long-lasting presumably protective humoral immunity after wild-type
infection or even after vaccination.
Keywords: SARS-CoV-2, immunity, longevity, neutralization test, IgG
antibodies
INTRODUCTION
Little is known about persistence of the immunologic footprint left in a
convalescent SARS-CoV-2 afflicted patient and first publications showed
discrepancies concerning the longevity of specific IgG antibodies . The
development of specific antibodies in the acute phase of COVID-19 is
well documented and most patients display specific antibody responses
between day 10 and day 21 post infection (Kellam & Barclay, 2020; Long
et al., 2020). Whereas milder courses of disease may result in a delayed
generation of antibodies, in a small number of cases, patients may even
stay antibody-negative after infection with SARS-CoV-2 . In comparable
studies, seropositivity rate reached up to 90% and 100% Studies
investigating the persistence of the antibody response are rare, but it
is known that antibodies to other coronaviruses wane over time, in the
range of 12 – 52 weeks from the onset of symptoms onwards (. Short
follow-up studies showed preservation of SARS-CoV-2 IgG antibody levels
over the course of seven weeks (Xiao et al., 2020), at least in 80% of
patients (Jianyun et al., 2020). In comparison, 90% and 50% of
SARS-CoV-1 infected patients have been shown to maintain IgG antibodies
for two and three years, respectively (.
Short-term immunity is defined as the wane of specific antibodies after
a period of about 40 weeks, which leads to annual or otherwise periodic
outbreaks as is well-known from nonSARS-like human coronaviruses
(nonSARS-like hCoVs) as well as influenza viruses . The knowledge of
duration of protective immunity against SARS-CoV-2 after primary
infection is of great importance for the understanding of possible
future scenarios of herd protection after wild-type infection or
vaccination.
In this study, we accompanied 34 volunteers representing the first
SARS-CoV-2 afflicted patients in East Tyrol and investigated the course
of specific antibody responses beginning in convalescence 21-43 days
after the onset of symptoms until 5 months (22 weeks) later.
In order to analyze potentially protective neutralizing IgG antibodies
against SARS-CoV-2, we developed and introduced a fast and reliable
novel enzyme-linked neutralization assay (ELNA) that allows the
determination of neutralization antibodies within 30 hours.
MATERIAL & METHODS