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Clinical and Diagnostic Laboratory Immunology, November 2004, p. 1182-1184, Vol. 11, No. 6
1071-412X/04/$08.00+0 DOI: 10.1128/CDLI.11.6.1182-1184.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
Specific Immunoglobulin G Antibody Detected in Umbilical Blood and Amniotic Fluid from a Pregnant Woman Infected by the Coronavirus Associated with Severe Acute Respiratory Syndrome
Xiugao Jiang,1
Xing Gao,2
Han Zheng,1,3
Meiying Yan,1,3
Weili Liang,1,3
Zhujun Shao,1
Wei Li,1,3
Enmin Zhang,1
Yuan Hu,1
Rong Hai,1
Dongzheng Yu,1
Biao Kan,1,3 and
Jianguo Xu1,3,4*
Priority Laboratory for Molecular Medical Bacteriology, Ministry of Health,3
National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Changping,1
Beijing Center for Disease Control and Prevention, Beijing,2
Center for Functional Genomics Research, TEDA College, Nankai University, Tianjin, Peoples Republic of China4
Received 29 January 2004/
Returned for modification 10 March 2004/
Accepted 1 May 2004

ABSTRACT
Specific immunoglobulin G antibody for severe acute respiratory
syndrome (SARS) coronavirus was detected in maternal blood,
umbilical blood, and amniotic fluid from a pregnant SARS patient.
Potential protection of fetus from infection was suggested.

TEXT
The rapid spread of the coronavirus (CoV) that causes severe
acute respiratory syndrome (SARS) has led to the report of 5,326
probable cases in China alone since 11 June 2003. A female patient
at Beijing had asked for an abortion, following recovery from
infection with this deadly disease. There was no evidence that
indicated that the fetus was also infected. The patient experienced
a fever of 39°C on April 13 while in the seventh month of
her pregnancy. The patient lived with her husband who had visited
his father in the hospital several times after he was diagnosed
with SARS on March 10. Her husband contracted a fever on April
11 and was clinically diagnosed as a probable SARS case soon
afterwards. The pregnant patient had experienced fever since
April 13 and was admitted to Ditan Hospital and diagnosed as
a suspected SARS case on April 24. An abortion was performed
on May 10, and the specimens of maternal blood, umbilical blood,
and amniotic fluid were collected in the surgery with her permission.
A high titer of immunoglobulin G (IgG) antibody against SARS-CoV
was observed in both the maternal and umbilical blood samples.
The antibody titer was evaluated in series dilution by a SARS
IgG detection kit from Huada Biochemical Company (Beijing, China)
and indirect immunofluorescence assay (IFA) against SARS-CoV.
The enzyme-linked immunosorbent assay (ELISA) kit has been licensed
by the State Food and Drug Administration for serological diagnosis
for SARS. The kit is based on a plate coated with purified whole
virus from culture lysate and labeled anti-human IgG antibodies.
It is an indirect ELISA for the detection of SARS-CoV antibodies
in human serum or plasma. The mean time to seroconversion was
suggested to be 20 days. The serum-specific IgG against CoV
was reported to be detected in 70 out of 75 (93%) clinically
diagnosed SARS patients 28 days after the onset of the disease
(
8,
10). The procedure was performed according to the manufacturer's
instructions. Western blotting with purified protein of whole
SARS-CoV showed that specific IgG antibody against nucleocapsid
(N) protein was also present in maternal blood, umbilical blood,
and amniotic fluid (Fig.
1A). The IFA against SARS-CoV was also
positive (Fig.
1B). The kit was provided by Euroimmun (Medizinische
Labordiagnostika AG, Lübeck, Germany) (slides with SARS
virus-infected cells). However, no SARS-CoV genes were detected
in either the maternal blood, umbilical blood, or fluid when
using a SARS virus fluorescence quantitative PCR diagnostic
kit (Da An Gene Co. Ltd. of Zhong Shan University, Guangzhou,
China). The specific primers and the fluorescence-labeled probe
were designed within the Pol1b gene according to the sequence
found at GenBank accession no.
AY278741.1. The product size
is 85 bp. Each run included positive SARS-CoV genomic template
controls (supplied by the manufacturer) to construct a standard
curve and a no-template control for the extraction to detect
any possible contamination that may have occurred during the
processing of samples. Data were analyzed with software provided
by the manufacturer (
9).
Human CoVs have been implicated in respiratory infections in
hospitalized neonates (
3). Some CoVs, such as the mouse hepatitis
virus, cause infections which are mild in adult animals but
often generate severe and sometimes lethal diseases in neonates
(
2). The maternal antibodies supplied via the placenta and colostrum
efficiently protect newborn animals against the fatal consequences
of acute CoV infections during the critical phase of infection.
Gustafsson et al. (
4) have transferred maternally derived antibody
to enterotropic mouse hepatitis virus to pups by both intrauterine
(IgG) and lactogenic (IgA and IgG) routes. They observed that
the immune mice transmitted equal levels of antibody to three
consecutive litters of pups with no evidence of any decline
(
4). It has also been observed that chicks hatched with high
levels of maternal antibody had excellent protection (>95%)
against infectious bronchitis virus challenge at 1 day of age
(
7). Sows naturally infected with transmissible gastroenteritis
virus (TGEV) exhibited a pronounced decrease in IgG antibody
titers to TGEV in the transmission from colostrum to milk. The
sows primed with porcine respiratory CoV and boosted with TGEV
provided the best passive protection after TGEV challenge exposure
of their litter. Not only litter mortality but also morbidity
was reduced (
6). Our observation suggests that the maternal
antibody specific for SARS virus detected in umbilical blood
and amniotic fluid has the potential to protect the fetus from
infection.
No SARS virus RNA was detected in umbilici fluid, fecal specimens, or mouth-washing saline from the pregnant woman when examined by the SARS virus fluorescence quantitative PCR diagnostic kit. These samples were taken hours before the abortion surgery was performed. It indicated that there is no evidence of transmission of SARS virus through the placental barrier, although the vertical transmission has been observed in mouse hepatitis virus (5). Chen et al. (1) have identified a member of the pregnancy-specific glycoprotein subgroup of the carcinoembryonic antigen gene family that serves as a receptor for mouse hepatitis virus, a murine CoV. However, unlike other pregnancy-specific glycoproteins that are expressed in the placenta, it is expressed predominantly in the brain (1). It is unlikely that pregnant women will be more easily infected by the SARS-CoV than nonpregnant women.

ACKNOWLEDGMENTS
This work was supported by a grant (2003AA208407 to J. Xu) from
the Ministry of Science and Technology of the People's Republic
of China.

FOOTNOTES
* Corresponding author. Mailing address: National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, P.O. Box 5, Changping, Beijing 102206, China. Phone: 861 061739579. Fax: 861 061730233. E-mail:
xujg{at}public.bta.net.cn.


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Clinical and Diagnostic Laboratory Immunology, November 2004, p. 1182-1184, Vol. 11, No. 6
1071-412X/04/$08.00+0 DOI: 10.1128/CDLI.11.6.1182-1184.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.