Research Group Heussler (Malaria I) - Bernhard-Nocht-Institut für ...

Medical Microbiology Section
Identification of the causative agent of SARS
Zusammenfassung
SARS (schweres akutes Atemwegssyndrom) verursachte
in der ersten Hälfte des Jahres 2003 eine
weltweite Epidemie. In Zusammenarbeit mit anderen
Europäischen Institutionen gelang der Abteilung für
Virologie die Identifizierung des Erregers als ein
neues Coronavirus. Auch die ersten RT-PCR Tests
für den Erreger wurden von BNI-Wissenschaftlern
entwickelt.
Summary
A severe acute respiratory syndrome (SARS) caused a
global epidemic in the first half of 2003. In collaboration
with other European insitutions, the Department of Virology
identified the causative agent of this novel disease
as a new coronavirus. The first diagnostic RT-PCR
tests for the new agent were developed by BNITM researchers.
Project Description and Results
In November 2002 the first case of a new infectious
lung disease, termed the severe acute respiratory syndrome
(SARS), occurred in Gungdong province of
south China. During the subsequent months the epidemic
spread to all five continents and eventually came to
a halt in July 2003 after strict quarantine measures had
been imposed. It claimed the lifes of about 10% of patients,
with more than 8000 cases in total.
When SARS was imported into Germany in early March
2003, the causative agent was still unknown. SARS-Patients
were treated in the University Hospital of Frankfurt
and in a pulmonary care facility in Hemer/North Rhine
Westphalia. In close collaboration with the Institute of
Virology in Frankfurt and other European institutions
the Bernhard Nocht Institute identified a novel coronavirus
as the causative agent of SARS.
A physician who had treated a SARS patient in Singapore
was quarantined in the University Hospital of
Frankfurt after being disembarked from an intercontinental
flight. After a Vero cell culture inoculated with his
sputum in the University of Frankfurt showed a cytopathic
effect, culture supernatant was transferred to Hamburg
for genetic analysis. With an RT-PCR method
using 15 different degenerated primer pairs random
amplification fragments were obtained from the cell culture
supernatant and sequenced. The sequences showed
no close similarity to any known DNA sequence,
but its translated amino acid code resembled proteins
of various animal coronaviruses.
The patient meanwhile had made a good clinical recovery
and Frankfurt virologists found antibodies in his se-
68
rum that reacted with the infected culture cells. No
such antibodies were found in serum taken from the
same patient in an earlier phase of the disease. Obviously
the cells contained a coronavirus-like agent that
caused an antibody response along with clinical recovery.
Phylogenetic analysis confirmed a distant but
clear relationship of the new agent with known coronaviruses
(Figure 1).
Figure 1
The PCR Laboratory used the sequence information
they had obtained to design several sets of specific polymerase
chain reaction primers and established diagnostic
tests for the new virus. With the help of a biotech
company (Tib-Mobiol, Berlin), RT-PCR primers
were made available to laboratories worldwide. Test
protocols were distributed via ProMed mail, and positive
control material was made available by the Bernhard
Nocht Institute. The Institute Pasteur used these
tests to examine samples from a cohort of SARS patients
shipped to Paris from Vietnam. The test detected
the virus in all patients classified as »probable SARS«,
in a fraction of patients classified as »suspected
SARS«, and in none of the healthy controls (Table 1).
Table 1