Dan McLeod's response to my request that he comment on his 1984 paper on
Hantavirus seroprevalence in Canada was routed to me as E-mail rather
than as a follow-up post. For those interested, here it is:
Dan McLeod checking in. It is obvious that in Canada it takes a paper
10
years to be relevant. Pity. Too many epidemiologists!
There seems to be some question here w.r.t. the antibody assay used and
its relevance. When it comes to ascertaining antibodies that will
protect
in case of infection, neutralizing antibody to a surface glycoprotein on
the virion is without doubt the gold standard. These antibodies
neutralize
the infectivity of the virus in a susceptible host. These antibodies
can
also be assayed with the indirect fluorescent antibody technique. In
the
case of the Hantaviruses, the M segment codes for 2 glycoproteins, G1
and G2.
These served as antigen in A549 cells infected with the prototype strain
76-118 and also strain 79-90, whereas NEV was in lung sections of C.
glareolus. Over 2000 sera were tested and 29 (1.4%) were positive
with tires ranging from 1:16 to 1:128.
As a point of interest, there were only 2 patients with titres of 1:128.
One was a 57 year old female from Alberta and the other was a 72 year
old
female from Ontario. Antibody was found in all provinces. This
antibody
indicates contact with a Hantaan-like virus. The current strains with a
pulmonary syndrome are more related to the Prospect Hill virus. Its
obviously time to do some more testing for relevant antibody. The
specific virus in the Alberta case can be identified from patient
samples using a nested set RT-PCR with G2 consensus primers and
sequencing
the amplicons for comparison to the 4 Corners strain, etc.
BTW, the ELISA test appears to using nucleocapsid protein expressed in
E.coli as per Zoller in JMV 39:3, 1993. This is coded for by the S
segment and is highly conserved and probably useful for screening.
Zoller claims the Elisa to be superior to the indirect
immunofluorescence
assay. Not a bad compliment for the IFA also. It would be even more
strain specific though, if the G protein had been expressed in a
eucaryotic expression system, IMHO.
Now who is doing the RT-PCR on the Alta-Hanta virus?
On 12 Oct 1994, Dr. R. Marusyk wrote:
> Alberta Hantavirus
>>> Unfortunately, the long-established presence of Hantaviruses in these
> parts has been largely ignored. Dan McLeod, now at the Viral Oncology
> Lab at the Laboratory Centre for Disease Control in Ottawa, when he
was
> in charge of the large influenza serum bank at LCDC had supplied sera
to
> H-W Lee (the Hantavirus man) for a retrospective study of the
> seroprevalence of Hantavirus antibody in the Canadian population. That
> study (published in the Canadian Journal of Microbiology in 1984 (30:
> 1137-40) clearly showed that the virus was here.
>However, the powers-that-be declined to fund further investigation as,
in their opinion, the virus DID NOT EXIST in Canada.
Time to try again. Perhaps they have seen the light. :)
Dan McLeod,
National Laboratory for Viral Oncology,
LCDC, Ottawa
<dmcleod at hpb.hwc.ca>
