chguest@pioneer.arc.nasa.gov (CJG) (11/27/89)
I have been asked to summarize the articles that were sent to me
concerning the viability of HIV when it is not in the human host. I
received several replies and all of them except the following either
skirted the issue or said that if it did live outside that it was of
little or no danger because of studies conducted on the families of
several hemophilliacs. (These studies determined that even people who
used the same living space and at times even the same toothbrush had
not, as of yet, gotten AIDS.)
The most interesting, and the longest response that I received
is included below. It suggests that there may be a possibility of
viability away from the human host. Hope this helps those who wanted a
summarization.
Subject: Questions on the Viability of the Virus Outside of the Body
I am as interested in finding out about such studies as [XXXXXXX XXXXX]
and his callers are. Meanwhile, this is what Gene Antonio's book
has to say about how long the virus can live outside of the body:
The September 28, 1985 issue of the British medical journal _Lancet_
contained a study by a team of French researchers from the Viral Oncology
Unit at the Pasteur Institute revealing that the AIDS virus can remain
infectious outside the body for up to ten days:
LAV/HTLV-III, the agent causing AIDS, has been isolated from body fluids
(blood, semen, saliva, tears). Its isolation in saliva prompted us to
investigate the possibility of transmission by saliva, and we have studied
the sensitivity of LAV/HTLV-III at room temperature. . . . The virus used
for the infectivity assay . . . was left at room temperature for 0, 2, 4,
or 7 days in a sealed tube or allowed to dry in a petri dish. After the
times indicated in the figure the virus was used to infect stimulated T
lymphocytes and viral production was determined in cell-free supernatant
by testing for the reverse transcriptase activity twice a week. [The data]
shows the unusual stability of HTLV-III at room temperature. No signifi-
cant difference was found between 0, 2, or 4 days. Only a slight decrease
is noted with a delay in the virus production indicating a loos of a few
infectious particles after 7 days at room temperature.
Two petri dishes containing 25,000 cpm equivalent reverse transcriptase
of dry virus were kept at room temperature for 4 or 7 days and then re-
suspended in 0.220 ml water and used to measure the infectivity. As [the
data show], significant numbers of viral particles are then inactivated,
but some infectious virus is still present since release of virus was seen
on day 10. This result indicates that the virus is resistant at room
temperature, either in dry form or liquid medium.
This resistance of LAV at room temperature may explain the appearance of
some cases of AIDS cases in non-risk groups. To prevent possible contami-
nation by viral particles in dry or liquid form hygiene should be increased
in the general population. Moreover, some more safety precautions should
be taken in laboratories and in hospitals and by dentists who use a vacuum
pump for saliva aspiration. Indeed, these data strongly support the use of
disinfectants found to be effective against the AIDS agent.
-- F. Barre-Sinoussi et al., "Resistance of AIDS Virus at
Room Temperature," _Lancet_, 28 September 1985, pp. 721-722
Shortly after this study, researchers from the laboratory of Tumor Cell
Biology, National Institutes of Health and elsewhere reported findings on the
stability of concentrated amounts of the AIDS virus:
In view of the serious consequence of HTLV-III/LAV infection, its stability
under clinical and laboratory conditions and its inactivation by commonly
utilized inactivating agents and disinfectants are of tremendous importance
to health care workers and laboratory personnel. Here, the results of
testing the stability of HTLV-II/LAV under various experimental conditions
are reported. . . .
To test the effect of some frequently encountered clinical and laboratory
conditions on the infectivity of the HTLV-III (TM), virus diluted in media
supplemented with 50% human plasma was dried and incubated at 23 to 27
degrees Centigrade, or incubated in an aqueous temperature (23 to 27 degrees
Centigrade), 36 to 37 degrees Centigrade, and 54 to 56 degrees Centigrade
for various periods of time. In a dried state, complete inactivation of
virus required between three and seven days. . . .
Exposing virus to different temperatures resulted in a reduction of
infectious virus corresponding to increasing times of incubation and
increasing temperatures. Complete inactivation . . . of infectious virus
was seen between 11 and 15 days of exposure at 36 to 37 degrees Centigrade.
Infectious virus was still detected after 15 days at room temperature. . . .
Infectious cell-free virus could be recovered from dried material after
up to three days at room temperature, and in an aqueous environment (e.g.,
water), infectious virus survived longer than 15 days at room temperature.
Even under the more rigorous heating conditions commonly used to inactivate
complement (54 to 56 degrees Centigrade), infectious virus was detected
three hours after exposure. . . . The stability of HTLV-III at 54 to 56
degrees Centigrade suggest that the inactivation of virus in blood products
(e.g., antihemophilia factors) could require more extensive treatment, as
has been suggested.
-- L. Resnick et al., "Stability and Inactivation of
HTLV-III/LAV under Clinical and Laboratory
Experiments," _JAMA_ 1985:225:1897-1891.