rjh1@midway.uchicago.edu (robert j hinde) (05/04/91)
The recent discussion of how long it takes to seroconvert after
one is exposed to HIV made me wonder if any animal studies had
been done on this subject. For example, one might inject SIV
into a large number of monkeys and then see how long it takes
each one to seroconvert. I know that these observations would
not be directly transferable to humans because of differences
between HIV and SIV and between monkeys and humans, but they
still might provide some interesting information, if only about
the spread of seroconversion times.
So, my questions in a nutshell are:
(1) Are such studies feasible, and if so, have they been done?
(2) Is anything known about how informative such studies would
be with respect to the seroconversion time question in humans?jpcapitanio@ucdavis.edu (John Capitanio) (05/04/91)
In article <1991May3.184320.23916@cs.ucla.edu>, rjh1@midway.uchicago.edu (robert j hinde) writes: >The recent discussion of how long it takes to seroconvert after >one is exposed to HIV made me wonder if any animal studies had >been done on this subject. For example, one might inject SIV >into a large number of monkeys and then see how long it takes >each one to seroconvert. I know that these observations would >not be directly transferable to humans because of differences >between HIV and SIV and between monkeys and humans, but they >still might provide some interesting information, if only about >the spread of seroconversion times. > >So, my questions in a nutshell are: > >(1) Are such studies feasible, and if so, have they been done? >(2) Is anything known about how informative such studies would > be with respect to the seroconversion time question in humans? There is currently a very active series of research programs going on using the SIV-macaque model, which, incidentally, organizations like the World Health Organization and Institute of Medicine consider to be one of the best animal models for HIV-AIDS. Macaques, when inoculated with SIV (which is *not* endemic to this genus), develop a very similar disease course to HIV infection in AIDS. Obviously, the ability to control dose of inoculum, co-infections, and (my area of interest) social conditions, can lead to a very powerful model. As I said, there are several research groups doing such research. None have specifically inoculated macaques with SIV simply to determine latency to seroconversion, but often, these data are reported with those constituing the main thrust of the paper. I am putting together a manuscript which is an archival study looking at the influence of social factors on disease progression in simian AIDS. My data are based on 22 monkeys, inoculated with doses ranging from undiluted SIVmac to 10 to the minus 4 log dilutions. Consistent with other data, no effect of dosage was found to predict latency to seroconversion. In fact, the only variable explaining the variance in this measure was age, paralleling a finding in humans -- animals inoculated at a younger age had shorter latencies. For the 22 monkeys whose data comprise my sample, the median time to seroconversion was 28 days, with a range of 15 to 52 days. One important point to make about the monkey data, is that one of the most consistent findings has been that the strength of the antibody response to the virus correlates strongly with survival; animals who mount a weak antibody response, or none at all, die quickly. Finally, survival is quite variable, like in humans. The median survival time in the 22 monkeys whose data I used was 172 days, with a range of 89-778. Daniel et al. (J. Gen. Virol., 1987, vol. 68, pp 3183-3189), in their seminal paper on persistent infection of macaques by SIV, provide considerable data along these lines. Finally, I might add that my preliminary data indicate that social factors may be important predictors of disease progression. In my archival study, the *only* variable that explained survival duration was the relative frequency that the animals' housing changed -- animals who were moved more frequently showed shorter survival times. I think these data are consistent with the notion advanced by AIDS clinicians that stability of one's life situation is a *good* thing for people who are ill (or at least infected). Hope this has helped. John Capitanio (jpcapitanio@ucdavis.edu) Note: the usual disclaimers apply. Please also keep in mind that this is still work in progress.