IAVI Report Vol. 2, no. 2

to be non-pathogenic in newborns. Upon challenge with pathogenic SIV,
protection was only seen in the newborn which had developed high
levels of SIV antibodies.
Researchers from the Aaron Diamond AIDS Research Center
(ADARC) and the Walter Reed Army Hospital each reported that a
monkey immunized with a live-attenuated SIV vaccine has developed signs
of immune deficiency from the vaccine. According to Ruth Connor of
ADARC, data from 20 macaque monkeys given the nef-deleted SIV
vaccine suggests that vaccinated monkeys suppress challenge virus as
early as five weeks after immunization. Full protection occurs in 10 to 15
weeks. Connor also reported that while 19 of the 20 vaccinated monkeys
have undetectable levels of the nef-deleted virus, one monkey has
detectable virus that is increasing in a pattern similar to that seen with
simian AIDS. Mark Lewis of Walter Reed also reported that a monkey
immunized with a nef-deleted vaccine developed AIDS from the vaccine.
New Monoclonal Antibody
Carl Hanson of the California Department of Health in Berkeley
gave an unscheduled talk on a monoclonal antibody (named B4) being
developed by United Biomedical, Inc. of Hauppauge, New York. The
antibody is directed against the complex formed by the interaction
between CD4 and the chemokine receptor, CCR5. The monoclonal
antibody was able to neutralize primary isolates of HIV, as well as HIV-2,
SIV and SHIV. Moreover, HIV was inhibited even when the antibody was
added up to 24 hours after infection of cells. In addition, the monoclonal
antibody protected SCID mice from challenge with HIV when it was
administered four hours after challenge. Hanson also reported that this
monoclonal antibody was non-toxic to cells. He suggested that B4 could
be used for post-exposure prophylaxis and that a possible vaccine
approach would be to try to elicit the same antibody specificity with
a candidate vaccine.
continued on page 11

Reports Suggest that Antibodies
to Goat Virus "Neutralize" HIV
by David Gold
Among the more talked about presentations at the
NCVDG Meeting was a report by University of Southern
California (USC) researcher Angeline Douvas that a goat
virus, which appears to be harmless to humans, may protect
against HIV infection. According to Douvas, humans
infected with novel variants of a virus known as caprine
arthritis encephalitis virus (CAEV) often develop antibodies
capable of neutralizing HIV.
Like HIV, CAEV, is a lentivirus. It is extremely common in
goats and can cause a broad range of illnesses in these
animals. However humans, who are usually infected with
CAEV by ingesting raw goat milk, do not appear to get sick
from the virus.
CAEV viruses were first identified in humans diagnosed
with mixed connective tissue disease (MCTD), an immune
deficiency that causes symptoms similar to lupus. But
according to Douvas, CAEV is not connected to MCTD.
In Mexico, up to 40 percent of children in some areas are
infected with a CAEV-related virus. It is not certain
whether humans can infect one another with the virus, but
in lab tests, CAEV isolated from human plasma can infect
cells from other humans.
Douvas first became interested in the potential for CAEV
as an AIDS vaccine when she learned that some Mexican
MCTD patients tested positive for HIV antibodies even
though they were not infected with HIV. The USC
researcher then found that CAEV antibodies were capable
of "substantially neutralizing HIV-I." In addition, Douvas has
identified one patient who appears to be co-infected with
CAEV and HIV. This patient reports that he has been HIVpositive for at least 15 years, without any apparent sign of
immune suppression.
In her presentation, Douvas suggested that CAEV-related
viruses could potentially be used as a live-attenuated AIDS
vaccine. The immunity elicited by such vaccines could be
increased by creating a combination CAEV/HIV or
"chimeric" virus (CH IV).
Douvas told the IAVI Report that her lab has already
developed a CHIV virus for testing in monkeys. They
recently attempted to infect a monkey with CAEV and are
monitoring the monkey biweekly to see if infection occurs.
Carl Dieffenbach, associate director of NIlAID's Basic
Science Program, has been following the CAEV research
closely from the beginning. He believes that the findings
are "potentially very exciting." However, Dieffenbach

suggests that an important step for Douvas will be to
"biologically characterize the apparent novel variants of
CAEV in humans."*

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