Biology Reference
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of transmission for HIV-1 is through mucosal surfaces, efforts have
been made to evaluate the efficacy of antibodies for protection against
a mucosal challenge. 102 As with systemic challenge, it was demon-
strated that complete protection from mucosal challenge was
obtained in a majority of animals that received a triple antibody com-
bination (HIVIG/2F5/2G12) (Fig. 6B); however, two out of five
animals that received a double combination (2F5/2G12) and two out
of four animals that received 2G12 alone were protected against the
challenge infection, once again indicating that breadth of the immune
response is critical for the protective efficacy (Fig. 6B). To address
post-exposure use of neutralizing mAb, Nishimura and colleagues
asked the question how soon after virus exposure neutralizing anti-
bodies must be present to block an SIV/HIV chimeric virus infection
in pig-tailed macaques. 105 They demonstrated that sterilizing immu-
nity can be achieved in 75% of the animals that received neutralizing
IgG six hours after intravenous SIV/HIV chimeric virus inocula-
tion, 105 suggesting that antibodies of appropriate specificity have not
only prophylactic but also have therapeutic application.
Ruprecht and colleagues have performed several studies to evalu-
ate the role of neutralizing antibodies in preventing mother-to-infant
transmission of virus. 106-108 They demonstrated that passive transfer of
a mAb cocktail (F105, 2F5, and 2G12) completely protected preg-
nant mothers against intravenous SHIV-vpu + challenge after delivery.
The infants subsequently born to these infected mothers who
received the mAbs indirectly across the placenta from their mothers
and received another dose of antibody cocktail followed by oral chal-
lenge with SHIV-vpu + were also completely protected against the
infection. 106 Subsequent experiments have demonstrated that it was
possible to protect neonates against a highly pathogenic SHIV 89.6P
challenge by passive infusion of a mAb cocktail containing F105, 2F5,
2G12, and b12. Another infusion of the same mAb cocktail an hour
after the virus exposure, followed by another dose on day eight, com-
pletely protected animals against infection. 106,109 In a recent study,
Ferrantelli et al . 110 demonstrated complete protection of neonatal rhe-
sus macaques against exposure to pathogenic simian-human immun-
odeficiency virus (SHIV) by human anti-HIV mAbs. In this study,
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