Summaries of Presentations at the 32nd Interscience Conference on Antimicrobial Agents and Chemotherapy

Monday, October 12, 1992

10:15 A.M. P.T. (1:15 P.M., E.T.)
Immediate Use of High Doses of AZT May Inhibit HIV Infectivity #58 Oral
A study using the monkeys, Macaca fascicularis, infected with the AIDS-related virus simian
immunodeficiency virus (SIV), suggests that immediate and consistent use of high doses of zidovudine
(AZT) may be effective in treating early infection. The scientists report higher, less frequent doses
were as or more effective than smaller, more frequent doses, which is the current schedule for AZT
administration.
In the study, investigators gave 18 monkeys injections of 100 milligrams (mg.) of AZT per kilogram
(kg.) body weight daily, beginning one day before the monkeys were exposed to SIV. Therapy lasted
for 28 days, with total daily dose of AZT remaining constant, while researchers adjusted dose
concentration and frequency. For comparison, scientists observed six additional SIV-infected
macaques that did not receive AZT.
The researchers followed the monkeys for 140 days. In the six SIV-infected macaques receiving 50
mg. AZT/kg. every 12 hours, SIV could not be detected in one monkey. Four of the six monkeys
persistently had low levels of virus. Other SIV-infected monkeys received 33.3 mg./kg. every 8 hours,
of which two had low virus levels and four had high levels, or 25 mg./kg. every 6 hours, of which all
had high virus levels.
"Effect of Dosing Frequency on AZT Prophylaxis Against Simian Immunodeficiency Virus (SIV) in
Macaca fascicularis," Che-Chung Tsai, D.V.M., Ph.D., R. Grant, R.E. Nolte and C. Bartz, Regional
Primate Center, University of Washington, Seattle; and Polly A. Sager, Ph.D., Developmental
Therapeutics Branch, Division of AIDS, NIAID, Bethesda, Md.
1:30 P.M. P.T. (4:30 P.M. E.T.)
Antibody Therapy Could Protect Newborns from Respiratory Virus #415 Poster
To help prevent infection with respiratory syncytial virus (RSV), infants born at or before 28 weeks of
pregnancy may benefit from receiving protective antibodies. RSV causes significant respiratory
disease among infants, including pneumonia, croup, bronchitis and middle ear inflammations.
Preterm infants may have an increased risk of RSV because the mother's antibodies to the virus may
not completely transfer during pregnancy. In the study, investigators used blood from the umbilical
cord to measure levels of antibodies including IgG, IgG1 and IgG3 in 41 preterm and 49 term infants.
Each of the preterm babies had lower levels of all of the antibodies, as well as amounts of neutralizing
antibodies that would not protect against RSV.
"Respiratory Syncytial Virus (RSV)-Specific Antibodies (AB) in Preterm Infants," T.M. De Sierra,
M.L. Kumar, MetroHealth Medical Center, Cleveland, Ohio; and Brian R. Murphy and E. Kanta
Subbarao of NIAID, Bethesda, Md.

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