HICNet Medical News Digest Sun, 02 Jan 1994 Volume 06 : Issue 59 Today's Topics: AIDS Daily News Summaries +------------------------------------------------+ ! ! ! Health Info-Com Network ! ! Medical Newsletter ! +------------------------------------------------+ Editor: David Dodell, D.M.D. 10250 North 92nd Street, Suite 210, Scottsdale, Arizona 85258-4599 USA Telephone +1 (602) 860-1121 FAX +1 (602) 451-6135 Compilation Copyright 1994 by David Dodell, D.M.D. All rights Reserved. License is hereby granted to republish on electronic media for which no fees are charged, so long as the text of this copyright notice and license are attached intact to any and all republished portion or portions. The Health Info-Com Network Newsletter is distributed biweekly. Articles on a medical nature are welcomed. If you have an article, please contact the editor for information on how to submit it. If you are interested in joining the automated distribution system, please contact the editor. E-Mail Address: Editor: Internet: david@stat.com FidoNet = 1:114/15 Bitnet = ATW1H@ASUACAD LISTSERV = MEDNEWS@ASUACAD.BITNET (or internet: mednews@asuvm.inre.asu.edu) anonymous ftp = vm1.nodak.edu Notification List = hicn-notify-request@stat.com FAX Delivery = Contact Editor for information ---------------------------------------------------------------------- Date: Sun, 02 Jan 94 08:55:35 MST From: mednews (HICNet Medical News) To: hicnews Subject: AIDS Daily News Summaries Message-ID: AIDS Daily Summary The Centers for Disease Control and Prevention (CDC) National AIDS Clearinghouse makes available the following information as a public service only. Providing this information does not constitute endorsement by the CDC, the CDC Clearinghouse, or any other organization. Reproduction of this text is encouraged; however, copies may not be sold, and the CDC Clearinghouse should be cited as the source of this information. Copyright 1993, Information, Inc., Bethesda, MD "Merck Steps Up Work on an AIDS Drug Following 'Promising' Initial Trials" Wall Street Journal (12/20/93) P. B5 (Waldholz, Michael) Because initial human trials of an experimental AIDS drug proved promising, Merck & Co. plans to step up its development of the drug, known as L-735,524. The drug blocks the activity of an enzyme that is essential for HIV replication. Scientists believe that deactivating the enzyme, known as protease, can prevent the virus from spreading beyond an infected cell. In recent years, several companies have developed drugs which block protease activity, but those therapies have proven unsuccessful outside of the laboratory. Merck's several small trials, however, indicate that daily oral doses of L-735,524 achieved levels in the blood considered high enough to affect viral replication--one of the major shortcomings of earlier efforts. In addition, one study of 10 AIDS patients found that administration of the Merck drug reduced the amount of measurable virus in patients' bloodstreams by 70 percent. Company officials do caution that the trial results, though encouraging, are still very preliminary. They are also cautious, for fear that new, prolonged studies may show that use of L-735,524 may produce drug- resistant strains of HIV. "Initial Clinical Results for New AIDS Treatment Reported" PR Newswire (12/14/93) Rockville, Md.--Advanced Biotherapy Concepts, Inc., has completed initial clinical testing of a innovative new AIDS therapy. The treatment is different in that, instead of HIV, it targets an unusual form of alpha interferon that is affiliated with HIV disease progression and advancement to AIDS, and may also be linked to HIV replication. The procedure passes a patient's plasma through an extracorporeal immunosorbent column containing antibodies that neutralize and capture the interferon. The process was tested on four patients during the trial conducted at the University of Nebraska Medical Center. The procedure, conducted in five consecutive daily treatments, was well-tolerated by all four patients, and the device successfully absorbed interferon from the patients' plasma. Two patients showed reduced HIV viral loads in their plasma after treatment, and two displayed a significant reduction in tumor necrosis factor--a known HIV indicator. The initial study is the first phase in the development of the research company's anti-cytokine therapy for AIDS, said Dr. Simon Skurkovich, president and founder of Advanced Biotherapy Concepts, Inc. He said that by adding other antibodies to the absorption device, the procedure could be used to remove any combination of cytokines implicated in HIV replication and immune dysregulation in AIDS. The company is now preparing a submission to the Food and Drug Administration for permission to expand testing and remove other cytokines. "CDC Tries Preventing AIDS by Tailoring the Message" American Medical News (12/13/93) Vol. 36, No. 46, P. 17 The U.S. government is searching for new ways to increase condom use as a means of preventing the spread of AIDS. A survey of some 700 clinic patients treated for sexually transmitted diseases found that most, while not using condoms, were considering them. The government's aim is to tailor counseling so as to reach those who can be convinced to protect themselves-- for example, women who are hesitant to discuss condom use with their primary sex partners. In that study, far more women than men were in the "contemplative" stage, meaning they were considering regular use of a condom with their main partners. Men, however, were in the "precontemplative" phase, meaning they rarely used condoms and harbored no intention of using them on a regular basis. "We've tried simple educational messages and suspect that they're not very helpful," said Mary Kamb, an epidemiologist at the Centers for Disease Control and Prevention. "But maybe we have not been approaching counseling correctly." She said the next study will enroll 6,000 people across the nation to compare the effectiveness of the broader AIDS prevention with tailored messages to increase condom use. "Montagnier's AIDS Report Covers All Angles" Nature (12/09/93) Vol. 366, No. 6455, P. 496 (Butler, Declan) Luc Montagnier of the Institut Pasteur in France, assigned to assess the French battle against AIDS, recently presented prime minister Edouard Balladur with a comprehensive review full of sensible, and surprising, recommendations. Much of the report proposes changes to the National AIDS Research Agency (ANRS), which Montagnier denounced as a "ghetto" with no sufficient ties to other areas of scientific research or AIDS programs. He recommends that the agency be absorbed into INSERM, the national medical research organization. He also suggests that the agency establish a fund of several million dollars to support non-mainstream AIDS research. In addition, the report recommends that all AIDS patients be allowed access to promising drugs before they are approved, but suggests investigations into illegal clinical trials. Montagnier also urges the government to create an interministerial committee to coordinate all efforts against the epidemic, including research. Only one-tenth of the report, surprisingly, addresses research issues. The rest touches on prevention, health-care, training, and the special problems surrounding drug addicts, prisoners, and women. These areas required Montagnier to engage in extensive consulting, raising speculations that he may be angling for a position as national AIDS coordinator. "Breast Feeding and HIV" Lancet (12/11/93) Vol. 342, No. 8885, P. 1437 (Ziegler, John B.) Breast feeding has been identified since 1985 as a means of transmitting the AIDS virus from an infected mother to her infant. In developed countries, most women who are aware of their HIV-positive status at the time of delivery will choose not to breast feed. In Africa, where breast feeding is crucial to child survival, HIV-infected mothers will breast feed anyway. This may, therefore, account for the high rates of perinatal transmission that are found in sub-Saharan countries as opposed to in Europe. The alternative is bottle feeding, which is dangerous as well. The World Health Organization and UNICEF recommend that all mothers, including those with HIV, in environments where there is a high rate of infant mortality associated with infectious disease or malnutrition breast feed their babies. The consensus seems to be that both bottle and breast feeding can pose some risk for HIV transmission. So which method should a mother choose? A simple comparison of the risks of mortality from infection linked to bottle feeding and the risks of contracting HIV through breast feeding would offer some guidance about which method to choose, but such data is not yet available. Until this information is known, it is best to try to determine the risk of bottle feeding vs. that of acquiring HIV during breast feeding for each infant using the estimate of 1 in 7 for the latter. Even in areas where infants die of infectious diseases, some mothers may still be able to bottle feed safely. "Newly Approved Drug Fights Pneumonia Related to AIDS" Washington Post (12/21/93) P. A4 The Food and Drug Administration has approved a new treatment to help AIDS and otherwise immunocompromised patients combat pneumocystis carinii (PCP), a deadly pneumonia parasite. U.S. Bioscience has been given permission to market trimetrexate glucuronate as an alternative therapy for PCP which, as the most common life-threatening infection linked to AIDS disease, affects as much as 80 percent of the AIDS population. The intravenous drug, assigned the brand name of Neutrexin, must be taken simultaneously with a second drug called leucovorin. The second drug protects normal cells while the trimetrexate attacks the parasite, which invades the lungs of AIDS patients. According to FDA spokesperson Arthur Whitmore, Neutrexin is "another weapon in the arsenal" against AIDS. There are currently three other drugs to fight PCP on the market. U.S. Bioscience said that candidates for Neutrexin include the estimated one-third to one-half of AIDS patients who must stop taking one of the other three treatments, trimethoprimsulfamethoxazole, because of adverse side effects. Patients taking the new drug must consult frequently with doctors and have blood counts monitored twice weekly. Related Story: Philadelphia Inquirer (12/21) P. C1 "Modest Advances Seen With 2 AIDS Drugs" New York Times (12/21/93) P. C7 (Altman, Lawrence K.) Researchers have reported modest advances in drug treatment of two common and serious complications of AIDS. The first is an improvement in the oral form of the drug ganciclovir, which is being developed to treat cytomegalovirus (CMV) retinitis, a potentially blinding eye infection. Researchers found that enough of the oral form of ganciclovir got into the body to suppress growth of CMV significantly without many adverse side effects. Current drug therapy for CMV retinitis is intravenous only and requires the patient to keep a tube in place of a vein, so the oral form of the drug carries strong promise of a better lifestyle for these patients. The other advancement was observed in fluconazole, a drug to treat invasive and superficial fungal infections in AIDS patients. Most recent studies showed that fluconazole delayed the onset of fungal infections in AIDS patients with CD4 counts under 200, doing so notably better than another drug called clortrimazole. The two advancements were reported at a scientific meeting in Washington, D.C., sponsored by the National Foundation for Infectious Diseases and the American Society for Microbiology. "Cryopharm Demonstrates Potent Viral Decontamination of Blood Products" Business Wire (12/17/93) Pasadena, Calif.--CP-38, the proprietary psoralen molecule of Cryopharm Corp., has demonstrated its ability to eliminate platelets, which are critical human blood components of viral contaminants--including HIV. When added to human platelet concentrates, CP-38 reduced model viruses by as much as 1 million-fold compared to untreated samples. There was little effect on the function of platelets, which are essential to clotting. Psoralens are naturally occurring molecules that insert themselves into viral nucleic acids, a fundamental component of all viruses. Because red blood cells and platelets do not contain nuclear DNA, they are virtually unaffected by CP- 38. Once the compound is entwined in the nucleic acid backbone of the DNA helix and exposed to ultraviolet light, a chemical reaction occurs that breaks the two backbones of the helix, thus completely inactivating the virus while sparing the surrounding blood cells. Studies have shown the compound to be non-toxic at sufficient levels to achieve maximum viral inactivation. "Given the growing international concern about the safety of human blood products, we believe that Cryopharm's viral inactivation technologies may offer a simple, efficient, and cost-effective method to significantly increase the safety of these products from blood-borne viruses such as HIV and hepatitis," said Carl E. Brooks, president and chief executive officer of Cryopharm. "CDC to Launch New HIV Prevention Initiatives" American Medical News (12/13/93) Vol, 36, No. 46, P. 10 (Staver, Sari) The Centers for Disease Control and Prevention, in response to an independent panel's critical review of HIV-prevention programs administered by the federal agency, announced several new initiatives. The first is a new public-information campaign called a "prevention marketing initiative" that will target people under age 25 who are practicing unsafe sex. The program, set to kick off before the end of the year, will include a national media campaign and demonstration projects conducted jointly with local groups. In addition, a new public-service campaign will be launched. This initiative will feature explicit messages about preventing sexual transmission of HIV, which are scheduled for broadcast at the beginning of next year. The third initiative, effective as of Jan. 1, involves proposed new procedures for review of federally funded AIDS-prevention materials. Under the policy, recipients of CDC money to produce or distribute such material will be able to designate local groups to review them. It will, therefore, no longer be necessary to have materials reviewed by government-appointed groups, which has been an instrumental factor in blocking the distribution of sexually explicit materials. "A Prospective Study of Diarrhea and HIV-1 Infection Among 429 Zairian Infants" New England Journal of Medicine (12/02/93) Vol. 329, No. 23, P. 1697 (Thea, Donald M. et al.) AIDS is often characterized by persistent diarrhea in adults, but the cause and its effect on HIV-infected children is still largely unknown-- especially in Africa, where it is the leading cause of mortality among children with HIV. Thea et al. conducted a study of 429 infants in Zaire born to both HIV-positive and HIV-negative mothers to determine the incidence of persistent diarrhea. HIV-infected infants, compared to uninfected babies, had greater incidence rates for acute, recurrent, and persistent diarrhea. Persistent diarrhea developed in 11 infected babies, all but one of whom died. It also developed in 19 uninfected infants, all but one of whom survived. Using a multivariate model, Thea et al. found that persistent diarrhea was independently linked with symptomatic HIV infection in the mother. The incidence of persistent diarrhea in uninfected babies born to HIV-positive mothers was nearly double that of uninfected infants born to HIV-negative mothers, and the risk increased if the mother died, even among uninfected offspring. Notable growth impairment, bouts of acute diarrhea, and severe immunosuppression often preceded the onset of persistent diarrhea. The data indicates that maternal health is an important risk factor for diarrheal morbidity in infants. Thea et al. propose that diarrheal morbidity was associated with the ability of the mother to care for her baby and maintain infant hygiene and nutrition. The implication, say the researchers, is very important considering the estimated 5.5 million AIDS orphans that will be living in Africa by the turn of the century. "Expanded IND for AIDS Immune Reconstitution Cell-Transfer Therapy Submitted to FDA" Business Wire (12/21/93) Fort Lauderdale, Fla.--Center for Special Immunology (CSI), a subsidiary of Health Professionals Inc. (HPI), has submitted an Investigational New Drug Application to the Food and Drug Administration for a Phase I clinical trial of its Immune Reconstitution Cell-Transfer Therapy. The treatment involves monthly infusions of licensed human intravenous immune globulin followed by closely-matched peripheral blood lymphocytes from an HIV-negative donor, generally a close relative. The patient is usually in the late stages of AIDS disease, and is maintained on antiretroviral and prophylactic therapy against opportunistic infections. The results of a pilot clinical program provide some support for expanded study. "The Immune Reconstitution Treatment Program was developed by physicians affiliated with CSI in an effort to help their patients with late stage AIDS who had failed conventional therapies and for whom there was no acceptable alternative therapy," said HPI's chairman and CEO, William M. Reiter. "Cell transfer and expansion therapies have the potential to fill an urgently needed and critical role in evolving AIDS therapies." "Stalking a Vaccine" Washington Technology (12/02/93) Vol. 8, No. 17, P. 25 (Brendler, Beau) While most potential AIDS vaccines focus on the outer "envelope" of HIV made up of proteins and able to change 1,000 faster than the second fastest virus, Cel-Sci Corp. of Alexandria, Va., is taking an out-of-the-mainstream approach. The company's vaccine, HGP-30, was the first in the world to concentrate on the core of HIV, but is still a relative unknown. It is based on a protein in the core of the virus that does not change throughout its strains and is a synthetic copy of the core protein so that it cannot cause AIDS in healthy people. Early trials indicated that the vaccine produced killer T-cells, which destroy AIDS-infected cells before they take over the body. Other studies observed immune responses triggered by the vaccine. In addition, blood immunized with the drug and placed in mice without an immune system showed a 75 percent rate of protection. Cel-Sci has entered into a joint venture with Alpha 1 Biomedicals to oversee the AIDS research. "Buckeyballs and HIV" Discover (12/93) Vol. 14, No. 12, P. 22 Buckyballs, soccer ball-shaped molecules fascinating scientists around the globe, and HIV, the virus that leads to AIDS, seem an unlikely pair. But researchers at the University of California at San Francisco claim buckyballs are able to cripple the enzyme machinery essential for the AIDS virus to reproduce. Buckyballs could possibly act as inhibitors of HIV protease, an enzyme of the virus necessary for HIV replication. Simon Friedman, a graduate student of chemistry at UCSF, decided to test the idea by using modified buckyballs, called fulleroids, to enable himself to work in the aqueous environment of a living cell. When he mixed a solution of fulleroids with HIV protease, he found no evidence that the HIV protease had been clipping the original polyprotein in two, as it should have been doing. Researchers at Emory University decided to expand the experiment. They discovered that fulleroids actually block HIV from reproducing in cultures of infected white blood cells, without harming healthy cells. Whether buckyballs will ever be developed into a practical treatment for AIDS is uncertain, for many other substances have been shown to disable HIV in the lab. The true test is whether buckyballs can do the same, and do so safely, in the human body of a person infected with the AIDS virus--a question that will take years to resolve. "Medical Briefs" Advocate (12/28/93) No. 635, P. 36 Upjohn Laboratories has produced a drug that has been found in the laboratory to be an effective HIV-inhibiting protease during the late stages of viral replication. The drug, U-75875, dramatically decreased HIV replication in both monocytes and chronically infected cells. Other drugs tested were only effective in newly infected cells. A report on the study proposes that the use of protease inhibitors alone or with another drug is important for HIV therapy. "Pharmacists' Role in Preventing and Treating HIV Infection" American Pharmacy (12/93) Vol. NS33, No. 12, P. 38 (Noormohamed, Saleem and Ferguson, Kristi) Pharmacists are among the most accessible and most respected of health care professionals. Because they are knowledgeable about drugs and educated to endorse health and prevent disease, pharmacists are perfectly poised to have a positive influence on the AIDS epidemic. They do, in fact, have several roles in the fight against the disease. First and foremost, pharmacists must provide accurate and up-to-date information. In addition, they need to monitor drug therapy in both hospital and outpatient environments, including agents that are obtained on the black market, vitamins and minerals, and other unsubstantiated cures and treatments that a patient might be taking. It is also critical that pharmacists counsel HIV patients on proper condom use, as well as educate the public on how the virus is transmitted and what behaviors are risky. It is equally imperative that pharmacists encourage AIDS testing for all individuals who may be at risk for the virus. Finally, ethical guidelines that apply to other health care professionals also apply to pharmacists, who must keep all patient information completely confidential. In general, pharmacists must promote the best possible health care for infected patients. "Counseling Adolescents for HIV Testing Takes Time, Insight" AIDS Alert (12/93) Vol. 8, No. 12, P. 186 More and more adolescents are voluntarily seeking HIV testing. Denial and an inability to fully comprehend the consequences of an HIV test may demonstrate the need for several counseling sessions. Topics of discussion should include the differences between HIV and AIDS, how the virus affects the immune system, how appearance does not reflect infection, the difference between confidential and anonymous testing, state testing and reporting laws, and how unprotected intercourse is the primary means of transmission. The main goal of counseling is to develop a rapport with the adolescent, who may be discussing these issues with an adult for the first time, and to eliminate myths that adolescents may have, the most common of which are that an HIV- positive test result means immediate death and that only "bad" people become infected. Counselors must also assess a patient's frame of mind and support system. If there is a risk of the adolescent becoming suicidal, then it is better to wait. Delivering positive test results requires straghtforward communication--although supportive and caring--and the counselor should be prepared to help the patient verbalize feelings and avoid destructive ways of acting out anger, fear, and helplessness.J Grief, coping, risk reduction, and empowerment are the main issues faced after the test. "HIV Transmission: Women's Risk from Bisexual Men" American Journal of Public Health (12/93) Vol. 83, No. 12, P. 1757 (Wood, Robert W. et al.) A recent analysis of AIDS surveillance data by the AIDS Prevention Project of the Seattle-King County Department of Public Health in Washington state found that men identifying themselves as bisexuals and men identifying themselves homosexuals differed in several ways. The study, which involved 5480 men who reported having sex with another man since 1977, found that self-reported sexual identity was an important indicator of sexual encounters with women and HIV positive status. Of the sample, 77 percent said they were gay and reported almost no sex with females in the past year. Thirteen percent said they were bisexual, and 8.4 percent identified themselves as straight. Self-described gays had the highest rate of HIV seroprevalence. Straight-identified men reported the highest number of female partners and were less likely to be infected, although the seroprevalence was still disturbingly high. Men calling themselves bisexuals, however, posed the most risk of HIV infection to women, while gays and straights exposed equal numbers of women. Bisexual men and straight men were also more likely to inject drugs, a contributing element to the AIDS epidemic. The study suggests that increased attention should focus on men who have sex with men and use intravenous drugs. "A Slippery Defence Against HIV" Lancet (12/18/93-12/25/93) Vol. 342, No. 8886/8887, P. 1500 (Thompson, Clare) Mucosal-associated lymphoid tissue accounts for the largest area of immunologically active tissue in the body, the busiest of which is mucosa of the gastrointestinal tract, which is perpetually dealing with pathogens picked up in food. Ways of using this area for host defense have not been extensively explored, but the possibilities for immunotherapy against diseases of the mucosal surface are significant. One of the most exciting new applications is a possible vaccine for HIV. Lehner et al. theorize that stimulation of secretory IgA in the body areas most at risk for HIV transmission, such as the vaginal, rectal, and genitourinary mucosa, will prevent the virus from crossing the epithelium and entering the immunologically active area below. The researchers also hope for a general action on mucosal-associated lymphoid tissue. If their theory is correct, IgA antibodies directed at the gut could produce secretory IgA antibodies in the respiratory, salivary, and genital areas, as well as other mucosal sites. While they sound promising, one must view these theories with caution. The strategy depends heavily on at least one crucial factor: if the vaginal, rectal, or genital epithelium is torn in any way, increased secretory IgA will be fruitless. If the primed T and B cells in the epithelium act as a second line of defense, however, the future of mucosal vaccination is even more promising. "Clinical Manifestations of AIDS in the Era of Pneumocystic Prophylaxis" New England Journal of Medicine (12/23/93) Vol. 329, No. 26, P. 1922 (Hoover, Donald R. et al.) Pneumocystic carinii pneumonia once occurred in as much as 75 percent of the AIDS population. Prophylactic regimens against the infection are not known to alter HIV or immune function, nor do they protect against other AIDS-related conditions--except toxoplasmosis--or directly alter the patho- psychologic processes leading to other AIDS-related illnesses. By preventing or delaying death from p. carinii pneumonia, however, prophylaxis does shift the clinical manifestations of HIV infection from p. carinii pneumonia to illnesses that occur when immune function is more suppressed. Researchers must now determine what other AIDS-related conditions should be targeted for further prophylaxis and treatment. Hoover et al., therefore, conducted a study of 844 men with AIDS. The results indicated that prophylaxis could delay the onset of the first AIDS-related illness by six months to a year. The study also concluded that only four--myobacterium avium, esophagus candidiasis, wasting syndrome, and cytomegalovirus disease--out of thirteen AIDS-related conditions were observed to surface more often in patients who received prophylaxis against p. carinii pneumonia than in those who did not. "Zidovudine in Asymptomatic HIV Infection" New England Journal of Medicine (12/16/93) Vol. 329, No. 25, P. 1895 (Phillips, Andrew N. and Saben, Caroline A.) Cooper et al. conclude that the benefits of zidovudine last more than two-and-a-half years in asymptomatic HIV patients with CD4 counts over 400. Andrew Phillips and Caroline Saben of the Royal Free Hospital School of Medicine in London question the validity of Cooper et al.'s "on treatment" approach to analysis, in which data were censored three months after the end of blinded treatment. This approach, say Phillips and Saben, should be supplemented with analyses in which follow-up information is not censored. These analyses should consider the original primary end point for the trial-- AIDS--as well as end points later adopted. Cooper et al. do not even acknowledge whether AIDS developed by the end of the trial in approximately half of the subjects, 308 of whom withdrew, note Phillips and Saben. The implied tendency of patients about to reach an end point to withdraw from the trial, they speculate, could actually have created a bias in favor of zidovudine. Given the widespread belief that the drug's effects are limited, any suggestion that this time frame is longer should be supported with the demonstration of a statistically significant difference in risk between zidovudine and a placebo, considering the number of years at risk following two years of treatment. The small number of patients with end points after longer than two years cast doubt, say Phillips and Saben, that such a difference was ever present. Therefore, they conclude, the suggestion that the beneficial effects of zidovudine last longer than two-and-a-half years is not justified based on the results presented. "Biaxin Listed as Treatment for AIDS-Related Infection" Wall Street Journal (12/29/93) P. B4 Abbott Laboratories Inc. of Abbott Park, Ill., has received approval from the Food and Drug Administration to offer its antibiotic Biaxin as a treatment for disseminated mycobacterium avium complex (MAC), an AIDS-related condition. Disseminated MAC is the most common systemic bacterial infection observed in AIDS patients. According to Abbott, Biaxin, the brand name for clarithromycin, is the first drug to receive FDA permission to treat the infection. The company reported study results indicating that Biaxin reduces the MAC organism in the blood. ""Renegade" HIV Immunity Hypothesis Gains Momentum" Lancet (12/18/93-12/25/93) Vol. 342, Nos. 8886 & 8887, P. 1544 (Horton, Richard) American AIDS researchers face a dilemma. Recent evidence suggests that billions of dollars spent developing vaccines based on HIV envelope proteins may have been wasted as scientists abandon these candidates in favor of cell- mediated immunity (CMI) approaches. Gene Shearer of the National Cancer Institute recently presented results which imply that individuals exist who have been exposed to HIV, but remain seronegative. Shearer offers four possible explanations. First, there never was an infection, so CMI is irrelevant. Second, there was infection, but the virus died. Third, virus was present, but was destroyed through cell-mediated immunity. Finally, CMI controlled viral infection. Shearer concluded that previous exposure to small doses of the AIDS virus shields against infectious inoculums of virus through CMI. These conclusions were supported by evidence from a recombinant gp160 trial indicating that low-dose antigen exposure selectively activates CMI and not antibody production. Shearer further determined that strong CMI combined with a dominant type I cytokine profile, is critical in delaying progression to AIDS. ------------------------------ End of HICNet Medical News Digest V06 Issue #59 *********************************************** --- Editor, HICNet Medical Newsletter Internet: david@stat.com FAX: +1 (602) 451-6135 Bitnet : ATW1H@ASUACAD ******************************************************************************