Conference quark::mennotes-v1

287.0. "Contraceptive Vaccine" by ARTFUL::SCOTT (Wastin' away again) Fri Oct 07 1988 11:40

    
    Reprinted without permission from Thursday's (10-6-88) Boston Globe:

         Success reported in animal tests of sperm vaccine
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         In a study that is viewed as a milestone in contraceptive
         research, a team of Connecticut scientists has shown that an
         antisperm vaccine is 100 percent effective at blocking conception,
         whether used in male or female animals.

         The vaccine, called PH-20, is reversible and causes no apparent
         side effects.  And, since an anti-sperm vaccine does not block
         implantation of a fertilized egg in the uterus but makes sperm
         incapable of fertilizing an egg, it would, in a human version,
         probably avoid the political pitfalls of some other antifertility
         approaches, researchers say.

         Although other contraceptive vaccines are also under development,
         including one called HCG currently being tested in humans in
         Finland, Australia and India by the World Health Organization,
         none has yet been shown as effective as PH-20, which has been
         tested only in guinea pigs.

         Still, researchers say, it could be years before an antisperm
         vaccine is widely available.

         In work to be published today in the British journal Nature,
         researchers at the University of Connecticut, led by Paul
         Primakoff, injected male and female guinea pigs with a synthetic
         version of PH-20, a protein found on the surface of sperm that
         helps sperm penetrate eggs.

         Although the term vaccine has been used mainly to designate a
         substance that stimulates protection against disease, it can also
         mean any substance that triggers an immune response.

         In vaccination, a foreign protein is injected into the body,
         triggering a complex immune response including the formation of
         antibodies that can attack that protein.  In a high dose in a
         vaccine, the body recognizes sperm as a foreign substance.

         An attack on sperm
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         In addition to contraception, the new research is also likely to
         boost research in human infertility, about 2 percent of which is
         caused by a misguided immune attack on sperm, in which either the
         man's or woman's immune system perceives sperm as foreign and
         attacks it.

         The injected females produced antibodies, immune system proteins,
         against PH-20.  When mated with fertile males, none of the
         immunized females conceived.

         The researchers then showed that in the test tube, the females'
         antibodies bound to sperm and kept the sperm from fertilizing
         eggs.

         The immunized females gradually regained their fertility.  Six
         months after vaccination, 17 percent were fertile again; by 15
         months, 100 percent were.

         In the injected males, PH-20 also stimulated an immune response
         which attacked sperm in the testes, where sperm is made.  None of
         the immunized males was able to impregnate fertile females; yet
         after the immune response wore off, the males, too, were again
         fertile.

         And despite the immune attack on the testes, there was no damage
         to tissue.

         Because the antibodies made against the sperm protein are so
         specific, researchers added, they appear safe because they do not
         "recognize" or attack any other cells in the body.

         Toward a sperm protein
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         While the guinea pig protein itself could theoretically be
         tried--and might work some of the time--to prevent conception in
         humans, the more likely path, researchers said yesterday, is to
         develop a human sperm protein.

         That process is under investigation by Erwin Goldberg, professor
         of biochemistry, molecular biology and cell biology at
         Northwestern University in Evanston, Ill.

         Goldberg said yesterday that his team has cloned the human gene
         for a key sperm protein call LDH-C-4 (lactate dehydrogenase C-4)
         and has produced it through genetic engineering.

         They will test it soon as a vaccine in baboons.  Goldberg praised
         the Connecticut team's work as "quite impressive," adding that it
         is all the more remarkable because "there is virtually no support
         these days for contraceptive vaccine work."

         In an article accompanying today's paper in Nature, R.J. Aitkin
         and M. Paterson of the Reproductive Biology Unit of Britain's
         Medical Research Council noted, "of all the methods currently
         being researched, the engineering of contraceptive vaccines must
         be the most exciting."

         The PH-20 data, they add, provide "convincing evidence for the
         feasibility of developing an effective contraceptive vaccine based
         on sperm-specific antigens."