(美国阿拉斯加州播音）

World Christian Broadcasting

Shortwave Radio Station KNLS, Anchor Point, Alaska, USA

Recording Studios: Franklin, Tennessee, USA

在二〇〇五年三月十二日，由中国科学家研制的第一个艾滋病疫苗在人体身上的实验正式开始。有8名志愿者参加了临床一期第一阶段的试验。因初步的结果令人满意，第二阶段的试验于五月十四日又在6名志愿者身上开始进行。全国的大众媒介纷纷报道，欢呼这一防治艾滋病的新希望。

至二〇〇四年底，中国已有将近一百万人被艾滋病毒感染，有八万人发病，艾滋病毒的流行尚在各大城市加速蔓延。面对这一严峻局面，广大群众对新诞生的艾滋病疫苗抱有过分乐观的态度，这是可以理解的。但作为一名从事过艾滋病毒研究工作的科学家，我想提醒公众要警惕艾滋病疫苗所能产生的负面效果。

人体可以通过两条途径得到对某种传染病的免疫力。第一是通过患病来得到。例如，人患过麻疹之后，因为麻疹病毒在患者身上所引起的免疫反应，患者的体内就产生了专门对抗麻疹病毒的抗体和能记住麻疹病毒的淋巴细胞。人就不会再次患麻疹。第二是通过接种疫苗来得到。还以麻疹为例，麻疹病毒结构中的一部份，或是蛋白或是DNA，可以被用作疫苗给健康人接种。人体对麻疹的这一部份结构产生类似于对全麻疹病毒一样的免疫反应，也会产生专门对抗麻疹病毒的抗体和能记住麻疹病毒的淋巴细胞。使得人体在受到麻疹病毒的挑战时，不致于生病。

现在实验中的这个疫苗是通过把艾滋病毒的部分基因（或DNA）装入天花病毒的载体而制成的。这是因为单有艾滋病毒DNA所产生的免疫反应不够强。疫苗中艾滋病毒的DNA是从正在广西流行的天然艾滋病毒中分离加工而来的。这个疫苗起到防治艾滋病作用的前提是流行的天然艾滋病毒DNA不再发生变异。否则，疫苗所引起的抗体和淋巴细胞就不能识别和抵抗流行中的天然艾滋病毒。不幸的是，艾滋病毒在流行中十分频繁地改变自己的DNA，使其有能力对防治措施产生抵抗力。从一九八七年至今，先后已有三十多个艾滋病疫苗进入临床试验，没有一个可以使用，其主要原因就在这里。

我曾目睹艾滋病毒非凡的变异能力。在俄克拉何马医学基金会的实验室工作时，我把一个有治疗作用的基因先放到了人的T淋巴细胞中。然后，我再加入艾滋病毒，看一看艾滋病毒是否仍能感染这些细胞并在其中大量繁殖。这个治疗基因对艾滋病毒的抑制仅仅持续了七天的时间。七天之后，艾滋病毒便一如继往，开始在这些细胞内大量地繁殖。这里，艾滋病毒面对抑制因素，不断地改变自己的基因或DNA序列，直到产生一株有抵抗效果的病毒。

另外，一篇发表在二〇〇五年三月二十二日《美国科学院院报》（Proceedings of the National Academy of Sciences U. S. A. 2005 Vol. 102: 4512-4517）上的研究报告表明，即使在该类疫苗引起满意的免疫反应，艾滋病毒也没有DNA变异的理想条件下，接受疫苗的人却还是被艾滋病毒感染了。一位原先是艾滋病毒阴性的男子，接受了由艾滋病毒和天花病毒重组DNA制成的艾滋病疫苗，经过一年的临床观察，各种对疫苗的免疫反应指标均达到了预期的目标。在这位志愿者的身上不仅有高浓度的抗体，还有专门识别和抵抗艾滋病毒的T淋巴细胞以及有记忆功能的淋巴细胞等等。但在疫苗接种的两年半之后，这位男子因一次同性恋性质的性行为而变为艾滋病毒阳性，也立刻成为这些美国国立卫生院免疫学实验室科学家们的研究对象。麦克尔百赐博士（Michael Betts）和同事发现疫苗所引起的免疫反应仍完好无损，而且，感染他的艾滋病毒有与疫苗一致的DNA，正是疫苗应该防止的那一株。更令人惊异的是，疫苗不但没有防止艾滋病毒的感染，还使他的艾滋病进程大幅度地加快。在这些实验证据的面前，研究人员只得对用疫苗来预防艾滋病毒感染的可行性提出质疑。

艾滋病疫苗所带来的负面效果不只限于个体，还可能涉及社会。一说到疫苗，人们的相信程度普遍很高，这是因为防治其他疾病的疫苗大多有百分之百的效果。与之相比，艾滋病疫苗的有效性即使在理想的情况下也低得可怜。领导艾滋病疫苗临床试验的于晓方教授承认，此艾滋病疫苗如能有30%的预防效果就算是成功的了。这与广大公众的感觉相差很远。我担心，许多人会错误地以为有了艾滋病疫苗就万事大吉，可以放心地从事极易感染上艾滋病毒的活动。上面例子中的那位男子，决不是不知道感染艾滋病毒的风险，因为他自愿地接种了疫苗，受到长达一年的观察。但接种疫苗本身并没有使他停止有感染艾滋病毒风险的行为。他也许正是因为知道自己有艾滋病疫苗的保护，觉得不会被感染才敢于冒险。

可见，疫苗在艾滋病防治方面决不是万能的。在宣传艾滋病疫苗的时候，我们也要让公众了解它的局限性。预防艾滋病不能靠使用艾滋病疫苗，而要从改变人的吸毒和乱伦行为入手。要改变人的行为，就必须改变人的心。圣经说，“因为他心怎样思量，他为人就是怎样（箴言23：7）。”愿您情愿把自己的心交给神去改变，生活在他的祝福里。

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By Junhui Bian, Ph.D.

On March 12, 2005, the human trial of the first AIDS vaccine designed by a team of Chinese scientists formally began.  Eight volunteers participated in the Stage I of the Phase I trial.  Since the preliminary results are satisfactory, the Stage II trial opened on the 14^th of May, involving six volunteers.  The mass media all over China reported and celebrated the new hope in its potential to prevent the spread of human immunodeficiency virus (HIV).

At the end of 2004, there were nearly one million people infected with HIV in China.  More than 80,000 of them have developed acquired immunodeficiency syndrome (AIDS).  The AIDS epidemic has accelerated in major metropolitan areas in China.  Amid this extremely serious situation, the public are overly optimistic on the potential of this AIDS vaccine.  This is understandable.  However, as a scientist who had taken part in HIV research, I want to caution the public on the negative effects of AIDS vaccine.

There are two ways for the human body to gain immunity against an infectious disease.  First, one can get immunity by having the disease.  For example, after having measles once, one would not get measles again because he developed the antibodies and memory lymphocytes specifically against the measles virus.  Second, one can obtain immunity by vaccination.  Take the example of measles again:  A part of the measles virus, its protein or DNA, may be used as a vaccine to give to a healthy person.  He will also produce the antibodies and memory lymphocytes specifically against this part of measles virus in an immune response, much like the immune response against the whole virus.  When he is challenged by the real measles virus in an epidemic, this immunity prevents him from having measles.

The vaccine being tested in current human trial was made by recombining HIV and pox genes.  This is because the immune response induced by the HIV genes alone is not robust enough.  The HIV DNA used in this vaccine was isolated and modified from the current HIV strain spreading in Guangxi province.  This vaccine can only stay effective when the DNA of this natural HIV strain never mutates in the course of the epidemic.  Otherwise, the antibodies and memory lymphocytes induced by the vaccine could not recognize and destroy the natural HIV strain responsible for the epidemic.  Unfortunately, HIV viruses mutate their DNA very frequently, enabling the viruses to develop resistance against the effects of the vaccine.  There have been more than thirty AIDS vaccines in clinical trials since 1987.  And for this reason, none could be chosen.

I have once witnessed the extraordinary mutation rate in HIV.  When working in Oklahoma Medical Research Foundation, I placed a therapeutic gene in human T lymphocytes first.  Then, I added HIV to these cells to see if HIV could infect them and multiply in them.  The inhibition of this therapeutic gene on HIV replication lasted only seven days.  Thereafter, HIV began multiplying as usual in these human cells.  Here, facing the inhibitory factors, HIV kept altering its gene or DNA sequences until a resistant strain emerged.

Moreover, a report published in Proceedings of the National Academy of Sciences U. S. A. on March 22, 2005 (PNAS 102: 4512-4517, 2005) showed that a person, who received the same type of AIDS vaccine, was infected with HIV even under ideal conditions when he had robust vaccine-induced immune responses and the HIV DNA was not mutated.  This man was HIV-negative and he received a vaccine made of HIV and pox genes.  In the following year, he was monitored closely and the tests showed expected vaccine-induced responses.  Not only high titer antibodies, but also T lymphocytes and memory lymphocytes specifically against HIV were detected in this volunteer.  But two and half years after receiving the AIDS vaccine, this man became HIV-positive after one homosexual sex act.  Immediately, he also became a subject in a study conducted by the scientists in the Laboratory of Immunology, National Institute of Health, U. S. A.,  Dr. Michael Betts and his colleagues discovered that the vaccine-induced immune responses in this man were still intact.  In addition, the virus that infected him has the same HIV DNA as the vaccine and is the virus strain that the vaccine was designed to prevent.  More surprisingly, the vaccine not only didn’t prevent the HIV infection, but also greatly accelerated the AIDS progression in this man.  In the light of this experimental evidence, the researchers questioned the feasibility of AIDS vaccine-led prevention programs.

The negative effects of AIDS vaccines are not just limited to individuals and may have impacts on society as well.  The public trust vaccines a great deal in general because the vaccines for preventing other diseases are nearly one hundred percent effective.  In contrast, AIDS vaccines are much worse even in ideal situations.  Professor Xiaofang Yu, leading the clinical trial for the AIDS vaccine, admitted that the vaccine would be considered successful even if it achieves a rate of thirty percent in preventing AIDS.  This is far from the perceived effectiveness that the public have.  My worry is that many people will think that if AIDS vaccines are now about to be available and they will engage more in the behaviors highly risky for HIV infections.  The man in the example above definitely knew the risk of HIV infection since he even volunteered to receive the AIDS vaccine earlier and had been monitored closely for a year.  However, receiving the AIDS vaccine in itself did not stop him from engaging in the risky behavior that led to his infection.  Perhaps, he took the risk precisely because he thought that he was protected by the vaccine and would not be infected.

Thus, the vaccines are not panacea in AIDS prevention.  When publicizing AIDS vaccines, we must also let the public know their limitations.  To prevent AIDS, one can not rely on AIDS vaccines.  Instead, one must change the behaviors such as drug abuse and promiscuity.  To change one’s behavior, one must change his heart.  The bible says, “As a person thinks in his heart, so he behaves…(Proverbs 23:7).”  May you turn your heart to God, be changed by HIM and live in His rich blessings.