October 13, 1986

In the rarefied world of biotechnology, the Chiron Corporation has always had the respect of its peers. Now, it is also starting to bask in the limelight long enjoyed by such older and larger competitors as Genentech Inc. and the Cetus Corporation. This week, Chiron and Ciba-Geigy Ltd., the Swiss-based pharmaceutical giant, announced an ambitious joint venture to develop a series of genetically engineered vaccines for AIDS, herpes and malaria, among other diseases. And this summer, Chiron received the first Food and Drug Administration approval of such a vaccine for human use. The approval of the drug for hepatitis B, a potentially deadly liver disease, made the five-year-old company one of the few biotech enterprises with a product to sell.

John Cardinal O'Connor has publicly expressed concern that the support given by Catholic clergymen to the young man accused of killing Jennifer Dawn Levin could aggravate relations between Catholics and Jews. In an article in the weekly newspaper Catholic New York, in which no names were mentioned, Cardinal O'Connor wrote, ''I am worried that mercy toward a Catholic boy could be perceived as callousness toward a Jewish girl.'' At least two Catholic clergymen, including Archbishop Theodore E. McCarrick of Newark, have become involved in the case in which the suspect, Robert E. Chambers Jr., was released earlier this month on $150,000 bail despite a plea by the Levin family. Archbishop McCarrick, who has said he has known Mr. Chambers for years through his mother, wrote a letter in support of Mr. Chambers' character when bail was being considered.

President Reagan and his aides came here with the expectation that Moscow was prepared to reach tentative agreements on medium-range missiles and other arms issues without first solving the problem of space-based defenses. And they had reason to believe this, based on the two leaders' pledge last November in Geneva to seek an ''interim'' accord on medium-range weapons, and based on more recent public statements by Soviet leaders. But today in the dramatic finale to their two-day get-together, Mikhail S. Gorbachev told them they were wrong. To the Soviet leader, every agreement to reduce arms depended on American willingness essentially to scrap Mr. Reagan's dream for space-based defenses against missile attacks. And he had a basis for this belief as well. That same joint statement in Geneva pledged the two sides to ''accelerate'' efforts to ''prevent an arms race in space.''

A new generation of apartment buildings resembling the traditional, prewar structures of New York is being built in Manhattan, challenging the tall, thin apartment towers standing in plazas that have been typical of the last 25 years. Behind the growing popularity of these buildings in the last year is a rare convergence of opinion among architects, preservationists, neighborhood activists and planners in the Department of City Planning. After years of dismissing old neighborhoods, architects with a post-modernist interest in historical styles are now taking traditional buildings on old city blocks as architectural models. Preservationists see the new buildings - which typically have storefronts on the street and whose upper stories step back in a ''wedding cake'' design - as compatible with older structures and with the social fabric of established neighborhoods. ''But the new buildings are not just happening because architects think it's nice,'' said the director of the Manhattan office of the Department of City Planning, Con Howe.

The heads of the nation's biggest corporations are not yet persuaded that the United States has finally succeeded in reversing its huge deficit in international trade. Although some companies have begun to see a pickup in export orders, most chief executives remain highly doubtful that American business is yet efficient enough - or the dollar low enough - to regain lost shares of both foreign and domestic markets. ''I think it's too early to tell,'' said Henry H. Henley Jr., chairman of Cluett, Peabody & Company, the apparel maker. ''I can't see we've turned the corner yet.''