The virtues of "Teresa the Thief," a new Italian comedy at the K-B Janus, seem magnified in the wake of American comedies as starved for wit and social vision as "Lost and Found" and "The Main Event."

A satiric chronicle of nearly 50 years in the precarious existence of an impoverished, hard-luck yet tenacious heroine, "Teresa the Thief" is animated by a comic spirit at once uninhibited and expansive. And the movie keeps the fun in a vivid, sardonic social perspective.

This feat once seemed like second nature to specialists in American movie comedy, and one can discern Woody Allen, Albert Brooks and Richard Pryor striving to resurrect it in their current starring vehicles. It's an approach one has come to expect from the Italian screenwriting team Age-Scarpelli, who also collaborated on "The Pizza Triangle" and "We All Loved Each Other So Much."

"Teresa" reunites at least four key collaborators from "The Pizza Triangle." In addition to Age-Scarpelli (Agenore Incrocci and Furio Scarpelli), the new film draws on the abundant talents of Monica Vitti, a poignant embodiment of feminine susceptibility and fortitude over four decades of maddening, recurrent hard knocks, and Carlo Di Palma, who makes an impressive showing as a director after a distinguished career as a cinematographer.

Teresa narrates the story of her unenviable life, which begins in 1919 when she is born into a poor, over-crowded farm family dominated by a short-tempered father. Teresa's mother dies suddenly when the girl is still in her teens. Shortly before losing his wife, Teresa's father had curtly dismissed the thought that she might be coming down with something. "I'll never let a doctor in this house!" he roars. "We're healthy people!" Viewing her mother's corpse, Teresa reflects, "It was the first time I'd ever seen her lying down, looking quiet and peaceful."

Teresa quickly alienates herself from the new domestic regime, which finds her father sharing his bed with a pair of horse-faced sisters-in-law. Discovered trying to spook her aunts by pretending to be the disapproving ghost of her mother, Teresa is literally thrown out of the house by her easily enraged dad. Running away from home as fast as her legs can take her, Teresa expresses an ironic elation: "There I was without a roof over my head. I felt so free!"

The joy is brief. It is Teresa's comic fate to jump from the frying pan into the fire. Every time she seems to get a break, good fortune quickly backfires. All her silver linings are shattered by humiliating, disillusioning reversals. Having escaped from home, she ends up slaving in the household of a station master, whose son has impregnated her before going off to fight for the greater glory of II Duce. Returning shortly before she gives birth to their son, the pompous young warrior cautions her not to expect much: "Teresa, you've had your moment of happiness. Live with that moment."

Teresa ends up marrying this unworthy flower of Fascist manhood when his father insists on it, for reasons that have nothing to do with the girl's predicament. Again, her happiness is short-lived. The newlyweds move to Rome, where the young husband lazes about in the society of petty criminals and then abandons his wife. With the outbreak of World War II, Teresa finds herself compelled to surrender her little boy to her husband's hated sisters back in the country while she endeavors to eke out a disreputable living in the city.

Teresa got into criminal partnership with two other young women. A bungled burglary soon lands all of them in prison and sets an incorrigible pattern for the remainder of Teresa's chronicle. She's in and out of jail, in and out of the loony bin. During the stretches of freedom, she supports herself through various forms of petty theft and suffers through several romantic misalliances, all the time hoping in vain to accumulate a nest egg and return to her child. Things never quite work out. As Teresa sums it up matter-of-factly, "We all have our unhappy moments, but mine go on and on."

The screenplay might be faulted for going on at slightly greater length than the conception warrants.

Despite the harrowing nature of Teresa's history, the film maintains a remarkable comic buoyancy. Often on the verge of despair, Teresa never quite gives up the ghost. Although the screenplay simmers with implicit social criticism, staging Teresa's vicissitudes against a backdrop of Italian decline, fall and dubious recovery, the filmmakers avoid sentimental breast-beating and soapbox propagandizing.

The basic idiom is gallows humor, expressed with a nutty originality. For example, there's a delightfully wacky episode in which Teresa and her pals, desperately hungry, kidnap a flamingo from the zoo and spend days trying to boil the scrawny bird into edibility.

Carlo Di Palma's credits as a cinematographer included "The Pizza Triangle" for Ettore Scola and "The Red Desert" and "Blow-Up" for Michelangelo Antonioni. One would expect him to be astute exploiting both the animated and melancholy aspects of Vitti's beauty and to reveal a sophisticated sense of composition. He exceeds these expectations. Vitti looks lovely, and the movie looks vigorously attractive, enlivened by a witty, playful sense of composition and atmosphere.

I was particularly fond of the setting and lighting scheme used to introduce the character of Tonino, one of the wastrels who abuses Teresa's love. He first appears at a dancehall gaily decorated with light bulbs strung in various patterns. A star pattern flickers on next to Tonino when Teresa notices him standing alone against a wall. It's a wonderful image, fusing the real, the symbolic, the comic.

Di Palma must also be responsible for the exceptionally dramatic use of a glaring reflection, bounced off the handbag of a woman riding in a street-car, which leads to the restoration of Teresa's morale in the concluding episode. A humorously contrived yet sincerely felt social comedy, "Teresa the Thief" insinuates itself as enjoyably and then suggestively as "We All Loved Each Other So Much," "Bread and Chocolate," "Get Out Your Handkerchiefs," "Femmes Fatales" and "The Toy." It's another good example of how serious intentions and comic expression can enhance one another on the screen. CAPTION: Picture 1, Monica Vitti in "Teresa the Thief"; Picture 2, Monica Vitti in "Teresa the Thief"