When the Beatles first appeared on “The Ed Sullivan Show” in 1964, they literally rocked the nation. Forty-five years later, Beatlemania still rages — and no one knows that better than the Fab Four Live, the Beatles tribute band that plays nightly at the V Theater at Planet Hollywood in Las Vegas.

While the anticipated launch of a Beatles video game and the re-release of the band’s entire music catalog certainly helped rekindle fan fervor, the secret to the Beatles’ lasting legacy is the music itself, says Glen McCallum, who plays the part of the Beatles’ lead guitarist George Harrison.

“If you don’t have great songs, no one’s going to be listening to you in 40 years,” he says. “The Beatles just played with such passion and such purity of soul — that’s what makes them timeless. And they’re all very likable characters, as well.”

The Fab Four Live show follows the original band’s short but legendary career, from their first U.S. television appearance on “The Ed Sullivan Show” through the “Sergeant Pepper” era, to the final rooftop concert held on top of the Apple Records studio building in 1969. The four band members — who have an uncanny resemblance to the original musicians — sing and play every note live.

The band has three costume changes to mark each of the main Beatles eras, including the iconic military-inspired outfits from the Sergeant Pepper’s Lonely Hearts Club Band album cover. The mood for each time period is slightly different, but the band keeps the tone lively throughout the show, McCallum says.

“They were four guys from Liverpool just arrived in the United States, and so they were totally excited and exuberant,” he says. “It was a whirlwind time for them. So I just try to get into that head space every night when the curtain opens.”

When McCallum left his native Australia for the United States eight years ago, he started out playing in a 1960s-themed musical revue. Naturally, the show had a Beatles segment, which is where he cut his teeth playing George Harrison.

“It was a lucky strike, I guess, because I just kind of fit the character,” he says. “Of any of the Beatles, that’s the character I would fit best.”

McCallum went on to play George in the “Legends in Concert” tribute performers show in Las Vegas before joining the Fab Four Live. His current bandmates — Steve Craig (John Lennon), Tony Felicetta (Ringo Starr), and John Hepburn (Paul McCartney) — also performed in other Beatles acts before they began playing together last year.

To get into character, McCallum studied video footage of the Beatles’ performances as well as television interviews with George Harrison.

“George, and all the other Beatles as well, felt no need to try to show off with any individual, technical flamboyance or brilliance,” he says. “They all sang and played from the heart and just for the total sound. That’s the kind of musician I am, and playing Beatles music and listening to it reinforces that importance for me.”

Fab Four Live plays hit Beatles tunes, including “I Want to Hold Your Hand,” “Hard Day’s Night,” “Twist and Shout,” “Yellow Submarine” and “Hey, Jude.”

McCallum admits it’s difficult to choose a favorite, but he does enjoy performing Harrison’s famous contribution to The White Album, “While My Guitar Gently Weeps.”

“That’s a fun song for me because I get to stretch out a bit on the guitar,” he says. “And I love the harmonies. The three-part harmonies in all of their stuff are very much a joy to sing, and that was a signature of their sound.”

Growing up, McCallum was aware of the Beatles thanks to his parents, who had the group’s later albums, including Let It Be, in their record collection. As McCallum became a more serious musician, he developed an “infinite respect” for the band.

“It’s just an amazing phenomenon,” he says. “I find it hard to put into words what they did in such a short time musically. So it’s kind of an honor to portray one of them and to play their music.”

Fab Four Live is always adding new elements to the show to keep it fresh for audience members, whether or not they are Beatles fans. For McCallum, success is giving the audience a sincere performance.

“That’s really important for me, that they feel what we do, not just see and hear — that it gave them a feeling inside that we meant it,” he says.