Bello, who tore the anterior cruciate ligament in his right knee in Argentina's runaway win over Australia in Santa Fe last Saturday, drops out of the 32-man squad for the Rugby Championship clash against the Springboks in Santiago del Estero on September 21.
Argentina coach Felipe Contepomi added two props as cover with a call-up for Lucio Sordoni, 26, and the 28-year-old Ignacio Calles, who ruptured his Achilles tendon in preparation for last year's World Cup but has since returned to action for his French club Pau.
Sordoni recently left Glasgow Warriors and has since signed for Racing 92 in France.
Veteran winger Matias Moroni returns from a hip injury that saw him miss the last two clashes against the Wallabies in the Rugby Championship while lock Pedro Rubiolo, who went off concussed in the opening minute of the 20-19 loss to the Wallabies in La Plata a fortnight ago, is also back.
Scrum-half Lautaro Bazan Velez, who suffered a muscle strain in the warm-up before the match in La Plata, is now also fit to play.
Argentina are the only team who can catch leaders South Africa in the Rugby Championship standings but must win the test in Santiago del Estero to keep up their hopes.
The two will then meet again in Nelspruit on September 28 but Argentina will announce the squad for that match after next Saturday's home test, the union said.
Argentinas squad:
Backs: Tomas Albornoz, Lautaro Bazan Velez, Gonzalo Bertranou, Mateo Carreras, Santiago Carreras, Santiago Chocobares, Lucio Cinti, Bautista Delguy, Gonzalo Garcia, Rodrigo Isgro, Juan Cruz Mallia, Ignacio Mendy, Matias Moroni, Matias Orlando, Justo Piccardo
Forwards: Bautista Bernasconi, Ignacio Calles, Pedro Delgado, Thomas Gallo, Juan Martin Gonzalez, Santiago Grondona, Marcos Kremer, Tomas Lavanini, Pablo Matera, Franco Molina, Julian Montoya, Joaquin Oviedo, Guido Petti, Pedro Rubiolo, Ignacio Ruiz, Joel Sclavi, Lucio Sordoni.
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