[OS X TeX] Missing accented vowels

[Vittorio]

Experienced as a FreeBSD teTeX user and an absolute beginner with the  
package mactex under macosx  in TeXShop (unicode utf-8 in preferences)  
I have a document with the following preamble:

\documentclass[11pt,a4paper]{article}
\usepackage[italian]{babel}

\usepackage{currvita}
\newcommand*{\ac}[1]{\mbox{#1}}
\tolerance=600
\pagestyle{empty}
\begin{document}
........................


in which I see the accented vowels of the Italian language. But after  
compilation with pdflatex the accented letters disappeared.

What should I do to make them reappear?

Vittorio