#! /usr/bin/perl

use strict;
use warnings;
use HTML::Entities;

my $str = "TEST&TEST;A&E&an&nbsp;HTML---&nbsp;string - &lt;&copy; TVS&gt;";
my $decoded = decode_entities($str);
my $encoded = encode_entities($decoded);

print $encoded;

__DATA__
TEST&amp;TEST;A&amp;E&amp;an&nbsp;HTML---&nbsp;string - &lt;&copy; TVS&gt;