>perl -wMstrict -le
"my @strs = qw(
   <MIR-1><EXP-V-3><VACCVIRUS-PROP-1>
   <MIR-1><ASSC-PHRASE-1><VACCVIRUS-PROP-1><PATTERN-1>
   <MIR-1><EXP-V-0><ART-0><VACCVIRUS-PROP-1>
   <MIR-1><EXP-V-0><ART-0><BE-V><VACCVIRUS-PROP-1>
   <MIR-1><EXP-V-0><EXP-N-0><VACCVIRUS-PROP-1>
   );
 ;;
 my $tail = qr{ \d+ > }xms;
 ;;
 my $mir      = qr{ < MIR-            $tail }xms;
 my $exp_v    = qr{ < EXP-V-          $tail }xms;
 my $exp_n    = qr{ < EXP-N-          $tail }xms;
 my $assc_phr = qr{ < ASSC-PHRASE-    $tail }xms;
 my $vaccvir  = qr{ < VACCVIRUS-PROP- $tail }xms;
 ;;
 for my $str (@strs) {
   print qq{'$str'} if $str =~
     m{ \A
        $mir
        (?: $exp_v (?! $exp_n) | $assc_phr )
        .*?
        $vaccvir
      }xms;
   }
"
'<MIR-1><EXP-V-3><VACCVIRUS-PROP-1>'
'<MIR-1><ASSC-PHRASE-1><VACCVIRUS-PROP-1><PATTERN-1>'
'<MIR-1><EXP-V-0><ART-0><VACCVIRUS-PROP-1>'
'<MIR-1><EXP-V-0><ART-0><BE-V><VACCVIRUS-PROP-1>'