There's no need to use regex for most of that, since you aren't searching case insensitive anyway.
use strict;
use warnings;
my ($features, $count, @seq);
while (<DATA>) {
if (index($_, 'FEATURES') != -1) {
($features) = m/\s(\S+)/;
}
elsif (index($_, 'COUNT') != -1) {
($count) = m/\s(\d+)/;
}
elsif (index($_, 'ORIGIN') != -1) {
push @seq, $_ until index($_ = <DATA>, '//') != -1;
}
}
print "$features\n$count\n",@seq;
__DATA__
# extract of file:
#===============
FEATURES Location/Qualifiers
/note="blah blah"
COUNT 200
ORIGIN
1 lots of nice info
61 lots of nice info
121 lots of nice info
//