# open blast file
open (BLASTFILE, $blastfile) or die "Cannot open BLAST file\n";
# open header file
open (HEADERFILE, $headerfile) or die "Cannot open header file\n";
# open output file
open(OUTPUT, ">$outfile");

my $ender = "Query=";
my @headerline = <HEADERFILE>;
my $headerline = join ( '', @headerline);

while (my $blastline = <BLASTFILE> ) {
	my $blastcut = substr $blastline, 7;
	if ($headerline =~ /\Q$blastcut\E/) {
	print $blastcut;
	print until ( ($_ = <BLASTFILE>) =~ /$ender/i);
	}
	}
exit;