show php string containing comma in tag-it input field

I am using https://github.com/aehlke/tag-it plugin in php page.

Now the problem is, i have a set of string like

$str1="AlaqahdariDeh-eShu, Afghanistan";
$str2="`Ohonua, Tonga";
$str3="India";
$str=$str1.",".$str2.",".$str3;

which i want to show in tag-it input field like this

<input type="text" id="branchText" name="branchText" value="<?php echo $str;?>" class="ui-widget" size="20" style="display: none;">

but tag-it also splitting the $str1 in two value like this

Can anyone suggest to show $str1 and $str2 as a two string instead four string in tag-it input field?