gettext does not translate when called in ajax

When loading content in gettext calls (__(), _e(), etc.) they translate fine when I render the page in the browser normally (PHP delivers the content to the browser), however when I make AJAX calls, the gettext does not translate.

I thought maybe it was that word specifically, but when I use the gettext call in content that is loaded from the server normally (not through ajax) it translates.
I’m using WPML, but I don’t think that has anything to do with it?

Is there anything special I have to do or add the load_plugin_textdomain function call to a specific action hook?

It’s added to the “plugins_loaded” action right now.
I use WordPress ajax methods as described in their docs and I get all the data, just don’t get gettext translations.

As advised here are snippets of the code that has the problem. I did not incldue the gettext .pot and .mo files, as I know those work (bc/ other text in there gets translated in the rest of the plugin itself). I just state what their name is and where they reside relevant to the plugin root.

//gettext files
// languages/my-plugin-fr_FR.pot
// languages/my-plugin-fr_FR.mo

//Javascript files
// js/main.js
(function($){

  function getResources() {
        $.ajax({
            type: "POST",
            url: ajax_object.ajaxurl,
            dataType: "json",
            data: {                    
                action: 'get_resources'               
            }
        })
        .done(function(data) {
            if (typeof data == "object" && data.hasOwnProperty("html")) {               
                $(".my-selector").empty().html(data.html);
            } else {
               alert("error on server");              
            }
        })
        .fail(function() {
            alert("error on server");  
        });
    }

  $(document).ready(function() {
     getResources();
  });

})(jQuery);
// end js/main.js


<?php
//MyPlugin class

class MyPlugin {    
  /// This value will be used as a unique identifier for translations
  public static $theme_domain_name = 'my-plugin';

  public function init() {
     if (!is_admin()) {         
      //any scripts and styles needed for the plugin to work in the front end
      add_action( 'wp_enqueue_scripts', array($this,'add_scripts_styles') );     
    }

    add_action('wp_ajax_get_resources', array($this,'ajax_get_resources'));
    add_action('wp_ajax_nopriv_get_resources', array($this,'ajax_get_resources'));
  }

  public function ajax_get_resources() {        
        $html = "";

        //just an example of returning post objects
        $posts = get_posts();

        $html .= $this->get_resources_html($posts);

        echo json_encode(array('html'=>$html));

        die();
  }

  public function add_scripts_styles() {
     wp_register_script('main-js', plugin_dir_url(__FILE__) . 'js/main.js', array('jquery'), '20131023' );
     wp_enqueue_script('main-js' );
     wp_localize_script('main-js', 'ajax_object', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) ) );
  }

  public function get_resources_html($resources) {
     $load_more_text = __('Load more',MyPlugin::$theme_domain_name);       

     //$html .= < do some other work on the resource posts provided >

     $html .= <<<LOAD
<a href="#">
    <span class="text-wrapper"><span class="text">
    {$load_more_text}
    </span></span>
</a>
LOAD;

    return $html;
  }
}
?>

<?php
//root plugin file my-plugin.php

require_once dirname( __FILE__ ) .'/MyPlugin.php';

$MyPlugin = new MyPlugin();    

add_action("plugins_loaded",function() {
    load_plugin_textdomain(MyPlugin::$theme_domain_name , false, dirname( plugin_basename(__FILE__) ) . '/languages/');
});

$MyPlugin->init();
?>