Mongoose: find and select only the fields specified in a virtual

I have a UserSchema schema in mongoose:

var UserSchema = new Schema({
  name: String,
  username: String,
  email: String,
  role: {type: String, default: 'user'},
  following: [{type: Schema.ObjectId, ref: 'User'}],
  followers: [{type: Schema.ObjectId, ref: 'User'}],
  hashedPassword: String,
  provider: String,
  salt: String,
  facebook: {},
  twitter: {},
  github: {},
  google: {}
});

I've created a virtual profile which returns only the information for the public profile:

UserSchema
  .virtual('profile')
  .get(function() {
    return {
      'username': this.username,
      'name': this.name,
      'role': this.role
    };
  });

My problem is how to get only this information when I'm making a find request. Here's my code:

UserSchema.statics = {
  list: function (options, callback) {
    var criteria = options.criteria || {};

    this.find(criteria)
      .select(/* What to put here? */)
      .limit(options.perPage)
      .skip(options.perPage * options.page)
      .exec(callback);
  } 
};

Of course, I can simply put there username, name and role but in that case I'd have code repetition. Can I avoid that?