How to use Include in query expression with object initilazation using EF 4.1

Question

I'm using Entity framework 4.1 code first and Here is a simplified version of my domain classes:

public class Tour
{
    public string TourName { get; set; }
    public virtual List<Event> Events { get; set; } 
}
public class Event
{
    public string EventName { get; set; }
    public virtual List<Participant> Participants { get; set; } 
}

public class Participant
{
    public string ParticipantName { get; set; }
}

and in the client application I use these classes:

public class EventItem
{
    public string DisplayName { get; set; }
    public IEnumerable<ParticipantItem> Tourists { get; set; } 
}

public class ParticipantItem
{
    public string Name { get; set; }
}

and the query:

var query = from tour in context.Tours
                    from evt in tr.Events
                    where tour.ApiKey == APIKey
                    select new EventItem
                               {
                                   DisplayName = evt.EventName,
                                   Tourists = from person in evt.Participants
                                              select new ParticipantItem
                                                         {
                                                             Name = person.ParticipantName
                                                         }
                               };


        return query.ToList();

It works with the exception that the inner query expression returns no data ( from person in evt.Participants...). I think it has something to do with lazy loading of Participants property of the Event object. But how to use "Include" in this query if that is the issue?