#include <boost/serialization/base_object.hpp>

class B 
{
public:
    virtual ~B() {}
    template<class Archive>
    void serialize(Archive& ar, unsigned int version)
    {
        ar & i;
    }
    int i;
};

class D : public B {
public:
    template<class Archive>
    void serialize(Archive& ar, unsigned int)
    {
        ar & boost::serialization::base_object<B>(*this);
    }
};