- Mice coinfected with T. spiralis or H. polygyrus and with mouse Norovirus (MNV) had increased viral loads and reduced amounts of specific CD4+ T cells expressing IFN-γ and TNF-alpha when compared to the mice infected with Norovirus alone- Conclusion: Parasite infection alters the immune response creating favorable environment for the parasite at the expense of antiviral immunity. The gene discussed is IFNG; the disease is infection.