MBP and infection: Overall antibody response Generally, MBP-IgM titers were affected by housing (F(1.52) = 3.6, P < 0.05), infection (F(1.52) = 4.0, P < 0.10), sampling day (F(6.307) = 62.3, P < 0.001), and by the housing × sampling day (F(6.307) = 2.2), infection × sampling day (F(6.307) = 4.4), and housing × infection × sampling day (F(6.307) = 2.2) interactions (P < 0.05, see Figure 1C).