COX-2 expression following cells infection with the P. gingivalis strain without a polymorphic variant obtained from a donor with advanced PD (G231N, E232T, N235D- adv) was significantly reduced in comparison with its expression due to infection with the G231N, E232T, N235D+ adv P. gingivalis strain (p < 0.01) and infection with the ATCC T2 P. gingivalis strain (p < 0.001) (Figure 3C). The gene discussed is PTGS2; the disease is infection.