Changes Of Immune Function And TGF-β₁mRNA Expression In Local Mucosal Immune Tissues Of SPF Chicks Infected With IBDV

In this study, taking21-day-old SPF chicks as research, indirect enzymelinkedimmunosorbent assay（IELISA）, immunohistochemistry staining, acidic alpha naphthyl acetateesterase staining method（ANAE） and real-time fluorescence quantitative PCR were used todiscover the dynamic changes which the number of Igs producing cells and T lymphocytes, theexpression of TGF-β₁mRNA in local mucosal tissues——gland of Harder, cecal tonsils, Peyer’spatch of duodenum and ileum and the content of immunoglbbulin（Ig）A, IgM, IgG in localhumor——tear, trachea fluid, bile and intestinal fluid of SPF chicks infected with IBDV, whichfully revealed the changes in local mucosal tissues when SPF chicks infected with IBDV. Thisresults will provide a scientific basis for prevention and control of IBDV. The conclusion were asfollows:1) The content of IgA, IgM, IgG in tear, trachea fluid, bile and intestinal fluid and the numberof Igs producing cells in gland of Harder, cecal tonsils, Peyer’s patch of duodenum and ileum of21-day-old SPF chicks infected with IBDV were lower than control chicks in different degrees.The content of IgA, IgG in tears and IgA, IgM in bile of chicks infected with IBDV weresignificantly or extremely significantly lower than control chicks in3to7days after virusinfection （P<0.01or P<0.05）; the content of IgM in tears, IgG in bile and the above three intrachea fluid and intestinal fluid were obviously reduced in3to5days （P<0.01or P<0.05）. At thesame time, the number of IgA and IgM producing cells of gland of Harder, IgM and IgG producingcells of Peyer’s patch of duodenum were significantly or extremely significantly lower thancontrol chicks in5to14days after virus infection （P<0.01or P<0.05）; the number of IgGproducing cells in gland of Harder, IgA producing cells in Peyer’s patch of duodenum and theabove three Igs producing cells in cecal tonsils and Payer’patch of ileum of SPF chicks infectedwith IBDV were obviously reduced in5to7days （P<0.01or P<0.05）. These results indicated thatthe function of humoral immunity in respiratory and digestive tract mucosal of SPF chicks infectedwith IBDV were significantly restrained.2) The number of T lymphocytes in gland of Harder, cecal tonsils, Payer’s patch of duodenumand ileum of the21-day-old SPF chicks infected with IBDV were lower than control chicks to some certain degree. They all significantly or extremely significantly lower than the control chicksin5to14days after the SPF chicks infected with IBDV （P<0.01or P<0.05）. The results showedthat the function of cellular immunity in respiratory and digestive tract mucosal of SPF chicksinfected with IBDV were also inhibited to some extent.3) The expression of TGF-β₁mRNA in gland in Harder and cecal tonsils of21-day-old SPFchicks infected with IBDV were enhanced compared with control chicks in different degree. Theywere obviously increased in3to28days and3to14days （P<0.01），respectively. Both all reachedthe peak in7days after virus infection, and then gradually decline. These results indicated that theexpression of TGF-β₁was activated when the chicks infected with IBDV. The early immunefunction inhibition is closely related to the increased expression of TGF-β₁mRNA.