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PORCINE CIRCOVIRUS-2 IMPACT ON THEMORPHOLOGICAL SIGHT OF PIG LYMPH NODESInga Pigiņka, Edīte BirģeleTable 4The structural changes of lymph nodes (scores) mainly with severe amount of PCV2 in lymph nodesThe name oflymph nodeValued parametersNumber of the animalNo. 3No. 7No. 9No. 10No. 15Mean indexof parameterlnn. inguinalessuperf. sinisterlnn. inguinalessuperf. dexterlnn. mesentericicranialelnn.tracheobronchalesamount of PCV2 antigen + +++ +++ +++ +++ +++visualization of the follicle structure 2 3 3 3 3 2.80decrease amount of lymphocytes 1 2 3 3 2 2.20increase amount of histiocytes 1 2 3 2 2 2.00amount of PCV2 antigen + +++ +++ +++ +++ +++visualization of the follicle structure 2 3 3 3 3 2.80decrease amount of lymphocytes 1 2 3 3 2 2.20increase amount of histiocytes 1 2 3 2 2 2.00amount of PCV2 antigen +++ +++ +++ +++ +++ +++visualization of the follicle structure 3 3 3 3 3 3.00decrease amount of lymphocytes 3 3 3 3 2 2.80increase amount of histiocytes 3 3 2 2 2 2.40amount of PCV2 antigen ++ ++ +++ ++ +++ +++visualization of the follicle structure 3 3 3 3 3 3.00decrease amount of lymphocytes 3 3 3 3 3 3.00increase amount of histiocytes 3 3 2 2 3 2.60score 2.00 – 2.75) compared to other investigatedparameters of lymph nodes.Also, lymphocytes depletion in lymph nodes ofthese animals was relatively severe, score from 1.75to 2.25; like the increase amount of histiocytes – from1.50 to 1.75 (Table 3).In the Table 4 are shown the lymph nodes structuralchanges of piglets in whose lymph nodes mainlysevere amount (+++) of PCV2 antigen was observed.It is observed, that generally in lymph nodesof animals in this group, all investigated structuralparameters had greatly changed: visualization of thefollicle structure was scored in the range from 2.80 to3.00; the amount of lymphocytes was decreased andamount of histiocytes was increased – on the averagefrom 2.00 to 3.00 scores (Table 4).By analyzing lymph nodes group individually foreach animal, it should be noted that one piglet (No. 3)had different morphological changes in lnn. inguinalessuperficiales. These changes were relatively smaller(scores 1-2), that could be associated with the mildamount of PCV2 antigen in them. Presumably PCV2was not distributed throughout the whole organismof piglet No. 3 yet, as it was observed in other fouranimals of this group.Summarizing data about all structural parameterchanges in lymph nodes, it has been concluded thatPCV2 was relatively more affected in the follicle oflymph nodes. Follicles lose their typical structure,and presumably also are affected by B lymphocytepopulation, because it is known that lymphocytes Bconcentrate directly in the follicles of lymph nodes(Willard-Mack, 2006).The amount of lymphocytes decreasedsimultaneously with the PCV2 antigen increase inthem. The question – which population of lymphocytes– T or B – decreased in lymph node, will be clarified inthe further stage of research.If the amount of PCV2 antigen in lymph nodesincreases, then the amount of histiocytes increasesaccordingly. It is thought that main target cells forPCV2 replication are the monocytes and macrophages(Rosell et al., 1999). Then macrophages ’get old’ andare overtaken by histiocytes (Willard-Mack, 2006). Itis likely that ‘fight’ between macrophages and virushas been for a long time. It is possible that those pigscould have disorder of humoral immunity (Allan etal., 1999; Bolin et al., 2001; Krakowka et al., 2001).To understand changes of individual structuralparameters of lymph nodes with different amountof PCV2 antigen better, structural changes of lymphnodes were compared with prevailing amount of thevirus antigen in lymph nodes (Table 5).Comparing the histological structure of lymphnodes with mild (+) amount of PCV2 antigen andthe structure of lymph nodes without presence ofPCV2 antigen (0), it is observed that all investigatedparameters have significant difference in structuralchanges in all lymph nodes. In all investigatedparameters, there is a significant difference instructural changes in all lymph nodes with mild andsevere amount of PCV2 antigen (Table 5).206 Research for Rural Development 2012