Abstract
Porcine circovirus associated diseases (PCVAD) caused by porcine circovirus type-2 (PCV-2) are emerging viral diseases with unfavourable effects on animal health and swine economy. We have a lot of information regarding the changes in the lymphoid organs and spleen in PCV-2 infected pigs whereas the reason for anaemic changes in the carcasses and the pathological effects of PCV-2 in bone marrow are still not well studied. Hence, an extensive study to identify the changes in myeloid and erythroid cells of bone marrow in PCV-2 infected pigs was carried out. Myeloid and erythroid series of cells were counted and analysed from the freshly collected bone marrow cytological smears from the PCV-2 suspected samples. Later, PCV-2 infection was confirmed by polymerase chain reaction (PCR) and characteristic histopathological findings. The PCR yielded an amplicon of ~ 481 bp product and those positive cases were selected for determining the Myeloid to Erythroid ratio (M : E ratio). However, values did not significantly differ in any of the cellular components between PCV-2 positive animals and PCV-2 negative animals which indicated that the bone marrow was not the specific target organ for PCV-2 viral infections. However, increased lympho-histiocytic and plasmacytic infiltration was noticed in both lymphoid and non-lymphoid organs. These characteristic features of PCV-2 infection could be considered as a major reason for increased proliferation of myeloid cells.
Highlights
Porcine circovirus associated diseases (PCVAD) caused by porcine circovirus type-2 (PCV-2) are emerging viral diseases with unfavourable effects on animal health and swine economy
PCV-2 infection was first reported thirty years back in Canada. Later it has been reported globally in association with many disease manifestations. They are PCV2-systemic disease (PCV-2-SD), PCV-2reproductive disease (PCV-2-RD) and porcine dermatitis and nephropathy syndrome (PDNS), which are recognised as porcine circovirus diseases (PCVD) or porcine circovirusassociated diseases (PCVAD) (Segalés, 2012; Correa-Fiz et al, 2020)
39 samples were processed for the detection of PCV-2 by polymerase chain reaction (PCR), among them seven were positive for PCV-2 (Fig.1)
Summary
Porcine circovirus associated diseases (PCVAD) caused by porcine circovirus type-2 (PCV-2) are emerging viral diseases with unfavourable effects on animal health and swine economy. An extensive study to identify the changes in myeloid and erythroid cells of bone marrow in PCV-2 infected pigs was carried out. Increased lympho-histiocytic and plasmacytic infiltration was noticed in both lymphoid and non-lymphoid organs These characteristic features of PCV-2 infection could be considered as a major reason for increased proliferation of myeloid cells. PCV-2 infection was first reported thirty years back in Canada Later it has been reported globally in association with many disease manifestations. Alteration in the cytology of myeloid and erythroid progenitor cells usually happens in viral infections. Detection of these changes could help in management of the disease as well as its prevention and control. This study can improve our current understanding of the effects of PCV-2 on bone marrow of pigs
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