This study aimed to evaluate the classical and atypical forms of ovine pulmonary adenocarcinomas (OPA) by immunohistochemical and molecular methods. OPA forms were compared among themselves in terms of proliferating cell nuclear antigen (PCNA), p53 tumour suppressor gene, carcinoembryonic antigen (CEA) and vascular endothelial growth factor-A (VEGF-A) expressions. Avidin–biotin–peroxidase method was used for immunohistochemistry. Half of the cases were classified as classical form and other six were determined to be atypical form. All of the OPA forms had positive reactions for PCNA, p53, CEA and VEGF-A immunoreactivity. However, immunohistochemical and statistical analyses indicated no significant difference between the classical and atypical forms of OPA. In addition, Jaagsiekte sheep retrovirus nucleic acid detection was investigated using reverse transcription polymerase chain reaction (RT-PCR). Nucleic acids from paraffinated tissue blocks were isolated using a phenol/chloroform based method.  Reverse transcription and polymerase chain reaction was performed using 2X One-step RT-PCR kit (Hibrigen, Türkiye, Catalogue Number: MG-OSPM-01). Five of the paraffin-embedded tissue samples (5/12) tested positive. Positive amplicons were sequenced and sequence data revealed that all isolates were type 2 exogenous Jaagsiekte sheep retrovirus (exJSRV), and positive samples contained minor amino acid changes among themselves. In conclusion, immunohistochemical parameters revealed the absence of significant difference between atypical and classical OPAs in terms of cancer dynamics, such as proliferation index, metastasis, angiogenesis capacity, and escape from apoptosis, and molecular methods also supported these findings.

To Cite This Article: Karakurt E, Coşkun N, Keleş ÖF, Beytut E, Yaman T, Yıldız Uysal A, Güneş S, Çiçek HA, 2025.Comparison of classical and atypical forms of ovine pulmonary adenocarcinomas using immunohistochemical andmolecular techniques. Pak Vet J. http://dx.doi.org/10.29261/pakvetj/2025.278