Histopathological, serological, molecular and electron microscopy detection of Maedi-Visna infection in sheep population in the West of Iran.

BACKGROUND: Maedi-Visna (MV) is a progressive lymphoproliferative viral disease that affects multiple organs of small ruminants, including sheep and goats. The disease occurs primarily in the lung tissue and causes interstitial pneumonia. AIMS: The aim of present study was to investigate the prevalence of ovine MV infection in Iranian sheep population through macroscopic, histopathological, serological, and molecular assays, as well as transmission electron microscopy (TEM). METHODS: Lung and blood samples of one-hundred female sheep (≤ 2 years old) referred to the Kermanshah slaughterhouse with respiratory symptoms were collected for histopathological and molecular evaluations. Corresponding serum samples were also collected for serological examination. RESULTS: Histopathological study showed the Maedi-like pulmonary lesions in 85% of the affected lungs, which included the interstitial pneumonia, smooth muscle hypertrophy of alveolar septa and around the blood vessels, interstitial lymphoplasmacytic infiltration and lymphofollicular hyperplasia. Specific antibodies against MV virus were detected in 7% of serum samples. Long terminal repeat (LTR) region of MV provirus was amplified in three (3%) DNA samples, extracted from the suspected lungs. Sequencing analysis of polymerase chain reaction (PCR)-positive samples confirmed the presence of MV provirus in the genome. No amplification was observed, neither in the DNA samples extracted from the blood samples of suspected sheep nor the control group. Transmission electron microscopy also confirmed the presence of MV virions inside the cytoplasmic membrane of MV-infected macrophages. CONCLUSION: Although histopathology can provide a preliminary estimation of Maedi in populations, definitive diagnosis of the disease needs to be approved by more sensitive techniques such as serological examinations and molecular analysis.

Histopathological study and F1L gene sequence analysis of contagious ecthyma in small ruminants of Shiraz suburb, Iran.

Contagious ecthyma, also known as Orf, is a common viral skin disease of sheep and goats caused by a Parapoxvirus. This research was conducted with the aims of histopathological study and genetic analysis of Orf virus with PCR technique based on F1L gene in 50 sheep and goats suspicious of contagious ecthyma in affected areas of Shiraz suburb. All 50 contagious ecthyma-like tissue samples were maintained in 10% buffered formalin, embedded in paraffin, sectioned into 5µm slices and dyed with hematoxylin-eosine. The histopathological examination showed 100% positivity. Epidermal hyperplasia with prominent rete ridges, hydropic degeneration of the necrotic keratinocytes, eosinophilic intracytoplasmic inclusion bodies in vacuolated cells and subcorneal pustules were the main hallmarks of this disease. For molecular analysis, after DNA extraction, all samples were amplified by PCR method and the outcome demonstrated positivity in 25 specimens (50%). Of these, 10 definitely positive specimens were analyzed for nucleotide sequencing. Thus, a strain named Orf-059-Shiraz was recorded in the GeneBank and subsequently underwent phylogenetic analysis. The outcome of the molecular study approved half of the positive ecthyma specimens in histopathological method. Furthermore, phylogenetic analysis based on 059 gene showed that this gene is highly conserved. Utilization of histopathology and clinical signs can assist with rapid and low-cost diagnosis of infectious ecthyma whereas PCR is able to dissociate from similar diseases among clinical samples of endemic regions.

Histopathological study and F1L gene sequence analysis of contagious ecthyma in small ruminants of Shiraz suburb, Iran

Contagious ecthyma, also known as Orf, is a common viral skin disease of sheep and goats caused by a Parapoxvirus. This research was conducted with the aims of histopathological study and genetic analysis of Orf virus with PCR technique based on F1L gene in 50 sheep and goats suspicious of contagious ecthyma in affected areas of Shiraz suburb. All 50 contagious ecthyma-like tissue samples were maintained in 10% buffered formalin, embedded in paraffin, sectioned into 5μm slices and dyed with hematoxylin-eosine. The histopathological examination showed 100% positivity. Epidermal hyperplasia with prominent rete ridges, hydropic degeneration of the necrotic keratinocytes, eosinophilic intracytoplasmic inclusion bodies in vacuolated cells and subcorneal pustules were the main hallmarks of this disease. For molecular analysis, after DNA extraction, all samples were amplified by PCR method and the outcome demonstrated positivity in 25 specimens (50%). Of these, 10 definitely positive specimens were analyzed for nucleotide sequencing. Thus, a strain named Orf-059-Shiraz was recorded in the GeneBank and subsequently underwent phylogenetic analysis. The outcome of the molecular study approved half of the positive ecthyma specimens in histopathological method. Furthermore, phylogenetic analysis based on 059 gene showed that this gene is highly conserved. Utilization of histopathology and clinical signs can assist with rapid and low-cost diagnosis of infectious ecthyma whereas PCR is able to dissociate from similar diseases among clinical samples of endemic regions.