Establishment of a new bovine leukosis virus producing cell line

Detection of the BLV provirus from nasal secretion and saliva samples using BLV-CoCoMo-qPCR-2: Comparison with blood samples from the same cattle

Bovine leukemia virus (BLV) induces enzootic bovine leukosis, which is the most common neoplastic disease in cattle. Sero-epidemiological studies show that BLV infection occurs worldwide. Direct contact between infected and uninfected cattle is thought to be one of the risk factors for BLV transmission. Contact transmission occurs via a mixture of natural sources, blood, and exudates. To confirm that BLV provirus is detectable in these samples, matched blood, nasal secretion, and saliva samples were collected from 50 cattle, and genomic DNA was extracted. BLV-CoCoMo-qPCR-2, an assay developed for the highly sensitive detection of BLV, was then used to measure the proviral load in blood (n=50), nasal secretions (n=48), and saliva (n=47) samples. The results showed that 35 blood samples, 14 nasal secretion samples, and 6 saliva samples were positive for the BLV provirus. Matched blood samples from cattle that were positive for the BLV provirus (either in nasal secretion or saliva samples) were also positive in their blood. The proviral load in the positive blood samples was >14,000 (copies/1×10(5) cells). Thus, even though the proviral load in the nasal secretion and saliva samples was much lower (<380 copies/1×10(5) cells) than that in the peripheral blood, prolonged direct contact between infected and healthy cattle may be considered as a risk factor for BLV transmission.

Antibodies to the core proteins of Nairobi sheep disease virus/Ganjam virus reveal details of the distribution of the proteins in infected cells and tissues

Nairobi sheep disease virus (NSDV; also called Ganjam virus in India) is a bunyavirus of the genus Nairovirus. It causes a haemorrhagic gastroenteritis in sheep and goats with mortality up to 90%. The virus is closely related to the human pathogen Crimean-Congo haemorrhagic fever virus (CCHFV). Little is currently known about the biology of NSDV. We have generated specific antibodies against the virus nucleocapsid protein (N) and polymerase (L) and used these to characterise NSDV in infected cells and to study its distribution during infection in a natural host. Due to its large size and the presence of a papain-like protease (the OTU-like domain) it has been suggested that the L protein of nairoviruses undergoes an autoproteolytic cleavage into polymerase and one or more accessory proteins. Specific antibodies which recognise either the N-terminus or the C-terminus of the NSDV L protein showed no evidence of L protein cleavage in NSDV-infected cells. Using the specific anti-N and anti-L antibodies, it was found that these viral proteins do not fully colocalise in infected cells; the N protein accumulated near the Golgi at early stages of infection while the L protein was distributed throughout the cytoplasm, further supporting the multifunctional nature of the L protein. These antibodies also allowed us to gain information about the organs and cell types targeted by the virus in vivo. We could detect NSDV in cryosections prepared from various tissues collected post-mortem from experimentally inoculated animals; the virus was found in the mucosal lining of the small and large intestine, in the lungs, and in mesenteric lymph nodes (MLN), where NSDV appeared to target monocytes and/or macrophages.

Design of NK-2-derived peptides with improved activity against equine sarcoid cells

Equine sarcoid is a topically accessible model for the evaluation of anticancer peptides acting by physical membrane disruption avoiding the complexity of a systemic application. We aim at evaluating and improving natural peptides for host defence as lead structures, where we focus on the cationic and amphipathic peptide NK-2. Cytotoxicity tests, fluorescence microscopy and a chip-based biosensor, which enabled real-time monitoring of cell metabolism, were applied. Cancer cell killing was dynamic with an initial phase of increased cellular respiration, followed by membrane destruction. NK-2 was substantially improved and shortened. Novel peptides exhibited a fivefold improved activity against sarcoid cells, while haemolysis remained almost unaltered. Similar Zeta potential and similar amount of surface phosphatidylserine of sarcoid and normal skin cells are responsible for a lack of selectivity between these two cell types.

Peroxidase-linked assay for detection of antibodies against bovine leukosis virus

A peroxidase linked assay (PLA) was designed to screen bovine sera for the presence of specific antibodies against bovine leukosis virus (BLV). Out of 201 samples of bovine sera analyzed, 52.2% were considered positive by PLA, 26.4% by AGID, and 38.9% by ELISA. Western blotting analyses excluded 27 samples found to be positive by PLA. PLA showed 100% of sensitivity when compared with AGID and ELISA. Specificity was 64.8% and 78%, respectively (kappa coefficients were 0.70 and 0.83). These findings indicate that PLA can be used as an alternative method for the diagnosis of BLV infection in cattle.

Agar gel immunodiffusion analysis using baculovirus-expressed recombinant bovine leukemia virus envelope glycoprotein (gp51/gp30(T-))

Bovine leukemia virus (BLV) envelope glycoprotein (gp51/ gp30(T-)), consisting of BLV gp51 and BLV gp30 that lacked its C-terminal transmembrane domain, was expressed in insect cells under the control of the baculovirus polyhedron promoter. Recombinant BLV gp51/gp30(T-) secreted from insect cells was determined by immunofluorescence, enzyme-linked immunosorbent and western blot assays using a BLV-specific monoclonal antibody and BLV-positive bovine antibodies. An agar gel immunodiffusion (AGID) test using gp51/gp30(T-) as the antigen for the detection of BLV antibodies in serum was developed and compared to traditional AGID, which uses wild type BLV antigen derived from fetal lamb kidney cells. AGID with the recombinant BLV gp51/gp30(T-) was relatively more sensitive than traditional AGID. When the two methods were tested with bovine sera from the field, the recombinant BLV gp51/gp30(T-) and traditional antigen had a relative sensitivity of 69.8% and 67.4%, respectively, and a relative specificity of 93.3% and 92.3%. These results indicated that the recombinant BLV gp51/gp30(T-) is an effective alternative antigen for the diagnosis of BLV infection in cattle.