Human Anti-Parvovirus B19 NS1 Monoclonal antibody, clone 2535

Human parvovirus B19 has been associated with various cases of kidney injuries with different glomerular phenotypes. In immunocompromised individuals, insufficient production of neutralizing antibodies can lead to chronic PVB19 carriage and manifestations. However, PVB19 DNA has been detected in bone marrow and peripheral blood for months or years in seemingly immunocompetent individuals, despite the presence of neutralizing antibodies. We report here PVB19-induced recurrent anuric acute kidney failures in a 57-year-old man over a 7-year period with persistent PVB19 infection and then PVB19-associated cryoglobulinemia. Acute renal failures were preceded by influenza-like syndrome associated with arthralgia, skin rash, and low-grade fever. Serum, bone marrow, renal, and digestive PVB19 replication was found in the different episodes. Endocapillary proliferative glomerulonephritis evolved into membranoproliferative glomerulonephritis. Complete renal recovery occurred after each bout. Off-label subcutaneous immunoglobulin therapy resulted in disappearance of blood and bone marrow PVB19 viral load and stopped the glomerulonephritis recurrence. Subcutaneous immunoglobulin therapy withdrawal resulted in renal relapse with cryoglobulin-associated manifestations.

Canine parvovirus (CPV) non-structural protein-1 (NS1) plays crucial roles in CPV replication and transcription, as well as pathogenic effects to the host. However, the mechanism was not fully understood. Lack of NS1 antibody is one of the restricting factors for NS1 function investigation. To prepare NS1 monoclonal antibody (mAb), the NS1 epitope (AA461 similar to AA650) gene was amplified by PCR, and inserted into pGEX-4T-1vector to construct the prokaryotic expression vector of GST-tag-fused NS1 epitope gene. The NS1 fusion protein was expressed in E. coli, and purified with GSH-magnetic beads, and then used to immunize BALB/c mice. The mouse splenic lymphocytes were isolated and fused with myeloma cells (SP 2/0) to generate hybridoma cells. After several rounds of screening by ELISA, a hybridoma cell clone (1B8) stably expressing NS1 mAb was developed. A large amount of NS1 mAb was prepared from mouse ascites fluid. The isotype of NS1 mAb was identified as IgG1, which can specifically bind NS1 protein in either CPV-infected cells or NS1 vector-transfected cells, indicating the NS1 mAb is effective in detecting NS1 protein. Meanwhile, we used the NS1 mAb to investigate NS1 dynamic changes by qRT-PCR and location by confocal imaging in CPV-infected host cells and showed that NS1 began to appear in the cells at 12 h after CPV infection and reached the highest level at 42 h, NS1 protein was mainly located in nucleus of the cells. This study provided a necessary condition for further investigation on molecular mechanism of NS1 function and pathogenicity.