We produced a monoclonal antibody (MAb) (7G10) that has blocking activity against porcine reproductive and respiratory syndrome virus (PRRSV). In this study, we identified the components of the 7G10 MAb-bound complex as cytoskeletal filaments: vimentin, cytokeratin 8, cytokeratin 18, actin, and hair type II basic keratin. Vimentin bound to PRRSV nucleocapsid protein and anti-vimentin antibodies showed PRRSV-blocking activity. Vimentin was expressed on the surface of MARC-145, a PRRSV-susceptible cell line. Simian vimentin rendered BHK-21 and CRFK, nonsusceptible cell lines, susceptible to PRRSV infection. These results suggest that vimentin is part of the PRRSV receptor complex and that it plays an important role in PRRSV binding with the other cytoskeletal filaments that mediate transportation of the virus in the cytosol.

Hybridomas secreting monoclonal antibodies (MAbs) against the Nebraska calf diarrhea strain of bovine rotavirus (BRV) were characterized. Indirect fluorescent-antibody assay, immunodot assay, and immunoprecipitation were used to select hybridomas that produced anti-BRV MAbs. Seven of the MAbs were shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot assay to be reactive with the BRV outer capsid protein, VP7, which has a molecular mass of 37.5 kDa. None of the seven MAbs were reactive with canine rotavirus, bovine coronavirus, or uninfected Madin-Darby bovine kidney cells. Two clones, 8B4 (immunoglobulin G2a [IgG2a]) and 2B11 (IgG1), were found suitable for use in an antigen capture enzyme-linked immunosorbent assay for detecting BRV in bovine fecal samples. Both were subtype A specific (G6 subtype) but did not react with all isolates of BRV group A.Rotavirus, a member of the Reoviridae family, is an important cause of gastroenteritis in young children, calves, monkeys, chickens, pigs, sheep, and horses (1,14). It is nonenveloped and has double-shelled capsids surrounding a genome of 11 double-stranded RNA segments. Seven serological groups of rotavirus, A to G, have been identified, but only groups A, B, C, D, and G have been characterized well (15). Each group can be differentiated by polyacrylamide gel electrophoretic mobilities (2, 23).Among the seven serogroups, group A rotavirus has been studied in greatest detail, and it is the serogroup most commonly found in cattle worldwide. The virus is composed of a core surrounded by VP6, the major inner capsid protein. The outer capsid layers of infectious bovine rotavirus (BRV) particles contain two proteins, VP4 and VP7. The VP4 (P) types are spike protein encoded by RNA segment 4 (19, 21). They constitute important outer capsid proteins with various functions such as hemagglutinating activity (22) and neutralization activity (10,25,37), and when cleaved by trypsin into VP5 and VP8, they enhance the infectivity of the virus. There is evidence that rotavirus VP4 sequences are diverse (32). Using monoclonal antibodies (MAbs) against VP4, diversity has been shown in the amino acid sequences of epitopes that are critical for cross-reaction and neutralization of rotaviruses (18,19,22,33). Both VP4 and VP7 are associated with stimulation of serotype-specific antibodies and in vivo protection. Serotypes 1 to 4 of VP7 are glycosylated (6). Proteins other than VP4 and VP7, such as VP6, associated with stimulation of serotypespecific antibodies, may participate in protection against BRV infection; however, neutralizing antibodies in vitro have been shown to be specific against VP4 and VP7. Protection against rotavirus infection appears to rely mainly on stimulation of neutralizing antibodies against the outer capsid proteins, VP4 and VP7 (27).Many established protocols and commercial kits are available to detect rotavirus infection for human diagnostic medical applications including electron microscopy and enzyme-linked immunosorbent assay (E...