Differential mechanisms of complement-mediated neutralization of the closely related paramyxoviruses simian virus 5 and mumps virus

Abstract

The complement system is an important component of the innate immune response to virus infection. The role of human complement pathways in the in vitro neutralization of three closely related paramyxoviruses, Simian Virus 5 (SV5), Mumps virus (MuV) and Human Parainfluenza virus type 2 (HPIV2) was investigated. Sera from ten donors showed high levels of neutralization against HPIV2 that was largely complement-independent, whereas nine of ten donor sera were found to neutralize SV5 and MuV only in the presence of active complement pathways. SV5 and MuV neutralization proceeded through the alternative pathway of the complement cascade. Electron microscopy studies and biochemical analyses showed that treatment of purified SV5 with human serum resulted in C3 deposition on virions and the formation of massive aggregates, but there was relatively little evidence of virion lysis. Treatment of MuV with human serum also resulted in C3 deposition on virions, however in contrast to SV5, MuV particles were lysed by serum complement and there was relatively little aggregation. Assays using serum depleted of complement factors showed that SV5 and MuV neutralization in vitro was absolutely dependent on complement factor C3, but was not dependent on downstream complement factors C5 or C8. Our results indicate that even though antibodies exist that recognize both SV5 and MuV, they are mostly non-neutralizing and viral inactivation in vitro occurs through the alternative pathway of complement. The implications of our work for development of paramyxovirus vectors and vaccines are discussed.

Virion-Associated Complement Regulator CD55 Is More Potent than CD46 in Mediating Resistance of Mumps Virus and Vesicular Stomatitis Virus to Neutralization

“…Although the micrographs were not quantitated, many virions appeared to be lysed, as evidenced by the loss of the bullet-shape morphology and release of nucleocapsid-like structures (arrows). Previous data indicate that this lysis does not occur with C3-deficient serum (16). There were very few intact virions evident by 30 min of treatment.…”

“…The Enders strain of MuV (ATCC VR-1379) and Orsay strain of VSV were grown in CHO cells supplemented with 2% heat-inactivated (HI) serum. Viruses were purified by sucrose gradient ultracentrifugation as described previously (16). Time-dependent virus neutralization by NHS was carried out as previously described (16), with remaining infectivity determined by plaque assay on CV-1 cells.…”

“…Electron microscopy (EM) analysis of sucrose gradient-purified MuV or VSV was carried as previously described (16). Briefly, the viruses were placed on carbon-coated 200-mesh gold grids (EM Sciences, PA) and incubated in a humidified chamber for 5 min, before blocking with a solution of 1% bovine serum albumin in PBS.…”

ThePlasmodium falciparumblood stages acquire factor H family proteins to evade destruction by human complement

“…4B). When the schizonts were cultured in HIS instead of NHS or when the NHS was inactivated by addition of 20 mM EDTA (Des Prez et al , 1975; Johnson et al , 2008), no TCC‐positive band was detected in the schizont‐iRBC lysates. TCC formation on the surfaces of schizont‐iRBCs, cultivated either in 20 vol% NHS or HIS for 1 h, was further quantified via ELISA.…”

“…A total number of 2 × 10 7 per 100 µl schizont‐iRBCs or purified MZ of strain F12 were incubated in cell culture medium containing 20 vol% NHS, NHS inactivated by 20 mM EDTA (Des Prez et al , 1975; Johnson et al , 2008) or HIS for 1 h at 37°C. For trypsin treatment, the cells were incubated in cell culture medium containing 100 µg ml −1 trypsin for 30 min at 37°C, followed by 5× washing with incomplete medium, prior to incubation with 20 vol% NHS.…”