Identification of lactate dehydrogenase-elevating virus as the etiological agent of genetically restricted, age-dependent polioencephalomyelitis of mice

Five hybridomas that secrete monoclonal antibodies which neutralize the infectivity of lactate dehydrogenase-elevating virus (LDV) were isolated from BALB/c mice primed with Formalin-inactivated LDV. Competition analyses indicated that all five neutralizing monoclonal antibodies recognize contiguous, if not identical, epitopes on the envelope glycoprotein of LDV (VP-3) which are not recognized by nonneutralizing VP-3-specific monoclonal antibodies isolated from the same fusion. Despite the presence of neutralizing activity, polyclonal anti-LDV antibodies obtained from persistently infected mice did not compete for binding to LDV with four of the five neutralizing monoclonal antibodies tested. The results indicate that the envelope glycoprotein of LDV possesses a major neutralizing epitope which is poorly recognized, if at all, by mice during a natural infection but is rendered immunogenic by Formalin inactivation of the virus. The epitope was also not immunogenic in a rabbit, since its polyclonal LDV-neutralizing antibodies did not inhibit binding of the mouse monoclonal antibodies to LDV. Passive immunization with the neutralizing monoclonal antibodies did not protect mice from LDV infection and did not alter the course of infection. Neutralizing monoclonal antibodies have been used to select a neutralization escape variant by a novel combination of in vitro and in vivo isolation.

Section: Resultsmentioning

confidence: 95%

Formalin inactivation of the lactate dehydrogenase-elevating virus reveals a major neutralizing epitope not recognized during natural infection

Harty

Plagemann

1988

“…Because LDV infection of macrophages could be enhanced by complex formation of the virus with antiviral immunoglobulin antibody, the Fc receptors on the cells can be alternative receptors for LDV (4,14). While in MuLV-infected cells the infectivity of neurovirulent LDV-C was the highest among several isolates, in macrophages this difference was not observed (16,20). This result suggests that the mode of LDV infection of MuLV-infected cells is different from that of macrophages (16).…”

mentioning

confidence: 93%

“…So far, no significant difference in the capacity of replication in the peripheral organs as well as in the cultured macrophages has been noted among these strains. It is possible that the difference in virulency is due to the capacity of replication in the central nervous system (5,20,22,23), though the differences in the immunogenicity among various LDV isolates and in the antiviral immune response may affect the neurovirulency (30). The isolation of a variant which has lost its virulency after repeated passages of neurovirulent LDV in BALB/c mice without significant effect on the replication in the peripheral organs (22) may indicate that the ability to replicate in the central nervous of 104 (for cells) and 103 (for macrophages) ID50 per cell or transfected with RNA from each virus.…”

mentioning

confidence: 99%

Comparison of the ability of lactate dehydrogenase-elevating virus and its virion RNA to infect murine leukemia virus-infected or -uninfected cell lines

Inada

Kikuchi

Yamazaki

1993

Lactate dehydrogenase-elevating virus (LDV) has a strict species specificity. Cells or cell lines other than a particular subset of mouse primary macrophages which can support LDV replication in vitro have not been identified. LDV induces neurological disorders in old C58 or AKR strains, in which the involvement of multiple copies of the endogenous N-tropic murine leukemia virus (MuLV) genome and the Fv-1 locus of the mouse has been implicated. Our previous studies have demonstrated that LDV could infect and replicate in cell lines of the mouse or other species in vitro when they were infected with MuLV. The significance of and the precise mechanism underlying this phenomenon, however, remain unclear. We demonstrated in this study the efficient infection and replication of the virus in vitro by inoculation of its RNA mixed with liposome. No significant difference either in the efficiency of RNA transfection or in the ability to support its replication was observed among the various species' cell lines examined. In addition, by RNA transfection the virus replicated with equal efficiency in MuLV-infected and -uninfected cells or in macrophages derived from mice irrespective of their age. In contrast, the pattern of the infection by virus particles was quite different; LDV replication was observed only in macrophages (particularly from newborn mice) and MuLV-infected cells. By using various LDV isolates, it was demonstrated that the capability of replication between neurovirulent, LDV type C, and the other avirulent strains was almost the same in mouse cell lines when their RNA was introduced into the cells. Higher infectivity of LDV-C to MuLV-infected cells may be due to its efficient incorporation of the particles into MuLV-infected cells.

“…During repeated passages through C58/M mice, the tumor cells apparently became contaminated with LDV of unknown origin as a passenger virus. LDV-Ib (25) and LDV-C (22,30) were independently isolated from the spleens of Ib-cell-inoculated moribund C58/M mice. LDV-v was isolated in this laboratory from the spinal cord of a paralyzed C58/M mouse that had been inoculated with LDV-Ib (30).…”

Section: Methodsmentioning

confidence: 99%

Coexistence in lactate dehydrogenase-elevating virus pools of variants that differ in neuropathogenicity and ability to establish a persistent infection

Chen

Rowland

Anderson

et al. 1997

Neuropathogenic isolates of lactate dehydrogenase-elevating virus (LDV) differ from nonneuropathogenic isolates in their unique ability to infect anterior horn neurons of immunosuppressed C58 and AKR mice and cause paralytic disease (age-dependent poliomyelitis [ADPM]). However, we and others have found that neuropathogenic LDVs fail to retain their neuropathogenicity during persistent infections of both ADPMsusceptible and nonsusceptible mice. On the basis of a segment in open reading frame 2 that differs about 60% between the neuropathogenic LDV-C and the nonneuropathogenic LDV-P, we have developed a reverse transcription-PCR assay that distinguishes between the genomes of the two LDVs and detects as little as 10 50% infectious doses (ID 50) of LDV. With this assay, we found that LDV-P and LDV-C coexist in most available pools of LDV-C and LDV-P. For example, various plasma pools of 10 9.5 ID 50 of LDV-C/ml contained about 10 5 ID 50 of LDV-P/ml. Injection of such an LDV-C pool into mice of various strains resulted in the rapid displacement in the circulation of LDV-C by LDV-P as the predominant LDV, but LDV-C also persisted in the mice at a low level along with LDV-P. We have freed LDV-C of LDV-P by endpoint dilution (LDV-C-EPD). LDV-C-EPD infected mice as efficiently as did LDV-P, but its level of viremia during the persistent phase was only 1/10,000 that observed for LDV-P. LDV-permissive macrophages accumulated and supported the efficient replication of superinfecting LDV-P. Therefore, although neuropathogenic LDVs possess the unique ability to infect anterior horn neurons of ADPM-susceptible mice, they exhibit a reduced ability to establish a persistent infection in peripheral tissues of mice regardless of the strain. The specific suppression of LDV-C replication in persistently infected mice is probably due in part to a more efficient neutralization of LDV-C than LDV-P by antibodies to the primary envelope glycoprotein, VP-3P. Both neuropathogenicity and the higher sensitivity to antibody neutralization correlated with the absence of two of three N-linked polylactosaminoglycan chains on the ca. 30-amino-acid ectodomain of VP-3P, which seems to carry the neutralization epitope(s) and forms part of the virus receptor attachment site.