Multiplex fluorescent immunoassay for detection of mice infected with lactate dehydrogenase elevating virus.
(49/87)
Commercially available diagnostic tools for the detection of lactate dehydrogenase elevating virus (LDV) infection have been restricted to measurement of serum lactate dehydrogenase (LDH) activity levels and detection of the viral genome by RT-PCR assays. Serologic diagnosis of LDV infection has not been widely adopted due to the belief that the formation of antigen-antibody complexes and B-cell polyclonal activation may confound interpretation of results. In the current study, we inoculated BALB/c, C57BL/6, and Swiss Webster mice with LDV to compare the diagnostic reliability of a commercially available multiplex fluorescent immunoassay for the detection of antiLDV antibodies with that of the LDH enzyme assay. The serologic assay was vastly more sensitive and specific than was the LDH enzyme assay. Moreover, the serologic assay detected antiviral antibodies throughout the 3-mo time course of this study. These results suggest that antigen-antibody complex formation and polyclonal B-cell activation had little effect on assay performance. (+info)
Differential responses of disease-resistant and disease-susceptible primate macrophages and myeloid dendritic cells to simian hemorrhagic fever virus infection.
(50/87)
Pathogenesis of porcine reproductive and respiratory syndrome virus infection in gnotobiotic pigs.
(51/87)
The pathogenesis of porcine reproductive and respiratory syndrome virus (PRRSV) was determined in gnotobiotic pigs by studying the sequential development of microscopic lesions and sites of virus distribution and replication. Thirty-two pigs (three pigs/infected group and one pig/control group) were inoculated by nasal instillation of either PRRSV isolate ATCC VR-2332 (total dose 10(2.6) TCID50) or uninfected cell culture supernatant. Infected and control pigs were euthanized at 12 hours, and 1, 2, 3, 5, 7, 14, and 21 days postexposure (PE). Gnotobiotic pigs experimentally infected with PRRSV were viremic by 12 hours PE and subsequently developed pneumonia, lymphadenopathy, vasculitis, myocarditis and encephalitis. Lung lesions developed by day 3 PE, persisted through day 21 PE and were characterized by alveolar septa thickened by macrophages, alveolar proteinaceous and karyorrhectic debris, alveolar syncytial cells, and multifocal type II pneumocyte hypertrophy. Lymph node lesions varied in distribution and severity and were characterized by germinal center hypertrophy and hyperplasia, lymphocyte necrosis, multiple cystic spaces, and polykaryocytes within the cystic spaces. Heart lesions were a late feature of infection and all infected pigs had heart lesions on day 21 PE characterized by subendocardial, myocardial, and perivascular foci of lymphocytes. Vasculitis also varied in distribution and severity and affected all sizes of vessels. Results of this experiment indicate that PRRSV is a multisystem disease characterized initially by viremia with subsequent virus distribution and replication in multiple organs causing interstitial pneumonia, vasculitis, lymphadenopathy, myocarditis, and encephalitis. (+info)
Cytotoxic T cells are elicited during acute infection of mice with lactate dehydrogenase-elevating virus but disappear during the chronic phase of infection.
(52/87)
Lactate dehydrogenase-elevating virus (LDV) invariably establishes a life-long viremic infection in mice, which is maintained by replication of LDV in a renewable subpopulation of macrophages and escape from all host immune responses. We now demonstrate that cytotoxic T lymphocytes (CTLs) that specifically lyse LDV-infected macrophages and 3T3 cells producing the nucleocapsid protein of LDV were elicited in Swiss, B10.A, and (Swiss x B10.A)F1 mice. To detect target cell lysis, splenocytes needed to be expanded by a 5-day in vitro culture in the presence of recombinant interleukin 2 and syngeneic LDV protein-expressing cells. In vitro culture resulted in the specific expansion of CD8+ cells which mediated the lysis of target cells in a major histocompatibility complex class I-restricted manner. When CTLs were added to macrophage cultures at 1 h after infection with LDV, the lysis of the infected macrophages by the CTLs started about 5 h postinfection (p.i.) and, at an effector cell/target cell ratio of 25:1, resulted in the lysis of all LDV-infected macrophages in a culture by about 7 h p.i. However, lysis of the LDV replication in a culture was not rapid enough to significantly suppress the LDV yield in the culture. LDV replication in mice was also little affected by the presence of CTLs which were induced by immunization with 3T3 cells expressing the LDV nucleocapsid protein. Furthermore, all CTL precursor cells in infected mice had disappeared by 30 days p.i. Loss of CTL precursor cells in infected mice probably reflected high-dose clonal exhaustion, since LDV infection of a mouse results in massive production of LDV in all tissues of the mouse, but especially in lymphoidal tissues, and accumulation of LDV in newly formed germinal centers. Furthermore, slow LDV replication continues in the thymus and other lymphoidal organs. (+info)
Production, characterization and reactivity of monoclonal antibodies to porcine reproductive and respiratory syndrome virus.
(53/87)
This report describes the preparation of six monoclonal antibodies (MAbs) raised against a British isolate of porcine reproductive and respiratory syndrome virus (PRRSV), their characterization in terms of protein specificity and their reactivity with different PRRS viruses from Europe and the USA. Radioimmunoprecipitation and Western blotting studies of MAb reactivity with proteins from cell lysates of infected cells and purified virus revealed that four of the six MAbs (WBE1 and WBE4-6) precipitated a 15 kDa viral protein. Further studies using in vitro translated products of the Lelystad virus genome showed that this protein was the product of ORF7, the putative nucleocapsid protein. The specificity of another MAb, WBE2, was found to be for a 45 kDa protein, determined to be the product of ORF3 and demonstrated to be present in purified virion preparations. The protein specificity of the sixth MAb, WBE3 could not be determined. Thirty-three PRRSV isolates from Europe and the USA were grown in alveolar macrophages and examined by immunoperoxidase staining, using the panel of six MAbs. All European isolates were recognized by the four MAbs specific for the putative nucleocapsid, but the viruses showed different patterns of reactivity with WBE2 and WBE3. Furthermore, these two MAbs stained only a small proportion of the cells infected with certain isolates, suggesting that a single isolate may be antigenically heterogeneous. No MAbs bound to US isolates, indicating a consistent antigenic difference between the putative nucleocapsid of US and European isolates. Detergent extraction of cell lysate antigen abrogated the binding of WBE1-3, suggesting that the epitopes are conformation dependent. (+info)
Interleukin-12 gene expression after viral infection in the mouse.
(54/87)
Interleukin-12 is a lymphokine that triggers gamma interferon secretion by various cells and differentiation of T-helper lymphocytes towards the Th1 subtype. Since viruses are potent inducers of gamma interferon production and elicit immune responses most probably mediated by Th1 cells, like B-cell immunoglobulin G2a secretion, we analyzed interleukin-12 message expression after infection of mice with lactate dehydrogenase-elevating virus, mouse hepatitis virus, and mouse adenovirus. Our results indicated that the message for the p40 component of interleukin-12 was transiently increased shortly after infection. Interleukin-12 was expressed mainly by macrophages. Therefore, production of interleukin-12 might constitute the initial event that would determine the subsequent characteristics of the immune response elicited by viral infections. (+info)
Lactate dehydrogenase-elevating virus entry into the central nervous system and replication in anterior horn neurons.
(55/87)
The initial replication of lactate dehydrogenase-elevating virus (LDV) in mice, its invasion of the central nervous system (CNS) and infection of anterior horn neurons in C58 and AKXD-16 mice were investigated by Northern and in situ hybridization analyses. Upon intraperitoneal injection, LDV replication in cells in the peritoneum was maximal at 8 h post-infection (p.i.). Next, LDV infection was detected in bone marrow cells and then in macrophage-rich regions of all tissues investigated (12 to 24 h p.i.). By 2 to 3 days p.i., LDV RNA-containing cells had largely disappeared from all non-neuronal tissues due to the cytocidal nature of the LDV infection of macrophages. In the CNS at 24 h p.i. LDV replication was very limited and confined to cells in the leptomeninges. LDV replication in the cells of the leptomeninges should result in the release of progeny LDV into the cerebrospinal fluid and thus its dissemination throughout the CNS. However, in C58 and AKXD-16 mice, which are susceptible to paralytic LDV infection, only little LDV RNA and few LDV-infected cells were detectable in the spinal cord until at least 10 days p.i. Extensive cytocidal infection of anterior horn neurons occurred only shortly before the development of paralytic symptoms between 2 and 3 weeks p.i. The reason for the relatively long delay in LDV infection of anterior horn neurons is not known. No LDV RNA or LDV RNA-containing cells were detected in the brain, except in the leptomeninges at early times after infection. (+info)
Reduced streptozotocin-induced insulitis in CD-1 mice by treatment with anti-intercellular adhesion molecule-1 and anti-lymphocyte function associated antigen-1 monoclonal antibodies together with lactic dehydrogenase virus infection.
(56/87)
Multiple low-dose streptozotocin (SZ)-induced insulitis is an animal model for insulin-dependent diabetes mellitus characterized by a mononuclear cell infiltration. SZ-induced insulitis and blood glucose concentrations were reduced by treatment with anti-intercellular adhesion molecule-1(ICAM-1) and anti-lymphocyte function associated antigen-1 (LFA-1) monoclonal antibodies. This suppressing effect was also seen in mice infected with lactic dehydrogenase virus (LDV). These results suggest that the expression of ICAM-1 in islets and LFA-1 on mononuclear cells may be important in the development of SZ-induced insulitis. The suppressive effect of LDV infection on the development of insulitis is discussed. (+info)