Highly sensitive enhanced chemiluminescence immunodetection method for herpes simplex virus type 2 Western immunoblot

Realizing the promise of reverse phase protein arrays for clinical, translational, and basic research: a workshop report: the RPPA (Reverse Phase Protein Array) society

Reverse phase protein array (RPPA) technology introduced a miniaturized "antigen-down" or "dot-blot" immunoassay suitable for quantifying the relative, semi-quantitative or quantitative (if a well-accepted reference standard exists) abundance of total protein levels and post-translational modifications across a variety of biological samples including cultured cells, tissues, and body fluids. The recent evolution of RPPA combined with more sophisticated sample handling, optical detection, quality control, and better quality affinity reagents provides exquisite sensitivity and high sample throughput at a reasonable cost per sample. This facilitates large-scale multiplex analysis of multiple post-translational markers across samples from in vitro, preclinical, or clinical samples. The technical power of RPPA is stimulating the application and widespread adoption of RPPA methods within academic, clinical, and industrial research laboratories. Advances in RPPA technology now offer scientists the opportunity to quantify protein analytes with high precision, sensitivity, throughput, and robustness. As a result, adopters of RPPA technology have recognized critical success factors for useful and maximum exploitation of RPPA technologies, including the following: preservation and optimization of pre-analytical sample quality, application of validated high-affinity and specific antibody (or other protein affinity) detection reagents, dedicated informatics solutions to ensure accurate and robust quantification of protein analytes, and quality-assured procedures and data analysis workflows compatible with application within regulated clinical environments. In 2011, 2012, and 2013, the first three Global RPPA workshops were held in the United States, Europe, and Japan, respectively. These workshops provided an opportunity for RPPA laboratories, vendors, and users to share and discuss results, the latest technology platforms, best practices, and future challenges and opportunities. The outcomes of the workshops included a number of key opportunities to advance the RPPA field and provide added benefit to existing and future participants in the RPPA research community. The purpose of this report is to share and disseminate, as a community, current knowledge and future directions of the RPPA technology.

Comprehensive analysis of expression profile reveals the ubiquitous distribution of PPPDE peptidase domain 1, a Golgi apparatus component, and its implications in clinical cancer

PPPDE peptidase domain 1 (PPPDE1) is a recently identified gene; however, its expression regulation and biological function are unclear. Previous studies have indicated that PPPDE1 is involved in embryogenesis, apoptosis induction and cell cycle regulation. In the present study, we first used an anti-PPPDE1 antibody to determine that endogenous PPPDE1 is located in the Golgi apparatus. Immunohistochemistry (IHC) of mouse embryos indicated that PPPDE1 was markedly distributed in liver, skin, intestinal villi, and muscles, whereas Western blot analysis of mouse mature organs revealed its ubiquitous expression, without an appreciable distinction in protein abundance. Surprisingly, another potential isoform of PPPDE1 with a molecular weight of 18 kD (rather than its predicted molecular weight of 21 kD) was detected in the mouse kidney, testis, and intestine. Moreover, microarrays that were derived from twelve tumor types revealed that PPPDE1 expression was significantly lower in pancreas, stomach, and skin tumors compared with normal tissue from these organs. We specifically and extensively analyzed PPPDE1 expression in clinical samples and observed strong associations between PPPDE1 expression and (i) differentiation grade in pancreatic ductal adenocarcinoma and (ii) T stage in skin squamous cell carcinoma. Our data are the first to reveal the expression profile of PPPDE1 protein and its implications in cancer. These results will contribute to the understanding of the expression regulation and biological functions of PPPDE1 in development and carcinogenesis.

Reverse phase protein microarrays advance to use in clinical trials

Individualizing cancer therapy for molecular targeted inhibitors requires a new class of molecular profiling technology that can map the functional state of the cancer cell signal pathways containing the drug targets. Reverse phase protein microarrays (RPMA) are a technology platform designed for quantitative, multiplexed analysis of specific phosphorylated, cleaved, or total (phosphorylated and non-phosphorylated) forms of cellular proteins from a limited amount of sample. This class of microarray can be used to interrogate tissue samples, cells, serum, or body fluids. RPMA were previously a research tool; now this technology has graduated to use in research clinical trials with clinical grade sensitivity and precision. In this review we describe the application of RPMA for multiplexed signal pathway analysis in therapeutic monitoring, biomarker discovery, and evaluation of pharmaceutical targets, and conclude with a summary of the technical aspects of RPMA construction and analysis.

Cervical antibodies to herpes simplex virus proteins in pregnancy and puerperium: a pilot study

Objective: This study was undertaken to evaluate the changes in total and anti-herpes simplex virus (HSV)-specific cervical IgA and IgG antibody profiles during and after pregnancy.

Methods: Serum and cervical secretions were obtained from pregnant patients before 20 weeks gestation, at 34–36 weeks gestation, and at 6 weeks postpartum and tested for total IgA and IgG antibody and for IgA and IgG to HSV proteins by Western blot.

Results: Seven women were HSV seronegative, 14 HSV-1 seropositive, and 14 HSV-2 ± HSV-1 seropositive. Minimal changes in the serum anti-HSV profiles were seen over the 3 visits. The total cervical IgA, IgG, and protein levels did not change between the 2 pregnancy visits but tended to increase at the postpartum visit. No consistent change in cervical HSV-specific IgA and IgG was seen during pregnancy, but the levels increased markedly at the postpartum visit.

Conclusions: Lower cervical anti-HSV antibody levels may be related to the previously reported increased frequency of a reactivation of HSV during late pregnancy. Further evaluation is necessary to confirm and quantify the changes in genital immunity during pregnancy and to evaluate whether the increased levels at the postpartum visit are sustained.

Methodological considerations for improving Western blot analysis

The need for a technique that could allow the determination of antigen specificity of antisera led to the development of a method that allowed the production of a replica of proteins, which had been separated electrophoretically on polyacrylamide gels, on to a nitrocellulose membrane. This method was coined Western blotting and is very useful to study the presence, relative abundance, relative molecular mass, post-translational modification, and interaction of specific proteins. As a result it is utilized routinely in many fields of scientific research such as chemistry, biology and biomedical sciences. This review serves to touch on some of the methodological conditions that should be considered to improve Western blot analysis, particularly as a guide for graduate students but also scientists who wish to continue adapting this now fundamental research tool.

Novel cross-linked enzyme–antibody conjugates for Western blot and ELISA

Covalent cross-linking of enzymes to antibodies to produce immunoconjugates for Western blot analysis and ELISAs was achieved using in vacuo cross-linking methodology [Simons, B.L., King, M.C., Cyr, T., Hefford, M.A., Kaplan, H., 2002. Covalent cross-linking of proteins without chemical reagents. Protein Sci. 11, 1558.]. The advantageous feature of this methodology for producing enzyme-antibody conjugates is that the cross-linking is accomplished without the use of chemical modifying or activating reagents. This reduces the potential activity loss due to chemical modification and allows easy recovery of any free antibody or native enzyme. In vacuo cross-linking of horseradish peroxidase (HRP) to anti-rabbit immunoglobulin G (IgG) produced an enzyme-linked antibody with an improved sensitivity for antigen detection compared to a commercial conjugate prepared by conventional chemical cross-linking methods. A soluble multi-enzyme-based immunoconjugate was prepared by the in vacuo cross-linking of HRP to a high molecular weight polyglutamic acid polymer followed by the in vacuo cross-linking of a limiting amount of antibody to yield an antibody-(HRP)n-polyglutamate complex. This complex had a detection signal 100-fold greater than that of the 1:1 enzyme-antibody conjugates prepared by chemical cross-linking.

Characterization of a cDNA of Peroxiredoxin II Responding to Hydrogen Peroxide and Phagocytosis in Amoeba proteus

Phagocytic cells have defense systems against reactive oxygen species generated as the first non-specific defense mechanism against invading pathogens or microorganisms. We cloned a cDNA encoding a 21.69-kDa protein in Amoeba proteus homologous to 2-Cys peroxiredoxin (Prx-Ap). In the disk inhibition assay using H2O2 as an oxidizing agent, Escherichia coli overproducing Prx-Ap showed better viability than did E. coli transformed with pBluescript II SK for control. Monoclonal antibodies (mAb) produced against Prx-Ap reacted with a 22.5-kDa protein and several minor proteins. In Western blot analysis, levels of the 22.5-kDa protein in amoebae treated with 2-mM H2O2 for 1 h increased about 2-fold over those in control cells. Immunofluorescence scattered throughout the cytoplasm also increased after H2O2 treatment. In Northern blot analysis using the cDNA as a probe, the level of transcripts also changed with H2O2 treatment. When amoebae were fed with Tetrahymena, the intensity of immunofluorescence increased from 15 min and persisted until 2 h after phagocytosis. These results suggest that the 22.5-kDa protein of A. proteus is a Prx protein and that it has an antioxidant property responding to phagocytosis.

A population-based study of primary human herpesvirus 6 infection

BACKGROUND

Serologic studies indicate that human herpesvirus 6 (HHV-6) infects 90 percent of children by two years of age. Little is known about the acquisition, virologic course, and clinical manifestations of HHV-6 infection.

METHODS

We prospectively studied a cohort of 277 children from birth through the first two years of life to define the pattern of acquisition of HHV-6. The children's saliva was tested weekly for HHV-6 DNA with the use of the polymerase chain reaction. Parents maintained a daily log of signs and symptoms of illness in their children.

RESULTS

Primary HHV-6 infection occurred in 130 children, with cumulative percentages of 40 percent by the age of 12 months and 77 percent by the age of 24 months. The peak age of acquisition was between 9 and 21 months. The acquisition of HHV-6 was associated with female sex (adjusted hazard ratio, 1.7; 95 percent confidence interval, 1.2 to 2.4) and having older siblings (adjusted hazard ratio, 2.1; 95 percent confidence interval, 1.4 to 2.9). Among 81 children with a well-defined time of acquisition of HHV-6, 93 percent had symptoms, and 38 percent were seen by a physician. None had seizures. As compared with children who had other illnesses, those with primary HHV-6 infection were more likely to have fever (P=0.003), fussiness (P=0.02), diarrhea (P=0.03), rash (P=0.003), and roseola (P=0.002) and were more likely to visit a physician (P=0.003).

CONCLUSIONS

The acquisition of HHV-6 in infancy is usually symptomatic and often results in medical evaluation. Roseola occurs in a minority of patients, and febrile seizures are infrequently associated with primary HHV-6 infection. Older siblings appear to serve as a source of HHV-6 transmission.

Herpes simplex virus type-2 specific glycoprotein G-2 immunomagnetically captured from HEp-2 infected tissue culture extracts

Monoclonal antibody H1206 anti-HSV-2 gG-2 bound to tosylactivated paramagnetic Dynabeads (Dynal) has been used to isolate HSV-2 type-specific gG-2 from solubilized HEp-2 HSV-2 infected cell extracts. The immunomagnetically captured type-specific glycoprotein reacted strongly with monoclonal antibody H1206 and demonstrated a single band with apparent molecular weight of 100000 (100 kDa) and a doublet band with an apparent molecular weight of 60000-64000 (60-64 kDa). We observed the same exact banding pattern when monoclonal H1206 was immunoblotted with Helix pomatia lectin purified HSV-2 gG-2. The immunomagnetically purified gG-2 was unreactive to monoclonal antibody H1379 anti-HSV-1 gG-1 and four human HSV antibody negative sera. In addition, 20 human HSV antibody positive sera obtained from the Centers for Disease Control (CDC), Atlanta, GA, were used for the evaluation of our methodology. Immunoblotting of the human HSV antibody positive samples were in agreement with the CDC HSV serological designation. Sera characterized by reactivity to the immunomagnetically purified gG-2 in conjunction with Western blot has the potential to be used as a confirmatory serological test or to determine the accuracy of clinical serological immunoassays used to determine HSV-2 seropositivity.

NPDC-1, a novel regulator of neuronal proliferation, is degraded by the ubiquitin/proteasome system through a PEST degradation motif

Neural proliferation and differentiation control protein-1 (NPDC-1) is a protein expressed primarily in brain and lung and whose expression can be correlated with the regulation of cellular proliferation and differentiation. Embryonic differentiation in brain and lung has classically been linked to retinoid signaling, and we have recently characterized NPDC-1 as a regulator of retinoic acid-mediated events. Regulators of differentiation and development are themselves highly regulated and usually through multiple mechanisms. One such mechanism, protein degradation via the ubiquitin/proteasome degradation pathway, has been linked to the expression of a number of proteins involved in control of proliferation or differentiation, including cyclin D1 and E2F-1. The data presented here demonstrate that NPDC-1 is likewise degraded by the ubiquitin/proteasome system. MG-132, a proteasome inhibitor, stabilized the expression of NPDC-1 and allowed detection of ubiquitinated NPDC-1 in vivo. A PEST motif (rich in proline, glutamine, serine, and threonine) located in the carboxyl terminus of NPDC-1 was shown to target the protein for degradation. Deletion of the PEST motif increased NPDC-1 protein stability and NPDC-1 inhibitory effect on retinoic acid-mediated transcription. NPDC-1 was phosphorylated by several kinases, including extracellular signal-regulated kinase. Phosphorylation of NPDC-1 increased the in vitro rate of NPDC-1 ubiquitination. The MEK inhibitor, PD-98059, an inhibitor of extracellular signal-regulated activation, also inhibited the formation of ubiquitinated NPDC-1 in vivo. Together these results suggest that retinoic acid signaling can be modulated by the presence of NPDC-1 and that the protein level and activity of NPDC-1 can be regulated by phosphorylation-mediated proteasomal degradation.

Cervicovaginal neutralizing antibodies to herpes simplex virus (HSV) in women seropositive for HSV Types 1 and 2

Antibodies to herpes simplex virus type 1 (HSV-1) and HSV-2 of the immunoglobulin G (IgG) and IgA isotypes were detected in the cervicovaginal secretions (CVS) of 77 HSV-1- and HSV-2-seropositive but clinically asymptomatic African women by type-specific enhanced chemiluminescence Western blotting (ECL-WB). Of the 77 subjects, 34 were HIV negative, shedding HSV-2 DNA in their genital secretions; 20 were HIV positive, shedding HSV-2 DNA; and 23 were HIV negative, not shedding HSV-2 DNA. HSV-specific IgG was detected in CVS of nearly 70% of the women studied. HSV-specific IgA was found in CVS of 50% of the women studied. The distribution of CVS HSV-specific antibodies to each HSV type was highly heterogeneous, with a slight predominance of detectable IgG to HSV-1 (59%) over IgG to HSV-2 (41%), whereas the frequency of detectable IgA to HSV-1 (39%) was similar to that of IgA to HSV-2 (36%). The presence of detectable HSV-specific antibodies was inversely associated with HSV-2 DNA genital asymptomatic shedding but was not affected by HIV seropositivity. In addition, 13 of 77 (17%) CVS samples showed neutralizing activity against HSV-2, as assessed by an HSV-2 in vitro infectivity reduction assay. Neutralizing activity in CVS was associated with the presence of IgG and/or IgA antibodies to HSV-1 and/or to HSV-2 by ECL-WB. Among women whose CVS showed HSV-2-neutralizing activity, the specific activity of HSV-specific neutralizing antibodies was substantially (fivefold) higher in HSV-2 DNA shedders than in nonshedders. In conclusion, HSV-specific antibodies are frequently detected in CVS of asymptomatic African women seropositive for HSV-1 and HSV-2. A subset of these women had functional neutralizing activity against HSV-2 in their CVS. The origin of these antibodies and their role in HSV-2 disease of the female genital tract remain to be determined.

T cell immunity to herpes simplex viruses in seronegative subjects: silent infection or acquired immunity?

During the course of investigating T cell responses to HSV among volunteers entering trials of investigational genital herpes vaccines, 6 of the 24 immunocompetent subjects with no prior history of oral/labial or genital herpes possessed HSV-specific T cell immunity but, by multiple determinants of even the most sensitive serological assays, remained seronegative to HSV-1 and -2. Of these six immune seronegative (IS; HSV-seronegative with HSV-specific T cell responses) subjects, two had transient HSV-specific T cell responses, while four had CD4(+) and CD8(+) T cell responses directed at HSV that persisted for up to 4 years. CD4(+) T cell clones were isolated that recognized and had high binding affinities to epitopes in HSV-2 tegument proteins. All six IS subjects had potential sexual exposure to an HSV-2-infected sexual partner. Oral and genital mucosal secretions were sampled and tested for the presence of infectious HSV and HSV DNA. No evidence of HSV was detected in >1500 samples obtained from these IS subjects. The identification of persistent T cell responses to HSV in seronegative subjects is a novel finding in the herpesvirus field and suggests either undetected infection or acquired immunity in the absence of infection. Understanding the basis of these acquired immune responses may be critical in developing effective vaccines for genital herpes.

A chemiluminescence detection method of hantaviral antigens in neutralisation assays and inhibitor studies

A protocol for chemiluminescence detection of hantaviral antigens in infected cell foci is described. This focus detection is based on the conversion of a substrate into a luminescent product by peroxidase-antibody conjugates; the emitted light of infected cell foci can easily be recorded by autoradiography or video imaging providing a hard copy for documentation. The main advantage of this method as compared to conventional immunochemical staining is a higher detection sensitivity due to the inherent magnification effect of luminescence causing an obvious boost in focal image and intensity. This enables reduction of (i) incubation time of virus-infected cells and (ii) amount of needed antibody for antigen detection in foci. This method is applied to a chemiluminescence focus reduction assay for the serotyping of hantavirus-specific neutralising antibodies in infected persons and for the determination of activity of antiviral agents against hantavirus.

Immunochemiluminescent focus assays for the quantitation of hepatitis A virus and rotavirus in cell cultures

Two new immunological methods, the luminescent immunofocus assay (LIFA) and the luminescent immunofocus inhibition assay (LIF-IA), are described for the quantitation of cytopathic and non-cytopathic viruses propagated on cell culture monolayers. These methods use enhanced chemiluminescent detection to identify foci (luminescent immunofoci, LIF) of virus-infected cells. Viruses are propagated in susceptible cells under an agarose overlay, inactivated with ultraviolet irradiation, lifted onto nitrocellulose membranes, and probed with virus-specific monoclonal or polyclonal antibody followed by a second antibody conjugated to horseradish peroxidase. Membranes are then treated with a luminol-based detection reagent and exposed to light sensitive film for up to 10 min. The film is developed and foci appear as dark, discrete spots which are proportional to the dose of each virus. The LIFA detected both cytopathic and non-cytopathic hepatitis A viruses (HAV) and simian rotavirus. For the cytopathic HAV, the LIFA and plaque counts were comparable. The LIF-IA was developed for HAV using virus-specific antiserum which effectively attenuated LIF formation. The LIFA and LIF-IA may be completed 5 days faster than conventional radioimmunofocus assays for HAV and rotavirus and do not require the use of radiolabeled antibodies, offering safety advantages and making these techniques more adaptable for general use. Luminescent immunofocus assays should be useful for the detection and quantitation of virtually any cytopathic or non-cytopathic virus that can be propagated in monolayer cultures when virus-specific antiserum is available.

A monoclonal blocking EIA for herpes simplex virus type 2 antibody: validation for seroepidemiological studies in Africa

A competitive type-specific enzyme-linked immunosorbent assay (ELISA) for herpes simplex virus type 2 (HSV-2) antibody was developed using an infected cell antigen and a monoclonal antibody to glycoprotein G-2. This assay has been validated for use for epidemiological studies using a large panel of sera collected in rural Uganda and a panel of 143 sera characterised previously by Western blotting, the 'gold standard' for HSV type-specific serology. This evaluation was found to have a sensitivity of 96% and a specificity of 91% in comparison with Western blot on 143 sera from clinic patients. The ELISA had a sensitivity of 93% and a specificity of 91% in comparison with Western blot on 495 sera collected in Uganda. The assay showed good reproducibility and a low percentage of sera gave equivocal results, indicating its suitability for epidemiological studies.

Multiple trophic actions of heparin-binding epidermal growth factor (HB-EGF) in the central nervous system

The epidermal growth factor (EGF) family of ligands interacts with the epidermal growth factor receptor (EGF-R) to produce numerous direct and indirect actions on central nervous system cells. They induce the proliferation of astrocytes and multipotent progenitors ('stem' cells) and promote the survival and differentiation of postmitotic neurons. Heparin-binding epidermal growth factor (HB-EGF) interacts with both EGF-R and a related receptor, ErbB4, whereas transforming growth factor alpha (TGFalpha) interacts only with EGF-R. Because of the unique characteristics of HB-EGF and the potential utility of EGF family members in brain repair, we examine the effects of HB-EGF on rat and mouse CNS cells in vitro and compare them to those of TGFalpha. We find that, like TGFalpha, HB-EGF stimulates the proliferation of CNS astrocytes and multipotent progenitors. These proliferative effects require the expression of EGF-R, as no such effects are observed in cells derived from EGF-R-/- mice. Both HB-EGF and TGFalpha enhanced the survival of neurons derived from the neocortex and the striatum. Within these neuron-enriched cultures, nestin-positive cells but not neurons express EGF-R mRNA, indicating that the neurotrophic actions of EGF-R ligands are a result of indirect stimulation mediated by non-neuronal cells. The neurotrophic actions of HB-EGF and TGFalpha are accompanied by an elevation in immunoreactive dual phosphorylated mitogen-activated protein kinase (MAP kinase) in neurons, providing evidence that the MAP kinase cascade mediates these actions. In situ hybridization studies demonstrate that HB-EGF mRNA is present within the brainstem as early as E14 and subsequently is found in the developing cortical plate, hippocampus, cerebellar Purkinje cells and ventrobasal thalamus, among other brain areas. These findings indicate that HB-EGF may be an important trophic factor in the developing CNS and is a useful candidate molecule for brain repair strategies.

Chemiluminescence Western blot assay for the detection of immunity against parvovirus B19 VP1 and VP2 linear epitopes using a videocamera based luminograph

A chemiluminescent Western blot (WB) assay was developed to detect the immune status against linear epitopes of parvovirus B19 structural proteins VP1 and VP2. The chemiluminescent WB assay combined the sensitivity of chemiluminescent substrates and the objective evaluation of the luminescent signal obtained with a new system which consists of a videocamera-based, high-performance, low light level imaging luminograph connected to a personal computer for image analysis. The potential for diagnostic purposes was evaluated using reference serum samples and 75 clinical samples from patients with different clinical conditions and laboratory evaluations regarding B19 infection. The chemiluminescent Western blot assay provided reproducible results, an objective evaluation of the results and a semi-quantitative analysis of the presence of antibodies against VP1 and VP2 in human sera. The chemiluminescent Western blot assay proved more sensitive than the classic colourimetric Western blot assay.

Occult systemic infection and persistent simian immunodeficiency virus (SIV)-specific CD4(+)-T-cell proliferative responses in rhesus macaques that were transiently viremic after intravaginal inoculation of SIV

The intact cervicovaginal mucosa is a relative barrier to the sexual transmission of human immunodeficiency virus type 1 (HIV-1). In the simian immunodeficiency virus (SIV) macaque model of HIV infection, seronegative transient viremia (STV; virus isolation positive followed by repeated negative cultures) occurs after intravaginal inoculation of a low dose of pathogenic SIVmac251 (C. J. Miller, M. Marthas, J. Torten, N. Alexander, J. Moore, G. Doncel, and A. Hendrickx, J. Virol. 68:6391-6400, 1994). Thirty-one adult female macaques that had been inoculated intravaginally with pathogenic SIVmac251 became transiently viremic. One monkey that had been culture negative for a year after SIV inoculation became persistently viremic and developed simian AIDS. No other STV monkey developed persistent viremia or disease. Results of very sensitive assays showed that 6 of 31 monkeys had weak SIV-specific antibody responses. SIV-specific antibodies were not detected in the cervicovaginal secretions of 10 STV monkeys examined. Twenty of 26 monkeys had lymphocyte proliferative responses to p55(gag) and/or gp130(env) antigens; 3 of 6 animals, including the monkey that became persistently viremic, had detectable cytotoxic T-lymphocyte (CTL) responses to SIV. At necropsy, lymphoid tissues and vaginal mucosa were virus culture negative, but in 10 of 10 animals, SIV provirus was detected by PCR using gag-specific primer pairs. Fifty percent of the PCR-positive tissue samples were also positive for SIV gag RNA by reverse transcriptase PCR. Thus, transient viremia following intravaginal inoculation of pathogenic SIV is associated with persistent, systemic infection, either latent or very low level productive. Atypical immune responses, characterized by lymphocyte proliferation and some CTL responses in the absence of conventionally detectable antibodies, develop in transiently viremic monkeys.

Mucosal antibody expression following rapid SIV(Mne) dissemination in intrarectally infected Macaca nemestrina

The early kinetics of antibody expression following transmucosal infection by SIV(Mne) were examined in several mucosal compartments in Macaca nemestrina. Five male-female pairs of macaques were inoculated intrarectally with SIV(Mne) E11S, a biological clone, and serially euthanized at 1, 2, 4, 8, and 12 weeks postinoculation. Plasma, tears, saliva, rectal secretions, and vaginal washes were collected serially and just prior to euthanasia. Both total and SIV-specific IgG and IgA levels were measured by immunoglobulin isotype-specific quantitative enzyme-linked immunosorbent assays (ELISAs), and were further examined by conventional and enhanced chemiluminescence (ECL) immunoblots. Virus coculture, polymerase chain reaction, and in situ hybridization assays revealed the systemic spread of virus as early as 1 week postinoculation in 8 of 10 animals. ECL immunoblots detected SIV-specific antibodies in mucosal samples collected 1 week postinoculation. The most dramatic increases in both total and SIV-specific IgA levels were detected in rectal secretion samples. In contrast, plasma and nonrectal mucosal samples from the same time points increased only slightly, suggesting that the most robust antibody response occurred at the portal of infection. Our results show that the SIV-infected macaque is an excellent model for studies designed to assess mucosal immune responses to primate lentivirus infections. Additional studies will assess the correlation between the antiviral protection afforded by candidate vaccines and mucosal antibody responses.

Detection of Epstein-Barr virus-specific antibodies by an automated enzyme immunoassay. Performance evaluation and cost analysis

Detection of antibodies to specific antigens of Epstein-Barr virus (EBV) has been conventionally performed by an immunofluorescence assay (IFA). The procedure is labor intensive and expensive, and interpretation of results is subjective. We evaluated an automated enzyme immunoassay (EIA) (INC-STAR Corp., Stillwater, MN, USA) using 290 serum specimens submitted for the diagnosis of acute infection with EBV. Antibodies (IgG, IgM) to EBV capsid antigen and IgG class antibodies to the nuclear antigen of the virus were obtained using the LABOTECH Automated Microplate Analyzer (BioChem ImmunoSystems Inc., Allentown, PA, USA) and were compared to the antibody profile results obtained by IFA and Western blot as the "gold standard." For detection of acute infection with EBV (presence of IgM and IgG antibodies to the capsid antigen; absence of antibodies to the nuclear antigen), the EIA had 100% sensitivity (11 of 11) and 99% specificity (275 of 279) compared to IFA and Western blot results. A cost analysis of IFA and EIA procedures, based on an estimated annual volume of 12,000 procedures, indicated that $236,000 direct cost and 1,400 h technologist time could be saved with the automated compared with immunofluorescence procedure. The automated EIA for determination of antibodies provides cost-effective, accurate diagnosis of EBV infections in laboratories processing high numbers of specimens now processed by IFA.

Characterization of a monoclonal antibody and a cDNA for polyubiquitin of Amoeba proteus

A monoclonal antibody was obtained that reacts with many different proteins (14-200 kDa) of Amoeba proteus. By indirect immunofluorescence microscopy we found the antigens to be dispersed throughout the cytoplasm but were more concentrated in the nucleus. The antibody cross-reacted with proteins of Tetrahymena, Xenopus embryo, and mouse macrophages. Using the antibody as a probe we cloned a cDNA of 1.2 kb coding for ubiquitin in five repeats. Amino acid sequences of ameba's polyubiquitin showed the most variations among the nineteen polyubiquitins of other organisms compared. The well-conserved 20Ser and 55Thr residues were replaced with Gly and Ser, respectively. The 28Ala residue found in most organisms was replaced with Gln or Glu in the amoeba. Amoebae contained two ubiquitin-mRNAs that could be detected by Northern blot analysis using the cDNA as a probe. In an analysis for specificity, the antibody reacted with polyubiquitin and ubiquitin-fusion proteins larger than 14 kDa but not with monomeric ubiquitin. The antibody is a useful probe in the detection and characterization of proteins ubiquitinated in response to cellular stresses.

Focus luminescence assay: macroscopically visualized foci of human cytomegalovirus and varicella zoster virus infection

The plaques or foci of certain viruses due to their small size have to be counted microscopically, e.g., human cytomegalovirus (HCMV). The focus luminescence assay (FLA) described below generates macroscopic images as a result of the magnification due to scattered emitted light, and provides a hard copy using autoradiography or video imaging. Foci are detected according to an immunohistochemical protocol with horseradish peroxidase or alkaline phosphatase antibody conjugates which convert substrate into a luminescent product. Detection of varicella zoster virus (VZV) foci developed with a specific substrate-enhancer combination was so sensitive that 20-times lower primary antibody concentrations were effective than those required for conventional immunohistochemical staining. This method for HCMV and VZV may allow quantitative infectivity and focus reduction assays for viruses which produce little or no CPE.

FlaA, a putative flagellar outer sheath protein, is not an immunodominant antigen associated with Lyme disease

FlaA was recently found to be associated with flagellar filaments of Borrelia burgdorferi. We tested whether antibodies to this protein are a good indicator of infection, as antibodies to FlaA proteins in other spirochetal infections show an increase in titer. Although overproduction of intact FlaA was highly toxic to Escherichia coli, truncated proteins which lacked the N-terminal signal sequence could be successfully overexpressed. Immunoblotting with sera from mammalian hosts infected with B. burgdorferi indicated that FlaA is not an immunodominant antigen in Lyme disease. However, sera from two patients reacted with both recombinant and native FlaA protein, suggesting that B. burgdorferi FlaA was antigenic and expressed in vivo.

Frequent genital herpes simplex virus 2 shedding in immunocompetent women. Effect of acyclovir treatment

Reactivation of herpes simplex virus type 2 (HSV-2) occurs intermittently as perceived clinically and by viral culture. We performed a series of studies to evaluate the frequency and pattern of HSV-2 reactivation using both viral isolation and HSV PCR assay. Daily samples of genital secretions were obtained from 27 HSV-2 seropositive women; a subset of subjects obtained samples while receiving oral acyclovir 400 mg PO twice a day. HSV DNA was detected in genital swab specimens on 28% of 1,410 d compared with 8.1% of days by viral isolation. 11 of 20 women had HSV DNA detected on > 20% of days, 4 on > 50%, and 2 on > 75% of days; in contrast, none of the women shed on > 21% of days by viral isolation. The daily administration of oral acyclovir promptly reduced the frequency of HSV DNA detection by a median of 80%. Within 3-4 d of discontinuing daily acyclovir, HSV DNA again appeared in the genital area. HSV-2 shedding in the genital mucosa occurs much more frequently than previously appreciated. This frequent reactivation likely plays a role in the epidemic spread of genital herpes worldwide.

Herpes simplex virus type 2 detection by culture and polymerase chain reaction and relationship to genital symptoms and cervical antibody status during the third trimester of pregnancy

OBJECTIVES

Our goal was to define the frequency of asymptomatic herpes simplex virus type 2 shedding by culture and polymerase chain reaction and to correlate our findings with cervical anti-herpes simplex virus type 2 immunoglobulin A production.

STUDY DESIGN

Women who were seropositive for herpes simplex virus type 2 collected daily genital tract samples during the third trimester for culture and deoxyribonucleic acid quantitation by polymerase chain reaction. Cervical secretions were collected weekly for anti-herpes simplex virus type 2 immunoglobulin A. Asymptomatic shedding by culture versus polymerase chain reaction and anti-herpes simplex virus type 2 immunoglobulin A detection with and without genital shedding were compared by means of McNemar's chi 2 test.

RESULTS

Asymptomatic shedding was more frequent by polymerase chain reaction than by culture (13.8% vs 2.3%, p < 0.0001). When cervical anti-herpes simplex virus type 2 immunoglobulin A was present, patients were more likely to have negative results by polymerase chain reaction than positive results (66.7% vs 26.7%, p = 0.001). Anti-herpes simplex virus type 2 immunoglobulin A was detected beyond 37 weeks in only one subject.

CONCLUSIONS

Polymerase chain reaction was more sensitive than culture for detecting asymptomatic genital herpes simplex virus. The role of immunoglobulin A in clearing genital herpes simplex virus remains to be determined.

Automated microneutralization: method and comparison with western blot for type-specific detection of herpes simplex antibodies in two pregnant populations

A novel method for the detection of microneutralization was compared to Western blot for detection of type-specific antibodies to herpes simplex virus in two pregnant patient populations in Vancouver. From an unselected group of women in labor in a tertiary care obstetric hospital (426) and another group of women specially referred for assessment of genital herpes in pregnancy (195) 20 and 88%, respectively, were seropositive for herpes simplex virus type 2 antibodies by Western blot. During the study period, 93 (48%) of the high-risk group were culture positive for HSV-2 and all but one case was verified serologically by Western blot. Therefore, the sensitivity for Western blot in this high seroprevalence group was 99%. The false-negative case had longstanding recurrent infection and on retest was found to be a laboratory error. For microneutralization, type-specificity was especially difficult to distinguish among patients with mixed viral type patterns. Comparing microneutralization to Western blot as the gold standard, sensitivity, specificity, positive and negative predictive values were 84, 78, 97 and 40% respectively, for the referred group and 73, 82, 51 and 92%, respectively, for the unselected group. Poor negative and positive predictive values for the referred group and unselected populations, respectively, demonstrate that microneutralizations are not clinically acceptable for type-specific antibody detection. By contrast, serology by Western blot is very sensitive and apparently highly specific.

Monoclonal antibody blocking tests for the detection of HSV-1- and HSV-2-specific humoral responses: comparison with western blot assay

Monoclonal antibody blocking radioimmunoassays (MAb block RIAs) which detect specific humoral responses to each of the two human herpes simplex virus (HSV) types are described. RIAs were compared with Western blot assay (WBA) in a blind study of 64 sera obtained from clinically well-documented cases of genital herpes. WBA and MAb block RIA each detected HSV-1 antibodies in 16/17 (94%) sera from confirmed HSV-1 genital infections (first episodes and recurrent infections). Detection of HSV-2 antibody in 21 sera from HSV-2 first episodes was more effective by WBA which identified homologous antibody in 19 (96%), whereas MAb block RIA detected HSV-2 antibody in 16 (76%). HSV-2 antibody was detected in 24/25 (96%) sera from recurrent HSV-2 infections by WBA and by MAb block RIA, the highest degree of concordance for both methods. In addition, the MAb block RIA may be more effective in detecting the presence of HSV-1 antibody in sera from recurrent HSV-2 cases. Prevalence of HSV-1 and HSV-2 antibody was measured by the MAb block RIAs in 3 UK human study populations which consisted of 100 children/young adolescents, 104 adult blood donors and 80 genito-urinary medicine clinic attenders.

Vaccination with recombinant vaccinia viruses expressing ICP27 induces protective immunity against herpes simplex virus through CD4+ Th1+ T cells

This study was designed to evaluate the efficacy and mechanisms of protection mediated by recombinant vaccinia viruses encoding immediate-early (IE) proteins of herpes simplex virus type 2 (HSV-2). Three mouse strains were immunized against the IE proteins ICP27, ICP0, and ICP4, and mice were challenged intracutaneously in the zosteriform model with HSV-2 strain MS. Protection was observed only following immunization with the ICP27 construct and then only in the BALB/c mouse strain. Protection in BALB/c mice was ablated by CD4+ T-cell suppression but remained intact in animals depleted of CD8+ T cells. Moreover, protection could be afforded to SCID nude recipients with CD4+ but not CD8+ T cells from ICP27-immunized mice. Only BALB/c mice developed a delayed-type hypersensitivity reaction to HSV-2, and in vitro measurements of humoral and cell-mediated immunity revealed response patterns to ICP27 and HSV that differed between protected BALB/c and unprotected mouse strains. Accordingly, BALB/c responses showed antigen-induced cytokine profiles dominated by type 1 cytokines, whereas C57BL/6 and C3H/HeN mice generated cytokine responses mainly of the type 2 variety. Our results may indicate that protection against zosterification is mainly mediated by CD4+ T cells that express a type 1 cytokine profile and that protective vaccines against HSV which effectively induce such T-cell responses should be chosen.

Heat shock proteins of Toxoplasma gondii

We have investigated heat shock protein (HSP) expression in mouse-virulent and -avirulent strains of Toxoplasma gondii by performing Western blot analysis using a monoclonal antibody against HSP65 of Mycobacterium bovis and a polyclonal antiserum against HSP70 of Plasmodium falciparum as primary antibodies. We initially observed that murine macrophages express HSP65 when infected with either virulent or avirulent strains, a result which contradicts previous reports. Differential HSP expression consistent which virulence was observed between strains, with high levels of a 70kDa HSP (HSP70) only detected in virulent strains in vivo. This protein was not observed in virulent strains in the immunocompromised mouse or in vitro, suggesting induction by immunological stress. This protein was only poorly expressed in avirulent strains. A 65kDa protein was observed in all strains in vivo and in vitro, suggesting a shared epitope with HSP70. These results are consistent with the hypothesis that the induced expression of HSP70 in virulent strains of T. gondii by immunological stresses may provide protection for these strains against cell damage associated with invasion of the host, allowing the virulent strains to persist as tachyzoites without the requirement for the encystation observed in avirulent strains.

Quantitative dot-blot assay for low titer anti-lipopolysaccharide antibodies in human plasma

Low titer antibodies in plasma are very hard to detect by enzyme-linked immunosorbent assay (ELISA) mainly because of high nonspecific binding of various plasma proteins to the plastic substratum. In this report we present a sensitive and quantitative dot-blot assay which overcomes the high nonspecific binding problem and enables the detection of very low antibody titers in plasma. Natural low titer antibodies to Gram negative bacteria's lipopolysaccharide in plasma of healthy donors could not be detected by ELISA. However, by using nitrocellulose membrane as the carrier for the antigen and enhanced chemiluminescence as the detection method, we could detect and quantify low titers of anti-lipopolysaccharide antibodies even in undiluted plasma with no background interference. The dot-blot assay is linear, in semilogarithmic plot, over a broad range of plasma dilutions. This assay will enable the early detection of antigen specific antibodies in immune processes such as in infectious diseases and vaccination.

Cervical antibodies in patients with oral herpes simplex virus type 1 (HSV-1) infection: local anamnestic responses after genital HSV-2 infection

Herpes simplex virus (HSV)-specific immunoglobulin A, immunoglobulin G, and secretory-component-containing immunoglobulins were identified in cervical and salivary secretions from six subjects with oral HSV type 1 (HSV-1) infections. Anamnestic cervical and salivary antibody responses were detected in two HSV-1-seropositive women with newly acquired genital HSV-2 infections. These data implicate the common mucosal immune system in antibody responses to HSV.

Enhanced chemiluminescence as a means of increasing the sensitivity of western blot assays for HIV antibody

Chemiluminescence indicator systems offer several advantages for diagnostic assays and have been used successfully to increase the sensitivity of antibody and antigen assays. A technique of enhanced chemiluminescence (ECL) was applied as a replacement for routine chromogenic substrates on HIV-1 Western blots. The results indicated that the enhanced chemiluminescence detection system increased the sensitivity by greater than 10-fold over routine chromogenic indicator systems when testing diluted, reactive sera. When testing 9 seroconversion panels, the use of ECL indicated that early detection of HIV infection was elicited in six panels up to 31 days (average 11.4 days) prior to detection by routine FDA-licensed Western blots, and could be detected in all panels up to 43 days (average 18.8 days) prior to detection by in-house Western blots. In no case was the ECL Western blot system less sensitive than any of the chromogenic Western blots, and in several cases the maximum potential of the ECL system for early detection of antibody could not be determined. The ECL system was capable of detecting antibodies to envelope antigens at a 20-fold increase over chromogenic Western blots. The time of detection of seropositivity by the ECL Western blot was equal to that of most ELISAs in 5 panels and was 31 days earlier than ELISA in one panel. Permanent documentation of Western blot profiles was accomplished using a simple instamatic camera system capable of detecting the chemiluminescence signal, and blots could be re-probed using a second sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Laboratory techniques in the diagnosis of herpes simplex infection

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