Virus-specific serum IgG, IgM, and IgA antibodies in cytomegalovirus mononucleosis patients as determined by immunoblotting technique

Immunoglobulin A-specific serodiagnosis of acute human cytomegalovirus infection by using recombinant viral antigens

The immunoglobulin A-specific reactivities of recombinant viral proteins from nine different reading frames of human cytomegalovirus were evaluated in enzyme-linked immunosorbent assay experiments. Antigen fragments of reading frames pUL32, pUL44, and pUL57 were identified as preferable antigens for immunoglobulin A serodiagnosis. Application of autologous fusion proteins which combine these polypeptides may be useful especially for the early detection of acute secondary human cytomegalovirus infection.

Immunoglobulin A and M patterns to human cytomegalovirus during recurrent infection in patients with AIDS using a modified western blot

Immunoglobulin A and M patterns to human cytomegalovirus (HCMV) were investigated in sera from actively HCMV infected AIDS patients (n = 61) and healthy HCMV seropositive controls (n = 28) by a Western blot method (modi-blotting) and ELISA. The Western blot showed a higher detection rate for both IgA (78.7% vs. 52.5%) and IgM (83.6% vs. 13.1%) than ELISA in the immunocompromised patients suffering from active HCMV infection. Of the healthy seropositive individuals, 35.7% and 21.4% had a weak positive IgA- and IgM-class antibody reactivity respectively with HCMV-specific bands in the immunoblot. Immunoglobulins M and A were not detected by ELISA in the healthy control group. Immunoreactions in this group were restricted to viral polypeptides with M(r) of 68 kDa and 123 kDa. Additional bands were found in the actively infected patients only and were observed more frequently with IgA than IgM (47.5% vs. 29.5%). Results from the present study indicate, that using a sensitive Western blot technique, a higher serologic detection rate of active recurrent infection is achieved in AIDS patients. Nevertheless, immunoglobulin A and M are detected in a certain percentage of HCMV-seropositive healthy individuals not suffering from active HCMV infection. Broader immune reactions of HCMV-IgA as determined by HCMV Western blot assay are associated with an active infection, but were not present in all the actively infected patients.

Lack of correlation between virus detection and serologic tests for diagnosis of active cytomegalovirus infection in patients with AIDS

The aim of this study was to evaluate the usefulness of serologic analysis for the diagnosis of active cytomegalovirus infection in patients with AIDS. Active cytomegalovirus infection was diagnosed by virus isolation from urine and saliva and detection of antigenemia. Serologic analysis was done by several conventional and innovative procedures. The results indicate no correlation between any of the most popular serologic procedures and virus detection by culture in urine or saliva or antigenemia.

Temporal patterns of immunoblot-reactive antibodies to cytomegalovirus in transplant recipients

A total of 234 sera from 44 allograft recipients were compared with 12 sera from 9 immunocompetent patients with symptomatic cytomegalovirus (CMV) infection and with 20 sera of 20 healthy individuals with latent CMV infection. The presence of immunoreactive proteins was not associated with a specific transplant group or with different immunosuppressive regimens but rather with the kinetics of the immune response. Acute phase sera demonstrated early antibodies to proteins p38 and p48, followed by high or still rising antibodies to high molecular weight proteins, particularly p150, and their later decline to persistent lower levels. Convalescent phase sera were identified serologically by the transient appearance of IgG antibodies directed to 22-26 kDa polypeptides. Immunoreactive p44 was present in 85% of all patients with mild disease and in 40% of all patients with severe CMV disease. When tested in parallel, the immunoblot analysis was shown to be a more sensitive indicator of early CMV antibodies in allograft recipients than the ELISA technique.

A method for detecting specific anti-C100 protein antibodies of IgM isotype in hepatitis C virus infection

A method for the determination of specific IgM antibodies to C100 protein, a hepatitis C virus-associated antigen, was developed which employed fractionation of serum proteins by gel chromatography and an enzyme-linked immunosorbent assay. Detection of IgM anti-C100 proved to be specific and reproducible in purified IgM fractions. Separation of IgM from IgG was necessary before IgM could be measured, because of the detrimental effect of the simultaneous presence of IgG antibodies with anti-C100 rectivity on IgM determination. IgM anti-C100 was not found in sera containing rheumatoid factors or IgM antibodies to other hepatotropic viruses. IgM anti-C100 was detected in 19 (44%) of 43 patients with hepatitis C virus-related chronic liver disease. When compared with the histological picture of liver disease, IgM anti-C100 was absent in patients with minimal changes and was most common (66.7%) in patients with progressive disease. It is suggested that IgM anti-C100 could reflect an active state of hepatitis C virus infection.

Sequential serological studies of homosexual men with and without HIV infection. Epstein-Barr virus activation preceding and following HIV seroconversion

Viral cofactors may be important in the pathogenesis of HIV infection and the development of AIDS, but their role is still imperfectly understood. Sequential serological studies were performed in a cohort of 100 homosexual men and 70 matched healthy controls over a mean period of 4 years. Of the patients, 18 were found to be HIV+ on admission to the study and 15 seroconverted to HIV+ during the follow up (seroconversion group). Serum antibodies of both IgG and IgA isotypes against Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were determined. IgG antibodies indicate past infection, while a marked increase in IgG titre or a positive IgA titre were taken to indicate active infection or reactivated latent infection. EBV and CMV infections were about two to four times more prevalent in the homosexual men both HIV- and HIV+, compared with controls. Active infections were increased in the homosexual men and particularly in the HIV+ patients. The seroconversion group revealed activation of both EBV and CMV following HIV infection. When the antibody profile of seroconverting patients at the time preceding seroconversion was compared with a matched group of 39 homosexual men who remained HIV-, no change was found in CMV antibodies, but four out of 15 (26.6%) of the patients had high titres of anti-EBV IgA preceding seroconversion, as compared with only one out of 39 (2.6%) of HIV- homosexual men (P less than 0.05). This suggests a role for EBV reactivation in the pathogenesis of HIV infection in some patients.

Protein blotting: ten years on

Protein blotting was originally described in 1979 as an outgrowth of nucleic acid techniques, and received its commonly used designation of 'Western' blotting in 1981. The use of the technique to render electrophoresed proteins accessible for further analysis has found many roles, the most prominent being subsequent reaction with antibodies or antisera, which has many clinical and research applications. Since the initial development of the system there have been many changes to the techniques involved, but the basic principles remain unaltered. This review discusses these changes, and also provides a summary of current techniques.

Analysis of human antibody responses to human cytomegalovirus envelope glycoproteins found in two families of disulfide linked glycoprotein complexes designated gC-I and gC-II

Human antibody responses to human cytomegalovirus (HCMV) envelope glycoproteins were analyzed using immunoaffinity purified glycoproteins and Western blotting. Two families of disulfide linked glycoprotein complexes, designated gC-I and gC-II, were isolated. These complexes were reduced and their individual glycoproteins separated by polyacrylamide gel electrophoresis prior to electroblotting. The reactivity of adult convalescent sera with individual glycoproteins was compared to that of sera from congenitally infected infants. All sera tested reacted with a 52,000 molecular weight glycoprotein from these complexes, but only 75% reacted with a 93,000 to 130,000 molecular weight glycoprotein from gC-I complexes. Most adult convalescent sera reacted with glycoproteins from gC-II complexes. However, 14 of 16 infant sera did not have high enough levels of gC-II antibodies to give a positive reaction with Western blotting. A longitudinal study was done with several infants and their mothers. These studies indicated a failure by the infants and their mothers to develop detectable levels of gC-II antibodies months to years after the initial infection or after repeated stimulation with HCMV due to persistent infection. The inability of these infants to develop significant levels of gC-II antibodies was not due to an inability to respond to viral glycoproteins since they had antibodies to gC-I glycoproteins. We also determined that the strains of HCMV infecting some of these infants expressed gC-II glycoproteins. Thus, the lack of response by these infants was not due to lack of expression of gC-II glycoproteins by their infecting strain.

Detection of immunoglobulin G, M, and A antibodies to enterovirus structural proteins by immunoblot technique in echovirus type 4-infected patients

Paired serum specimens from 24 patients with echovirus (EV) type 4 infection by virus isolation were tested by the immunoblot technique for the presence of IgG, IgM, and IgA antibodies to EV4 structural proteins. Single sera from 20 patients without neutralizing enterovirus IgM were used as controls. All the sera from EV4-infected patients had IgG antibodies to VP1 of EV4 but also 13 out of the 20 controls. 23 out of 24 EV4-infected patients elicited IgM and IgA specific antibodies to VP1, a pattern highly significant as compared with controls (3/20 for IgM and 8/20 for IgA). In 16 out of the 24 EV4-infected patients, the IgM antibodies were also directed against VP2 (versus 2 out of 20 in the control group). Anti-VP2 IgA were detected in 4 out of the 24 EV4 patients (versus 0 in controls). The 24 paired sera from EV4-infected subjects were also tested by immunoblot technique against three other enteroviruses: EV21, coxsackievirus A9 and poliovirus 1. Cross-reactivities were observed to a large extent against VP1 and VP2 proteins with the three classes of antibodies. These results confirm the data of previous studies on the reactivity of IgM antibodies to various structural proteins that IgG antibodies react exclusively to VP1. Furthermore, this study demonstrates the occurrence of circulating IgA antibodies directed to VP1 and sometimes VP2 in the course of enterovirus infection. The potential interest of this latter finding for diagnosis requires further investigation.

Detection of anti rotavirus coproantibodies by immunoblotting technique

IgA and IgG coproantibodies to individual simian rotavirus (SA 11) structural polypeptides were detected in healthy infants in nursery homes. The number of immunoblottable peptides differed from individual to individual. Coproantibodies were also detected at the convalescent stage of rotavirus infection in two patients but not during the acute stage. This method is useful for confirming the diagnosis of rotavirus infection serologically without the need for paired sera.

Pattern of anti-cytomegalovirus IgM antibodies determined by immunoblotting. A study of kidney graft recipients developing a primary or recurrent CMV infection

In order to improve the knowledge of the humoral immune response to CMV infection, we developed an immunoblotting technique which allowed a better analysis of the changes in the pattern of anti CMV-polypeptides IgM. We examined 234 sera belonging to 27 renal allograft recipients developing a primary or recurrent CMV infection and 12 non infected recipients. Thus we found that 11 main anti CMV-polypeptides IgM antibodies were present in over 25% of the infected patients. They reacted with proteins whose molecular weights ranged from 32K to 205K. We showed that anti-p 45-47 IgM antibodies were present in 100% of CMV infected recipients and never in the non-infected population. They appeared very early in the course of the infection (5.43 weeks post-graft for primary infection and 5.00 weeks for recurrent ones) and, therefore, constitute a good marker of active infection. Two other CMV-specific IgM antibodies (anti-p 60-64 and anti-p 100) were found exclusively in the course of primary infections. Anti-p 60-64 IgM was observed at a high frequency (57.1%) and with a mean delay of 6.57 weeks post-graft. Therefore, the anti-p 60-64 IgM detection could be helpful for the diagnosis of primary infection. In almost 100% of both primary and recurrent infections, we observed anti-p 140 and anti-p 38 IgM antibodies. Only about 50% of non-infected patients had low levels of anti-p 140 and anti-p 38 IgM. The follow-up of recurrent infections showed that the anti CMV-polypeptides IgM antibodies appeared earlier than in primary infection. When we compared anti-p 45-47 IgM detection by immunoblotting and anti-CMV IgM detected by ELISA we observed that immunoblotting permitted the diagnosis 2.5 weeks earlier for primary infection, and 1 week earlier for recurrent infection, than ELISA. In addition, the detection of anti-p 45-47 IgM antibodies also occurred earlier than virus excretion.

Determination of human antibodies to specific antigens of cytomegalovirus using an antigen capture immunoassay

The antigen capture immunoassay which is described herein is based on the binding of specific antigens of cytomegalovirus (CMV) by monoclonal antibodies bound to a solid phase. The specificity of the binding was demonstrated by the analysis of antigens labelled with [35S]methionine and captured by the bound monoclonal antibodies. These specific antigens are recognized in turn by specific anti-cytomegalovirus antibodies in human sera. The immunoassay permits quantitation of these specific anti-cytomegalovirus antibodies and should facilitate both qualitative and quantitative comparisons of the antibodies against specific CMV antigens in different individuals.

Detection of anti-rotavirus IgG, IgM, and IgA antibodies in healthy subjects, rotavirus infections, and immunodeficiencies by immunoblotting

Immune responses to individual simian rotavirus (SA 11) structural polypeptides were studied with emphasis on specific IgG, IgM, and IgA in paired sera from four children with rotavirus infections. Responses to simian rotavirus (SA 11) were also studied in 103 healthy children, 10 patients with primary immunodeficiency who received intravenous immunoglobulin, and 11 human immunodeficiency virus antibody-positive patients. All samples were immunoblotted for two major polypeptides--VP2 and VP6--of IgG. Immunoblotted IgA and IgM were elevated 2-4 weeks after the onset of the disease (stage II) in patients with rotavirus infection. Immunoblotted IgG remained almost the same at the onset of the disease and stage II. The scores for primary and secondary immunodeficiency patients were lower than for healthy children. The score obtained by totaling all polypeptides found in each individual was compared with the optical density (OD) value obtained by enzyme immunoassay.

Antibodies to human cytomegalovirus structural polypeptides during primary infection

This study aimed at broadening the understanding of the immunogenic potential of cytomegalovirus (CMV) structural polypeptides during natural infection and to ascertain their possible use in serological diagnosis. Immunoblotting was used to analyse the appearance and development of serum IgG and IgM against human CMV structural polypeptides in sequential sera from renal transplant recipients during the first 1-3 months of primary CMV infection. The results showed that the first IgG to appear is specific for a polypeptide of 66 kDa and these antibodies appear either alone or together with others against another polypeptide of 82 kDa. IgG to the 150 kDa protein appears at least one week later. The first IgM to appear reacts preferentially with a 38 and 66 kDa polypeptide. The early detection of antibody against the major viral antigenic proteins in the diagnosis of CMV primary infection is discussed.

Genomic localization of the gene encoding a 32-kDa capsid protein of human cytomegalovirus

We have determined the map position of a viral gene encoding a 32-kDa late structural protein of human cytomegalovirus (HCMV) using a murine monoclonal antibody. This monoclonal antibody was reactive with two protein bands of 32 and 27 kDa in HCMV-infected cell lysates and with a single 32-kDa protein band in HCMV virions as detected by immunoblot analysis. When purified HCMV envelope preparation was used for immunoblotting, the monoclonal antibody did not display a detectable band. We used this monoclonal antibody to screen a cDNA library that was constructed from poly(A)+ RNA of late HCMV-infected cells and cloned into the expression vector lambda gt11. A cDNA clone that expressed an immunoreactive epitope of the late HCMV protein fused to beta-galactosidase was identified. Probing the restriction digests of HCMV (Towne and AD169) DNA with insert DNA from the immunoreactive lambda gt11 clone permitted us to localize the coding sequence within the long unique region between map coordinates of 0.62 and 0.64 of HCMV Towne and AD169 genomes. Using the same probe, a single transcript of 1.4 kb was detected in total RNA from HCMV-infected cells at late times after infection.