Rubella-specific IgG subclass avidity ELISA and its role in the differentiation between primary rubella and rubella reinfection

Morgan‐Capner

1990

Epidemiol. Infect.

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SUMMARYAn IgM capture enzyme-linked immunosorbent assay for rubella-specific IgM was used to assess the avidity of specific IgM by comparing the results obtained with and without a mild protein denaturant in the washing fluid used after incubation of IgM with rubella haemagglutinating antigen. An avidity index (Al) was calculated with AIs < 50% considered to indicate low avidity. Sera from recent primary rubella, rubella reinfection and from patients persistently reactive for specific IgM were tested. Urea and diethylamine (DEA) were compared as the protein denaturants. Twenty-six of 28 sera from cases of primary rubella gave an Al < 50% with DEA, compared with 25 of 28 with urea. Seventeen of 20 sera from cases of reinfection gave an Al > 50 % with DEA whereas only 14 of 20 had a similarly high avidity with urua. Eight of 10 sera from 4 cases of persistent specific IgM reactivity gave AIs > 50 % with DEA, although this was reduced to 5 when urea was used. Thus a difference has been demonstrated between the avidity of specific IgM in primary infection from that demonstrated after a secondary antigenic challenge (reinfection). This may help in serologically distinguishing primary infection from reinfection.

Section: Resultsmentioning

confidence: 99%

“…Assays which detect specific IgG subclasses [2] only occasionally help but determination of specific IgG avidity has proved of great value [3,4]. It has been shown that for the month after onset of the rash, rubella-specific IgG is of low avidity compared with specific IgG of longer duration and hence found in reinfection.…”

Section: Introductionmentioning

confidence: 99%

The avidity of specific IgM detected in primary rubella and reinfection

Morgan‐Capner

1990

Epidemiol. Infect.

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“…Relative avidity studies are useful for the differentiation between cases of primary and past infection or reinfection/reactivation in several viral infections [13,14,16,17,19,26,28], and it was hoped that they might provide a means of identifying cases of recent HIV infection. We therefore examined the relative avidity of anti-gp41, anti-p24 and anti-p17 antibodies in sequential and cross-sectional sera from cases of well-defined recent HIV seroconversion and of anti-gp41 and anti-p24 antibodies in sera from cases who have been HIV for longer than a year.…”

Section: Discussionmentioning

confidence: 99%

“…Anti-gp41 avidity studies were carried out using an ELISA technique which expresses the avidity of antibodies under examination relative to the avidity of antibodies from cases of long-term immunity [16,17,19]. Behring Anti-HIV-1/-HIV-2 kits were adapted.…”

Section: Remote Casesmentioning

confidence: 99%

“…0. Graphs of Abs 492 against the reciprocal of the log 10 of the serum dilution were plotted and the distance between the two curves measured (the DEA shift value [DSV]) [16]. Optimization of the DEA concentration was by chessboard titration with sera from cases early after seroconversion and from cases known to have been seropositive for longer than 1 year.…”

Section: Remote Casesmentioning

confidence: 99%

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Differential maturation of avidity of IgG antibodies to gp41, p24 and p17 following infection with HIV-1

Clinical and Experimental Immunology

Wilson²,

O’Toole

et al. 1996

SUMMARYWe have evaluated solid-phase ELISA IgG antibody avidity studies as a means of identifying cases of recent HIV-1 infection. Although separate studies on the avidity of anti-gp41 and anti-p24 antibodies in seroconvertors have been reported, a comparison of the ability of patients to simultaneously mature their immune response to more than one HIV antigen immediately following seroconversion appears to be lacking. We have demonstrated a maturation in anti-gp41 avidity which reflects the time since seroconversion in all cases. In contrast, however, only some patients produced high-avidity anti-p24 or anti-p17 antibodies during the same time span. While the avidity of anti-gp41 antibodies remained high in cases of non-recent HIV infection, even in the face of advanced disease, we have confirmed the findings of others that the avidity of anti-p24 falls before the onset of ARC or AIDS. Therefore, whilst the avidity of anti-gp41 antibodies could reliably be of value in identifying cases of recent HIV infection, the avidity of anti-p24 or anti-p17 antibodies could not, but may be of prognostic value, even at an early stage. The time taken to reach maximum anti-p17, anti-p24 and anti-gp41 titres was variable, but anti-gp41 titres, like anti-gp41 avidity, remained high. In contrast, anti-p24 titres fell, even during the early follow-up period in some seroconvertors. Anti-p24 antibody avidity, however, appeared to be a better predictor of disease progression in 'remote' cases than anti-p24 titre. The avidity and titres of these antibodies are presented in relation to the clinical details, p24 antigen status, CD4 and CD8 counts where these are known.Keywords anti-gp41 anti-p17 anti-p24 relative antibody avidity recent infection antibody titre

Relative functional affinity of specific anti-core IgG in different categories of hepatitis B virus infection

1997

J. Med. Virol.

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While resolution of hepatitis B virus (HBV) infection occurs in most cases, a carrier state can exist in which the HBV surface antigen (HBsAg) persists. Some carriers are also positive for the HBV "e" antigen (HBeAg), indicative of high viral replication. Others are HBV "e" antibody (anti-HBe)-positive carriers in whom there appears to be a fall in the level of viral replication with the appearance of antibodies against the "e" antigen. The former group of carrier is considered to be at a higher risk of transmitting HBV infection than the latter. In order that a carrier state may occur, some degree of tolerance to the infectious agent must exist. A study of the rate of increase of specific antibody avidity following infection provides a means of assessing the maturity of the immune response to an infectious agent. Since antibodies specific for the HBV core antigen (HBcAg) are produced in almost all cases of HBV infection and the HBeAg and HBcAg share a large number of amino acids and some B- and T-cell epitopes, the increase in the avidity of antibodies against the HBV core antigen (anti-HBc) in cases of acute, resolving HBV infection and in HBV carriers has, therefore, been studied. An increase in the avidity of specific antibody, similar to that seen in other viral infections, was observed following acute, resolving infection. However, low avidity antibody persisted longer in carriers who remained positive for HBeAg, whereas in cases where there were antibodies specific for HBeAg, the anti-HBc antibody was of high avidity. Analysis of sequential sera from carriers who seroconverted from HBeAg-positive to anti-HBe-positive showed that an increase in anti-core avidity could predate seroconversion from HBeAg-positive to anti-HBe-positive status. Thus, anti-HBc avidity studies may be of diagnostic and prognostic significance.