Recent Primary Toxoplasma Infection Indicated by a Low Avidity of Specific IgG

Hedman, Klaus; Lappalainen, Maija; Seppäiä, Ilkka; Mãkelä, O.

doi:10.1093/infdis/159.4.736

Cited by 299 publications

(246 citation statements)

References 26 publications

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“…However, in order to demonstrate their usefulness, it is not enough to show that the mean response of those infected recently is different from those infected in the past [10]. Large-scale studies are required on patients whose primary toxoplasmosis infection has a known date of onset, with repeat samples every month for at least a year.…”

Section: Discussionmentioning

confidence: 99%

“…The use of such tests in prenatal screening programmes has been recommended by several experts [2,9]. Tests for IgG-avidity [10] or toxoplasma-specific IgA [11], which may also be able to discriminate recent from past infection, have also been proposed.…”

Section: Introductionmentioning

confidence: 99%

“…Test response related to time since infection: IgG-avidity A more precise diagnosis may be possible in a test such as IgG-avidity, which gives a continuous response that can be related, in a more or less linear fashion, to time since infection [10]. A regression of test response against time since infection is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluating the sensitivity and predictive value of tests of recent infection: toxoplasmosis in pregnancy

Ades

1991

Epidemiol. Infect.

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SUMMARYThe diagnosis of maternal infection in early pregnancy depends on tests which are sensitive to recent infection, such as specific IgM. Two types of test are considered: those where the response persists for a period following infection and then declines, such as IgM, and those whose response increases with time since infection, such as IgG-avidity. However, individuals vary in their response to infection, and it may not always be possible to determine whether an infection occurred during pregnancy or before it. Mathematical methods are developed to evaluate the performance of these tests, and are applied to the diagnosis of toxoplasmosis in pregnancy. It is shown that, based on existing information, tests of recent infection are unlikely to be both sensitive and predictive. More data on these tests are required, before they can be reliably used to determine whether infection has occurred during pregnancy or before it.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluating the sensitivity and predictive value of tests of recent infection: toxoplasmosis in pregnancy

Ades

1991

Epidemiol. Infect.

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“…The method of Hedman and colleagues [27] was adapted. Nunc Polysorp microtitre plates were coated with recombinant p24-GST (Escherichia coli ) fusion protein at 2 g/ml (ADP 634, MRC AIDS programme) in carbonate/bicarbonate coating buffer overnight at 48C.…”

Section: Anti-p24 Aviditymentioning

confidence: 99%

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

Thomas

Wilson²,

O’Toole

et al. 1996

Clinical and Experimental Immunology

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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

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“…The development of commercial assays and the use of ultra-sensitive techniques such as IgM capture tests increased the sensitivity of these assays, but resulted in extended periods of IgM presence after acute infections, with consequent loss of screening efficiency (SUZUKI et al, 2001). IgG avidity was introduced for temporal definition of viral infection in rubella (LEHTONEN & MEURMAN, 1982), and was adapted to toxoplasmosis to distinguish recent and old infections (HEDMAN et al, 1989). Avidity is based on the binding strength of specific IgG to a multivalent antigen of the parasite, which is produced at low concentrations after the primary infection, but is selectively increased over time.…”

Section: Introductionmentioning

confidence: 99%

Serology using rROP2 antigen in the diagnostic of toxoplasmosis in pregnant women

Macre¹,

Pires²,

Meireles³

et al. 2009

Rev. Inst. Med. trop. S. Paulo

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SUMMARYToxoplasma gondii causes severe fetal disease during acute infection in pregnant women, thus demanding early diagnosis for effective treatment and fetus preservation. Fetal tests are inefficient and risky, and diagnosis is based on maternal IgM serology, which had weak screening ability due to increased sensitivity, with alternative IgG avidity tests. Here, we performed ELISA and avidity assays using a recombinant T. gondii antigen, rROP2, in samples from 160 pregnant women screened from a large public hospital who were referred due to positive IgM assays. IgG serology and avidity assays were compared using whole T. gondii extract or rROP2. ELISA IgG detection with rROP2 showed good agreement with assays performed with T. gondii extract, but rROP2 IgG avidity assays were unrelated to whole extract antigen IgG avidity, regardless of the chaotrope used. These data show that avidity maturation is specific to individual antigen prevalence and immune response during infection. ELISA rROP2 IgG assays may be an alternative serological test for the diagnosis of toxoplasmosis during pregnancy, although our data do not support their use in avidity assays.

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Recent Primary Toxoplasma Infection Indicated by a Low Avidity of Specific IgG

Cited by 299 publications

References 26 publications

Evaluating the sensitivity and predictive value of tests of recent infection: toxoplasmosis in pregnancy

Evaluating the sensitivity and predictive value of tests of recent infection: toxoplasmosis in pregnancy

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

Serology using rROP2 antigen in the diagnostic of toxoplasmosis in pregnant women

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