Prozone effects in microscopic agglutination tests for leptospirosis in the sera of mice infected with the pathogenic Leptospira interrogans serovar Canicola

Shimabukuro, Fabio Hiroto; Costa, Veruska Maia da; Silva, Rodrigo da; Langoni, Hélio; Silva, Aristeu Vieira da; Carvalho, Lídia Raquel de; Domingues, Paulo Francisco

doi:10.1590/0074-0276108052013022

Cited by 4 publications

(3 citation statements)

References 8 publications

(12 reference statements)

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“…Some previous studies also reported similar phenomena (prozone effect) due to antibody excess in the agglutination test. 23 This is because excessive antibodies might bind to all the antigens and block all the epitope sites, while limited antibodies are able to bind more than one antigenic particle (pathogen) simultaneously and cause cross-linking. Thus, no subsequent agglutination reaction occurs in the excess of antibodies.…”

Section: ■ Discussionmentioning

confidence: 99%

Non-Neutralizing Epitopes Shade Neutralizing Epitopes against Omicron in a Multiple Epitope-Based Vaccine

Gong

et al. 2022

ACS Infect. Dis.

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The ongoing coronavirus disease 2019 pandemic has raised concerns about the risk of re-infection. Non-neutralizing epitopes are one of the major reasons for antibody-dependent enhancement. Past studies on the ancestral severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have revealed an infectivity-enhancing site on the ancestral SARS-CoV-2 spike protein. However, infection enhancement associated with the SARS-CoV-2 Omicron strain remains elusive. In this study, we examined the antibodies induced by a multiple epitope-based vaccine, which showed infection enhancement for the Omicron strain but not for the ancestral SARS-CoV-2 or Delta strain. By examining the antibodies induced by single epitope-based vaccines, we identified a conserved epitope, IDf (450−469), with neutralizing activity against ancestral SARS-CoV-2, Delta, and Omicron. Although neutralizing epitopes are present in the multiple epitope-based vaccine, other immunodominant non-neutralizing epitopes such as IDg (480−499) can shade their neutralizing activity, leading to infection enhancement of Omicron. Our study provides up-to-date epitope information on SARS-CoV-2 variants to help design better vaccines or antibody-based therapeutics against future variants.

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Section: ■ Discussionmentioning

confidence: 99%

Non-Neutralizing Epitopes Shade Neutralizing Epitopes against Omicron in a Multiple Epitope-Based Vaccine

Gong

et al. 2022

ACS Infect. Dis.

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“…Screening by MAT is done by using one dilution instead of a dilution series as described in Basic Protocol 1. Please be aware that reactive serum samples can be missed due to the prozone effect that might occur, notably when high concentrations of anti-Leptospira antibodies are present in the test sample (Shimabukuro et al, 2013).…”

Section: Microscopic Agglutination Test Screening Indirect Readingmentioning

confidence: 99%

Leptospirosis Serodiagnosis by the Microscopic Agglutination Test

2014

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The microscopic agglutination test (MAT) is the gold standard for sero-diagnosis of leptospirosis because of its unsurpassed diagnostic specificity. It uses panels of live leptospires, ideally recent isolates, representing the circulating serovars from the area where the patient became infected. A dilution series of the patient's serum is mixed with a suspension of live leptospires in microtiter plates. After incubating for about 2 hr at 30°C, results are read under the dark-field microscope. The titer is the last dilution in which ࣙ50% of the leptospires have remained agglutinated. Seroconversion or ࣙ4-fold titer rise in paired sera is consistent with current leptospirosis. The significance of a titer in a single sample depends on the frequency of residual titers due to past infections and cross-reacting other diseases in the population. Full standardization of the MAT is not possible, but quality assurance can be achieved by participation in the international MAT proficiency testing scheme.

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“…Both are transmitted mainly through the sexual route and affect populations with similar characteristics. HIV can be transported by secretions and transferred by genital ulcers[22] [23]. Serological tests for HIV have been requested in the patient in question, since complete screening is essential in individuals infected with any sexually transmitted disease, especially when it is known that an infection is a door to others, since they have the same means of dissemination.The diagnosis of syphilis is simple, depends on a good anamnesis, with em-phasis on sexual history and analysis of the lesion material to identify the treponema and/or serological tests.…”

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confidence: 99%

Secondary Syphilis in Man: Prozone Effect

Anjos¹,

Costa²,

Miguel³

et al. 2018

JBM

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Introduction: Syphilis consists in a systemic infect contagious pathology with a chronic character. The etiological agent consists of an anaerobic spirochete bacterium, Treponema pallidum. Laboratory diagnosis can be made through a direct investigation of the etiologic agent or non-treponemal (VDRL) and treponemal (FTA-Abs) serological tests. False-negative results are rare. Objectives: The present report presents a rare case of a man with a secondary syphilis syndrome who was initially undiagnosed due to the prozone effect, since he presented VDRL in low titers, and was later confirmed with a new diluted serum sample and VDRL and FTA-Abs, which were positive. Conclusion: A close look should be given to patients who, although the clinical condition is compatible, complementary exams may not be, and clinical cases should be carefully evaluated so that the patient is not treated late.

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Prozone effects in microscopic agglutination tests for leptospirosis in the sera of mice infected with the pathogenic Leptospira interrogans serovar Canicola

Cited by 4 publications

References 8 publications

Non-Neutralizing Epitopes Shade Neutralizing Epitopes against Omicron in a Multiple Epitope-Based Vaccine

Non-Neutralizing Epitopes Shade Neutralizing Epitopes against Omicron in a Multiple Epitope-Based Vaccine

Leptospirosis Serodiagnosis by the Microscopic Agglutination Test

Secondary Syphilis in Man: Prozone Effect

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