Evaluation of a Commercial Immunoblot, Helicoblot 2.1, for Diagnosis of Helicobacter pylori Infection

Abstract

The best method to diagnose Helicobacter pylori infection in different clinical situations is controversial. The aim of the study was to assess the performance of a commercial immunoblot, Helicoblot 2.1. The study comprised 215 patients, who were grouped according to the presence of H. pylori infection (assessed by two gastroscopies including histology with a median interval of 7.1 years, enzyme immunoassay [EIA]-based serology, and history of previous H. pylori infections and eradication therapies) into four categories: no H. pylori infection ever, previous infection, ongoing infection, and EIA seropositivity as the only marker of a possible previous infection. The sensitivity of Helicoblot 2.1 to show an ongoing or previous H. pylori infection was 100% and 92%, respectively. Helicoblot 2.1 was negative in only 80% of individuals with no evidence of present or previous infection but in 96% of patients 50 years of age or younger. The current infection marker of the immunoblot was positive in 49% of patients with successful H. pylori eradication therapy. After successful eradication therapy, Helicoblot 2.1 sustained positive results in 87% of patients, and CagA positivity was detected in 87% of patients with follow-up samples for more than 10 years after therapy. Helicoblot 2.1 is a sensitive and, among patients of ages 50 years or younger, a specific test in the primary diagnosis of H. pylori infection. However, it does not discriminate between past and current infections. It can be used in epidemiological studies assessing the role of H. pylori in different late sequelae.

Helicobacter pylori Infection and Gastric Cancer Risk: Evaluation of 15 H. pylori Proteins Determined by Novel Multiplex Serology

“…There are two plausible explanations for this finding. First, the difference in seropositivity of CagA (75.6%) and of the screening ELISA (66.1%) in GC cases suggests that CagA may have a much stronger antigenicity compared with some other immunogenic proteins, and thus, antibodies against it persist longer after clearance of the infection (23)(24)(25)(26). Second, as shown in Table 6, lower proportions of CagApositive strains were observed among H. pylori-infected controls compared with H. pylori-infected GC cases.…”

“…There is evidence that antibodies to CagA can persist longer after the eradication of H. pylori infection and estimates of the association between Table 4. Backward stepwise multivariate logistic regression exposure to H. pylori and GC were highly increased when CagA serostatus was considered combined with the screening ELISA (25). To our knowledge, the present study is the first epidemiologic study on GC risk simultaneously investigating antibodies to 15 different H. pylori proteins using multiplex serology.…”

Clonaje y expresión de un fragmento recombinante del gen cagA de Helicobacter pylori y su evaluación preliminar en el serodiagnóstico

“…Interesting, among the 13 false negative samples obtained with the Western-rCagA, 9 were classified as H. pylori negative CagA positive by HB 2.1. It is though that CagA seropositivity in H. pylori-seronegative subjects may either be a sign of a past H. pylori infection due to the long life of anti-CagA antibodies (18,28) or represent a false positive reaction (29). Therefore, probably the rCagA of this study may not contain the epitopes causing either of the above mentioned events that should be, if demonstrated, an advantage of this recombinant fragment to diagnose CagA-positive H. pylori infection.…”

“…Several studies using diagnostic methods to detect CagA antibodies have demonstrated that this antigen improve the sensitivity of H. pylori detection (18). Also, it has been observed that the positivity for CagA antibodies has the ability to predict the development of atrophy and appears related with young gastric cancer cases (10).…”

Serum <i>Helicobacter Pylori</i> IgG Titers are Predictive of <i>H. pylori</i> Infection Status

“…Moreover, serum IgG to H. pylori Cag A antigen persists for a long time after H. pylori disappearance 10 , in some cases for several decades. According to Veijola et al 11 , anti-Cag A IgG levels decrease only slightly after a number of years, and 87 of patients remain positive after 10 years. In the present study we showed that the antibody titer of patients with previous H. pylori infection is higher than that of patients naïve to H. pylori infection, although the antibody titer after H. pylori disappearance may decrease over time to below the limit of detection.…”