Diagnosis of Yersinia infections accompanied by reactive arthritis could be complicated by cross-reaction with other arthritogenic bacteria. The possible cross-reaction between Yersinia antigens and anti-Borrelia antibodies in blood sera of patients with Lyme disease was studied. The occurrence of specific IgA, IgG and IgM antibodies was analyzed in serum samples from 30 patients with Yersinia-triggered reactive arthritis, 30 patients with Lyme disease and five samples from healthy blood donors. For anti-Borrelia IgG antibodies, cross-reaction was detected with YopH, YopB, V-ag, YopD, YopN, YopP and YopE, and for IgA with YopD. For IgM, no cross-reaction was detected. Owing to cross-reactivity with Borrelia, the diagnosis of Yersinia-triggered reactive arthritis should be based on a combination of serological and clinical findings.
In a representative nationwide study, we have determined the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) coinfections among HIV-positive patients diagnosed during the period 2010-2014 in Bulgaria. Despite a relatively low rate of new HIV diagnoses, the rates of hepatitis B and C coinfections among these patients fell within the upper range reported in Europe. HBsAg and HCV antibodies (Ab) were found in 10.4% and 25.6% of the tested individuals, respectively. Importantly, high rates of active hepatitis infections were confirmed by detection of HBV DNA in 51.1% and HCV RNA in 78.1% of the tested individuals. Hepatitis coinfections affected mostly high risk groups and persons with multiple risk behavior, including people who inject drugs, men who have sex with men, prisoners, and Roma people.
Background: Dried blood spots (DBS) have been used to study the prevalence of hepatitis B virus (HBV) infection in endemic areas and in high-risk groups. However, detection of HBV serological markers in DBS by ELISA assays has not yet been fully optimised. The aim of the present study is to evaluate the dilution level of anti-HBs when DBS cards are used as storage matrix implemented for ELISA. Material and methods: Antibodies against hepatitis B surface antigen (anti-HBs) were detected by ELISA. The following specimens were examined: serum samples from 20 patients paired with 20 DBS; serum samples from 20 HBV-vaccinated healthcare workers paired with 20 dried serum spots (DSS); and four different dilutions of Immunovenin. Different elution protocols were used in order to study the problem with sample dilution. Results: Specificity of 100% and sensitivity of 45% were established for DBS versus the “gold standard”. Dilution of the eluted DBS/DSS samples was established and in some cases the measured anti-HBs titre dropped under 10 mIU/ml. Correlation was not observed between the positive initial anti-HBs serum titres and the obtained values of DBS/DSS testing. Also, 20- to 50-fold dilutions were measured for eluted DSS samples when testing Immunovenin. Increasing of the eluted sample concentration raised DSS anti-HBs titre. Conclusions: In order to resolve the problem of dilution, it is necessary to validate different elution protocols because the small amount of sample in DBS showed lower titres.
Experimental oral infection of pigs with a parental Yersinia pseudotuberculosis strain pIB102, serotype O:3 and two mutant isogenic strains - pIB155,DeltayopK and pIB44,DeltaypkA has been carried out. Clinical findings, microbiological and immunological parameters were examined in dynamics from day 7 to day 60 post-infection (p.i.). All types of infections ran asymptomatically, without hyperthermia, loss of appetite, etc. Experiments on the blood parameters demonstrated a transient leucocytosis with lymphocytosis and monocytosis better expressed after yopK infection. Even though pig is usually known as a reservoir of yersiniae, bacterial colonization was found in mesenterial lymph nodes and tonsils on day 7, respectively 14 p.i. with parental strain, and only in tonsils on day 14 p.i. with both mutant strains. The augmented sensitivity of mutants to the bactericidal effect of leukocytes and blood sera is the characteristic feature of attenuation in their pathogenicity, compared to the parental strain. Comparative in vitro experiments on the immune response and immunostimulating capacity of Y. pseudotuberculosis mutant strains verify their preserved immunogenic potential, predominantly in case of yopK. Hyperplasia and strong activation of the lymph tissue of Peyer's patches, mesenterial lymph nodes, tonsils and spleen of pigs challenged with both mutant strains were proved as immunomorphological rearrangements. The results obtained give the reason to claim that the genetically constructed yopK null mutant strain is significantly attenuated but is still immunogenic and has the potential for a live vaccine carrier strain.
This study aimed to determine the frequency of detection of measles and rubella antibodies in dried blood spots in Bulgaria. Material and Methods: Two types of clinical material, serum samples and dried blood spots (DBS), were tested from a total of 101 patients. Serological methods (indirect ELISA) were used for detection of specific viral markers (IgM and IgG antibodies) indicating acute or past measles and rubella infection. Results: In the present study, the patients were with median age of 39 years and divided into 11 age groups. The majority of patients were under 30 years of age and from the capital of Sofia. In 3 patients acute measles infection was confirmed by positive ELISA-IgM results for the serum samples and DBS. No acute rubella infection was detected. Measles and rubella IgG seroprevalence was determined as 83/101 (82%, 95% CI: 74.51÷89.49) and 79/101 (78%, 95% CI: 69.92÷86.08) in serum samples, and 79/101 (78%, 95% CI: 69.92÷86.08) and 73/101 (72%, 95% CI: 63.25÷80.75) in DBS, respectively. In combination with immunoenzymatic testing for measles and rubella IgM/IgG markers, coincidence of results for both types of clinical material was found in >90% of cases. No significant differences were found in the results in terms of gender and age. Conclusion: In recent years a variety of new and innovative applications of DBS are introduced in medicine, neonatology, virology, microbiology, etc. The optimisation of the DBS technique as an alternative approach to venepuncture in virology is very important for conducting seroepidemiological studies and to a certain extent for the surveillance of epidemic outbreaks.
Introduction: Diagnosis of chronic hepatitis B virus (HBV) infection particularly its occult form requires monitoring and repeat serological and molecular studies. The aim of the study was to investigate the possible relation between the case of a family outbreak of hepatitis A and the finding that a member of this family was diagnosed with chronic hepatitis B. Methodology: A mother and her two sons, one previously diagnosed with chronic HBV infection, were hospitalized due to suspected acute hepatitis. Serological markers for hepatitis A, hepatitis B and hepatitis C were assessed. Additionally, HBV DNA was tested with a sensitive PCR. Hepatitis B vaccine was administered to the mother to differentiate resolved from occult HBV infection. Results: A family outbreak of hepatitis A was confirmed, alongside a focus of chronic HBV infection. The serological profile for two brothers was HBsAg(+), anti-HBcIgM(-), anti-HBc(+), HBcAg(-)/anti-HBe(+). The mother was negative for all HBV markers except anti-HBc. HBV DNA was detected at a level of 461 IU/mL in the elder brother, 3647 IU/mL in the younger brother and was negative in the mother on two occasions. Her anti-HBc alone, having two sons with chronic HBV infection, and her lack of antibody response to hepatitis B vaccine despite being negative for HBV DNA, led to the diagnosis of probable occult HBV infection. Conclusion: Our results confirmed that a vaccination approach could facilitate diagnosis of chronic HBV infection in the presence of isolated anti-HBc. If it were not for a family outbreak of hepatitis A, this unexpected family HBV focus would not have been revealed.
Background. Among the various serological markers employed in the hepatitis B virus (HBV) differential laboratory diagnosis, serum HBsAg is considered the most reliable. In order to characterise the HBV infection, another important diagnostic marker is employed – the HBc antibody (anti-HBc). There are three categories of anti-HBc-positive individuals: patients with HBV immunity, patients with chronic HBV and individuals with the so-called isolated anti-HBc pattern. The current study aimed to evaluate the presence of anti-HBc in patients negative for HBsAg whose clinical diagnosis was acute viral hepatitis. Material and methods. A total of 88 specimens were examined, of which 75 sera were from prospective patients diagnosed with acute viral hepatitis, and 13 sera from breast milk donors. Antibodies against the hepatitis B core antigen were detected by enzyme-linked immunosorbent assay (ELISA). Results. Twenty-eight (32%) of all tested samples were positive for anti-HBc. Nineteen samples belonged to male and 9 to female patients. One positive sample was from a breast milk donor. Two age groups, namely 46-55 years and 56-65 years, demonstrated the highest rate of anti-HBc positivity. Among the other age groups positivity rates varied from 15% to 36%. The results demonstrated a linear trend of increasing anti-HBc prevalence with increasing age. Conclusions. Considering the highest rate of anti-HBc positivity being demonstrated in the age range 46-65 years, it could be assumed that a sufficient number of risk factors accumulate over time resulting in greater population susceptibility to HBV infection.
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