Protective Titers Research Articles

Evaluation of hepatitis B vaccination status and immune response among health care workers in a tertiary care hospital in western India

IntroductionHepatitis B virus infection is still an important health problem worldwide. The risk of contracting HBV by health-care workers (HCWs) is higher than that of the general adult population. Seroprotection is defined as anti-HBs level 10mIU/ml or more following a successful three-dose vaccination course. ObjectiveTo find out the hepatitis B vaccination status and test immune response using anti-HBs titer among HCWs. MethodsWe carried out a retrospective observational study of 218 serum samples from vaccinated HCWs tested for anti-HBs ELISA from January 2016 to December 2017. We collected demographic, health, and HBV vaccination details from test requisition forms. ResultsWe found that 195 (89.44%) HCWs had received a complete course of HBV vaccination. 74.87% HCWs showed a protective level (10mIU/ml or more) of antibodies. We noted a statistically significant association between the protective antibody level and the complete course of vaccination (P<0.001). HCWs had protective levels of antibodies even after 25 years post-vaccination. We found a statistically significant decrease in mean antibody titer with duration (in years) of post-primary vaccination (P<0.001). We noted higher seroprotection in females, age group of 21–30 years, and weight range of 51–70kg. ConclusionHepatitis B vaccination coverage is still inadequate even among HCWs. Even with recommended three dose full vaccination, some HCWs have not achieved protective anti-HBs titer, so we have to make testing of anti-HBs compulsory irrespective of the vaccination status. We noted a decrease in mean antibody titer with duration (in years) of post-primary vaccination.

Nanocochleates containing N-Octylglicoside extracted Vibrio cholerae antigens elicited high vibriocidal antibodies titers after intragastric immunization in a mice model

Biological detergents are used in research laboratories, to extract or solubilize proteins from cell membranes. In order to evaluate the ability to extract antigens from the bacterial cell surface of the wild Vibrio cholerae strain C7258 and study their immunogenic potential by forming proteoliposomes and cochleate and preserving their immunogenicity, the non-ionic detergent, n-Octylglucoside (n-OG), and the Zwitterionic detergent (3-cholamidopropyl dimethylammonio 1-propanesulfonate; CHAPS) were tested in concentrations between 5 and 15%. The anionic detergent sodium deoxycholate (DOC) was used as a reference. Electrophoretic, immunochemical and electron microscopy techniques have characterized the extracts and their chromatographic fractions. With CHAPS and n-OG detergents in concentrations between 5 and 15%, a higher yield was obtained in the extraction of proteins and lipopolysaccharides (LPS) and other components from the bacterial surface compared to 10% DOC. When using 10% DOC, 15% CHAPS and n-OG between 5 and 15%, stable proteoliposomes were formed, of average size between 82 and 93 nm in diameter, with known proportions of proteins, LPS and other components. In some of the concentrations, liposomes were formed with almost pure proteins. Some cholera outer membrane proteins like the 17 kDa protein, which corresponds to the mannose-sensitive hemagglutinin (MSHA), which mediates the adhesion to the brush border of the small intestine and the outer membrane protein U (OMPU) were identified with monoclonal antibodies (mAbs) and purified. The fundamental components of liposomes, proteins and LPS, retained their molecular weights, when compared with known standards and by processing programs of electrophoretic profiles and their antigenicity, without alterations due to the extraction procedure, as could be verified by immune identification techniques with monoclonal antibodies in the case of LPS, significant antigens in this pathogen. The main purpose of the present work was to show that a new anticholera vaccine formulation based on cochleates, containing selected protein and LPS fraction extracted by detergents, is able to elicit protective high titers of bactericidal antibodies after intragastric immunization in the mice model. The objective was achieved.

Serosurveillance of rabies antibodies in dogs in Mumbai region by using indirect ELISA

Rabies is a highly fatal viral infection of the central nervous system affecting all warm-blooded animals including humans. To implement the preventive and control measures, it is important to decide the status of anti-rabies antibodies in dogs. Out of 120 serum samples, 47 (39.2 %) serum samples, showed an antibody titre equal to or above the cut off value of 0.5 IU/ml. The maximum number of dogs showed anti-rabies antibody titres equal to or above the cut-off value of 0.5 IU/ml after <1 month pre-exposure to the rabies vaccine. In 15 serum samples of pet dogs, we observed 13 (86.66 %) dogs with protective anti-rabies antibody titre. Statistical analysis suggests that the age of the animal had no significant effect on anti-rabies antibody titre in vaccinated pet dogs. The overall low seroprevalence of anti-rabies antibody in stray dogs indicates their susceptibility to rabies infection and thus posing a risk of rabies to other animals and humans.

Interferon-λ3 Gene Polymorphic Variants, rs4803217 and rs12980275, Responsiveness to HBV Vaccine and Outcome of HBV and HCV Exposure in Hemodialyzed Patients

Background: In non-uremic populations, rs4803217 in the IFNL3 messenger RNA 3’ untranslated region or rs12980275 downstream of IFNL3 is connected with the spontaneous or therapeutic clearance of HCV and HBV, and rs12980275 is correlated with plasma IFN-λ3 levels. Moreover, rs12980275 is associated with the sustained virological response following antiviral therapy of chronic hepatitis C in hemodialysis patients. Objectives: We investigated IFNL3 polymorphisms, rs4803217 and rs12980275, for association with responsiveness to HBV vaccine and natural consequences of HBV and HCV exposure among hemodialyzed individuals. Methods: The capacity to produce protective anti-HBs titers was recognized if they were ≥ 10 IU/L after vaccination or natural exposure. The IFNL3 rs4803217 (G&gt;T) and rs12980275 (A&gt;G) genetic variants were analyzed using a high-resolution melting curve method in 1,337 hemodialysis subjects. Plasma IFN-λ3 was determined in 188 individuals using ELISA. The Kaplan-Meier method was applied for the analysis of survival probability. Results: The tested polymorphisms did not show associations with the capacity to generate protective anti-HBs titers after HBV vaccination or exposition and self-limitation of HBV exposure. Natural HCV clearance was connected with the IFNL3 rs4803217 GG genotype (OR: 3.036, 95% CI: 1.544 - 5.969, P = 0.001) and haplotypes comprising at least two more frequent alleles but without any variant allele of IFNL3/IFNL4 genetic variants (P &lt; 0.05). Plasma IFN-λ3 levels were not directly influenced by IFNL3 rs4803217 and rs12980275, but differed concerning HBV/HCV serum markers (P = 0.00005) and firmly correlated with anti-HBs titers (r = 0.537, P = 4.15E-16). Both tested polymorphisms were not significantly associated with the survival of hemodialysis patients. Conclusions: Genotyping IFNL3 rs4803217 may be advantageous in the prognosis of natural HCV clearance but does not predict the self-limitation of HBV exposure, responsiveness to HBV vaccine, or hemodialysis patients’ mortality.

The dynamics and association of B and T cell receptor repertoires upon antibody response to hepatitis B vaccination in healthy adults

ABSTRACT The Hepatitis B (HB) vaccine is efficacious in preventing hepatitis B virus infection. However, the association between antibody response to the HB vaccine and dynamic immune repertoire changes in different cell subsets remains unclear. Nine healthy participants were administered three doses of HB vaccine following the 0, 1, 6 month schedule. Peripheral CD4+ T, memory B (MB), naïve B (NB), and plasma cells (PCs) were sorted before vaccination and 7 days following each dose. The complementary determining region 3 of T-cell receptor β (TCRβ) chain and B-cell receptor (BCR) heavy chain (IgG, IgM, IgA) repertoires were analyzed by high-throughput sequencing. All nine participants elicited protective antibody titers to the vaccine at the end of immunization. Compared with the baseline, MB cells showed a significant increase in IgG usage and decreased IgM usage and repertoire diversity at the end of vaccination. TCRβ diversity changes were highly correlated with those of the BCR in MB cells in participants with a faster and robust antibody responses. The percentage of shared clonotypes between NB and MB cells, and MB cells and PCs were much higher than that between NB cells and PCs. The more clonotypes sharing the faster and stronger antibody responses were observed after HB vaccination. These results suggest the integral involvement of MB cells in vaccine immunization. Interaction between CD4+ T and MB cells and B cell differentiation may improve antibody response to HB vaccine.

EXPOSURE OF WILD BOAR (SUS SCROFA) TO THE COMMON VAMPIRE BAT AND LACK OF IMMUNE PROTECTION TO RABIES VIRUS IN BRAZILIAN HUNTERS.

Rabies virus is recognized as one of the most fatal zoonotic agents affecting all mammals. Wild boars (Sus scrofa), classified as a large-size exotic invasive species in Brazil with nationwide hunting permitted, may serve as an extra blood source for the common vampire bat (Desmodus rotundus). Our aim was to document wild boar exposure to vampire bats to determine the seroprevalence of rabies virus antibodies in wild boars and to determine the immune status of hunters in southern and central-western Brazilian regions. Serum samples were collected from 80 wild boars and 49 hunters from natural and degraded areas of the Atlantic Forest biome of southern Brazil and in degraded areas of the Cerrado biome of central-western Brazil. The rabies-modified rapid fluorescent focus inhibition test was performed to detect the presence of rabies virus neutralizing antibodies in wild boars and considered seropositive when ≥0.10 IU/mL. The simplified fluorescence inhibition microtest was used for samples from hunters with a titer of ≥0.50 IU/mL and considered indicative of seroconversion. While 11% (9/80) of wild boars had serum titers for rabies exposure (≥0.10 IU/mL), 88% (43/49) of corresponding hunters lacked immune protective titers (<0.50 IU/mL). Wild boars showed serum titers for rabies likely due to contact with contaminated saliva of vampire bats or from infected carcass consumption. Additionally, Brazilian wild boars can be exposed to rabies and may play an important role in the sylvatic rabies cycle by providing a blood supply for vampire bats, highlighting the possibility of direct transmission of rabies virus to hunting dogs and hunters. These findings suggested hunters are a potential risk group for contracting rabies, and the World Health Organization may consider adding this occupation to their recommendations of who should receive the pre-exposure rabies vaccination.

Does methionine enhance immunity in Mycoplasma gallispeticum F strain vaccinated broiler breeder pullets?

This experiment was conducted to assess a protocol combining 20% excess dietary methionine above the modern breeder pullet's requirement and AviPro MGF vaccine in controlling Mycoplasma gallispeticum (MG) infection. In a complete randomized design, a total of 276 6-wk-old breeder pullets, of the Ross 308 strain were allocated into 4 treatments, each with 3 floor pen replicates of 23 birds/pen: 1) nonvaccinated with adequate methionine (NVAM), 2) nonvaccinated with 20% excess methionine (NVEM), 3) Vaccinated with adequate methionine (VAM), 4) Vaccinated with 20% excess methionine (VEM). Vaccination with AviPro MGF at 6 wk of age was performed via drinking water. Results indicated that the rate of depictable growth and tracheal colonization of MGF vaccine strain is 6 wk postvaccination. Sera Elisa titers showed that an 8-wk-postvaccination period was required for the vaccine to stimulate the humoral immunity response against MG. The 20% excess methionine numerically increased the IgG titer against MG in comparison to other groups, yet this increase was not enough to generate protective titer count. Furthermore, the addition of 20% excess methionine above the recommended levels hindered the tracheal colonization rate and log10 values of AviPro MGF vaccine colony forming units from 5.9/mL of tracheal swab suspension in VAM group to 0.82/mL of tracheal swab suspension in VEM group (P ˂ 0.05). In conclusion, the 20% excess methionine above the modern requirements reduced the tracheal colonization of F-strain MG. Further research is needed to confirm the ability of excess dietary methionine to enhance the adaptive and acquired immunity of broiler breeder pullets.

Study of postvaccinal immunity to whooping cough in children with connective tissue dyslasia syndrome

Purpose: to evaluate the effectiveness of post-vaccination immunity against whooping cough in children aged 1 to 17 years with connective tissue dysplasia syndrome in Stavropol.The principal component analysis was used to optimize the interpretation of immunograms in connective tissue dysplasia syndromedepending on protective titers for whooping cough. Analysis by the method of principal components showed that the links of cellular immunity predominate in children with connective tissue dysplasia syndrome with low titers of antibodies to whooping cough.The general variant of the response of the immune system was observed in children with protective titers of antibodies to whooping cough (1: 160—1: 320). In children with connective tissue dysplasia with titres of 1: 640or more antibodies to whooping cough, humoral and cellular immunities are closely interrelated, it is the presence of humoral and cellular immunity that makesit possible to develop a stable immunity to preventable infections.Thus, the method of main components effectively provides accessible information on key immune processes and is promising.

Investigation of protective level of rabies antibodies in vaccinated dogs in Chennai, India.

BackgroundRabies is still endemic in India causing an estimated 20,000 human deaths a year. Free roaming dogs and unvaccinated owned dogs play a major role in the maintenance of the disease. Dog vaccination is the most crucial aspect of rabies prevention and control strategies; therefore vaccine immunogenicity and longevity are important determinants of the efficiency of rabies control efforts.MethodsIn this study at Madras Veterinary College, India, a total of 297 serum samples were collected from owned dogs that were vaccinated against rabies. Data regarding age, gender, breed, neuter status and last date of vaccination were collected at the time of blood collection. The level of rabies virus neutralising antibodies in the sera of these dogs was measured through rapid focus fluorescence inhibition test. The factors associated with protective level of rabies antibodies in vaccinated dogs were investigated through multivariable regression analysis.ResultsThis cross‐sectional investigation shows that only 40% (119/297) of the all the dogs in the study showed presence of protective level of anti‐rabies antibodies, and 40% (72/180) of the dogs vaccinated within the last year showed presence of protective levels of antibodies causing concern about rabies vaccine quality and its impact on rabies control. The study also shows that older and neutered dogs are more likely to have protective titre among vaccinated dogs, while non‐descript breed dogs are less likely to have a protective titre compared to pure breeds.ConclusionIn this study 60% (108/180) of young prima dogs and adult dogs did not show protective levels of antibodies within the year of last rabies vaccination, although they had previous vaccination history. This high percentage of apparent non‐responders is a cause of concern of administration, distribution, storage, potency and quality management of vaccines in India.

Correlates of protection from SARS-CoV-2 infection

Correlates of protection from SARS-CoV-2 infection

Persistence of Anti-Hbs after up to 30 Years in Health Care Workers Vaccinated against Hepatitis B Virus.

The burden of hepatitis B virus (HBV) infection is a serious public health problem all over the world. Vaccination remains the most effective prevention measure, and safe and effective HBV vaccines have been available since 1982. Health care workers (HCWs) vaccinated against HBV and prospectively followed up for at least 14 years were classified by their antibody titers after primary vaccination as: poor responders (10–99 mIU/mL); moderate responders (100–999 mIU/mL); and good responders (≥1000 mIU/mL). The incidence of antibody loss was calculated for 1000 person-years and the anti-HBs persistence was calculated. The analysis concerned 539 HCWs: 494 good responders (91.7%); 37 moderate responders (6.9%); and eight poor responders (1.5%). The incidence of anti-HBs loss was 52.1 per 1000 person-years for the poor responders, 11.3 per 1000 person-years for the moderate responders, and 1.4 per 1000 person-years for the good responders. The mean persistence of anti-HBs differed significantly between the three groups, being: 19.2 years (95% CI: 15.6–22.8), 25.4 years (95% CI: 23.0–27.9), and 31.0 years (95% CI: 30.5–31.5) for the poor, moderate and good responders, respectively. In conclusion, our findings demonstrate a good persistence of protective anti-HBs titers in HCWs exposed to occupational risk for up to 30 years after a primary vaccination cycle (even without a booster dose) if their titer was initially higher than 100 mIU/mL.

Are patients with rheumatic diseases on immunosuppressive therapies protected against preventable infections? A cross-sectional cohort study

ObjectiveTo evaluate the prevalence of infections, prevalence of hospitalisation due to infections, the vaccination status and perceived screening of infections prior to the start of biologic disease modifying antirheumatic drugs...

Circulating Tfh cell and subsets distribution are associated with low\u2010responsiveness to hepatitis B vaccination

BackgroundAn estimated 5–10 % of healthy vaccinees lack adequate antibody response following receipt of a standard three-dose hepatitis B vaccination regimen. The cellular mechanisms responsible for poor immunological responses to hepatitis B vaccine have not been fully elucidated to date.MethodsThere were 61 low responders and 56 hyper responders involved in our study. Peripheral blood samples were mainly collected at D7, D14 and D28 after revaccinated with a further dose of 20 µg of recombinant hepatitis B vaccine.ResultsWe found low responders to the hepatitis B vaccine presented lower frequencies of circulating follicular helper T (cTfh) cells, plasmablasts and a profound skewing away from cTfh2 and cTfh17 cells both toward cTfh1 cells. Importantly, the skewing of Tfh cell subsets correlated with IL-21 and protective antibody titers. Based on the key role of microRNAs involved in Tfh cell differentiation, we revealed miR-19b-1 and miR-92a-1 correlated with the cTfh cell subsets distribution and antibody production.ConclusionsOur findings highlighted a decrease in cTfh cells and specific subset skewing contribute to reduced antibody responses in low responders.

Containment of varicella outbreak in intensive care unit of a tertiary level hospital.

Background:Varicella–Zoster virus (VZV) infection in healthcare organizations, especially in intensive care units (ICU), having admitted immunocompromised patients, is of serious concern as well as poses threat to healthcare workers working in such critical areas. The present report defines the transmission and infection control measures initiated to curtail VZV infection spread in the trauma ICU of a tertiary care hospital of North India.Outbreak Report:At the infection outset, there were 12 patients admitted in ICU and 54 healthcare workers were posted to manage these critical patients. After confirmation of VZV infection, all susceptible patients as well as healthcare workers were quarantined and fresh intake of patients was restricted. Out of the total healthcare workers, 14 (25.92%) were found susceptible (as per protective VZV IgG titers) and were vaccinated. Of the 12 patients admitted in the ICU, six patients were discharged and sent home directly, four patients expired due to their critical disease state, one patient left against medical advice, and one patient remained admitted in ICU till the incubation period was over. Epidemiologically, line listing for index case reporting was done. The efficacy of control measures was re-evaluated to strengthen existing infection control practices and general measures viz. strict hand washing, adherence to aseptic protocols and intensification of environmental cleaning.Conclusions:Established varicella surveillance measures ensure VZV outbreaks are identified in a timely manner and control measures implemented to prevent further transmission. Also, vaccination policy among HCWs is the utmost requirement despite having huge financial implications.

WEST NILE VIRUS SEROCONVERSION IN EASTERN LOGGERHEAD SHRIKE (LANIUS LUDOVICIANUS MIGRANS) AFTER VACCINATION WITH A KILLED VACCINE.

The loggerhead shrike (Lanius ludovicianus migrans) is a migratory songbird that has undergone massive population declines in Ontario since the 1950s. As part of a broad strategy of recovery, a captive breeding population was established in the late 1990s. This species appears to be extremely sensitive to West Nile virus (WNV) infection, with prior outbreaks at Ontario breeding facilities reaching a 100% mortality rate. This study aimed to investigate the humoral response to vaccination in juvenile birds given single versus serial booster vaccinations, as well as to assess the duration of protective virus-neutralizing titers in annually vaccinated adult birds, by measuring WNV-neutralizing antibodies via the Plaque Reduction Neutralization Test. Twenty-two adult birds and forty 18-22-day-old chicks were included in the study. Annual vaccination resulted in serum neutralizing antibody against WNV for only 59% of adult individuals 1 yr following vaccination. These results, coupled with the death of one vaccinated adult individual due to WNV infection, suggest that a second booster vaccination may be required to adequately protect adult individuals throughout the WNV transmission season. The results of the trial involving juvenile birds indicate that vaccination does not effectively stimulate the immune system of naïve juveniles to produce serum-neutralizing antibodies against WNV in the majority of tested birds, although serial booster vaccination appears to provide a level of improved seroconversion. However, the loss of 19% of naïve juveniles to natural WNV infection versus a less than 3% loss of juveniles that received at least one vaccination suggests some level of cell-mediated immunity and protection against infection takes place in juvenile birds postvaccination. The deaths of several nonvaccinated juveniles and one vaccinated adult at this study facility suggest that WNV continues to be a pathogen of high risk in this species in captivity, and likely in the wild as well.

#92: What Is the Optimal Management of Patients Immunosuppressed with the Anti-compliment Monoclonal Antibody, Eculizumab? A Case Report and Review

Abstract Background Patients with deficiencies of terminal components of complement are at hundreds to thousands fold increased risk of severe and fatal Neisseria spp. infections compared with the general population. Eculizumab is a newly approved monoclonal antibody C5 complement inhibitor. It is indicated for the treatment of atypical hemolytic uremic syndrome (atypical HUS), myasthenia gravis, and paroxysmal nocturnal hemoglobinuria. Because of the complement-depleting effect of Eculizumab dosing (Soliris®, Alexion Pharmaceuticals, Munich, Germany), patients are immunosuppressed for specific infectious pathogens (including Neisseria species) against which protection partially relies on normal complement activity. Because Eculizumab treatment is associated with a dramatically increased risk of Neisseria species. infections, recommendations for Neisseria meningitidis vaccination and antibiotic prophylaxis are contained in Eculizumab prescribing information. However, the most appropriate prevention of infections after Eculizumab has yet to be determined. Methods Case report and literature review. Results A previously healthy 7-year-old male was diagnosed with atypical HUS which included renal failure progressing to dialysis, persistent thrombocytopenia, hemolytic anemia, and hemoglobinuria. Stool cultures and a stool multiplex PCR panel did not detect Shiga-like producing E. coli nor E. coli O157/H7. Eculizumab dosing was therefore planned and Infectious Diseases consultation was obtained for appropriate preventions. The FDA Prescribing Information recommends Neisseria meningitidis vaccination before starting Eculizumab or, if immediate Eculizumab is necessary, to use antibiotic prophylaxis until 2 weeks after vaccination. The accepted protective titer after meningococcal vaccination is population based and uses the serum bactericidal assay (SBA). An antibody titer of &amp;gt;1:4 (human compliment) or 1:8 (rabbit complement) is considered protective. However, this “gold standard” assay incorporates the use of exogenous human or rabbit complement. The protective SBA titers in subjects with terminal complement component deficiencies may not be properly assessed using these same SBA titer protective thresholds. Furthermore, serious meningococcal infections have occurred after appropriate vaccination in patients receiving chronic Eculizumab treatments (ie for paroxysmal nocturnal hemoglobinuria). Finally, SBA protective levels after single Neisseria meningitidis vaccination have not been achieved in majorities of patients with renal failure receiving dialysis and or transplant immunosuppression. Conclusions The current Eculizumab prescribing information recommendations for vaccination and antimicrobial prophylaxis may be inadequate to prevent serious Neisseria infections. Repeated Neisseria meningitidis vaccination and extended antibiotic prophylaxis may afford better protection in patients chronically dosed with Eculizumab.

Immunogenicity and safety of anti-SARS-CoV-2 mRNA vaccines in patients with chronic inflammatory conditions and immunosuppressive therapy in a monocentric cohort

IntroductionIn light of the SARS-CoV-2 pandemic, protecting vulnerable groups has become a high priority. Persons at risk of severe disease, for example, those receiving immunosuppressive therapies for chronic inflammatory cdiseases...

Non-neutralizing Antibodies May Contribute to Suppression of SIVmac239 Viremia in Indian Rhesus Macaques

The antiviral properties of broadly neutralizing antibodies against HIV are well-documented but no vaccine is currently able to elicit protective titers of these responses in primates. While current vaccine modalities can readily induce non-neutralizing antibodies against simian immunodeficiency virus (SIV) and HIV, the ability of these responses to restrict lentivirus transmission and replication remains controversial. Here, we investigated the antiviral properties of non-neutralizing antibodies in a group of Indian rhesus macaques (RMs) that were vaccinated with vif, rev, tat, nef, and env, as part of a previous study conducted by our group. These animals manifested rapid and durable control of viral replication to below detection limits shortly after SIVmac239 infection. Although these animals had no serological neutralizing activity against SIVmac239 prior to infection, their pre-challenge titers of Env-binding antibodies correlated with control of viral replication. To assess the contribution of anti-Env humoral immune responses to virologic control in two of these animals, we transiently depleted their circulating antibodies via extracorporeal plasma immunoadsorption and inhibition of IgG recycling through antibody-mediated blockade of the neonatal Fc receptor. These procedures reduced Ig serum concentrations by up to 80% and temporarily induced SIVmac239 replication in these animals. Next, we transferred purified total Ig from the rapid controllers into six vaccinated RMs one day before intrarectal challenge with SIVmac239. Although recipients of the hyperimmune anti-SIV Ig fraction were not protected from infection, their peak and chronic phase viral loads were significantly lower than those in concurrent unvaccinated control animals. Together, our results suggest that non-neutralizing Abs may play a role in the suppression of SIVmac239 viremia.

Immunological Protection of Individuals Aged 3 to 25 Years Against Pertussis: Regional Cross-Sectional Study

Background. Recently, there has been an increase in the incidence of pertussis in unvaccinated, as well as vaccinated children and adults. The major risk group for pertussis are infants and children over 4 years of age due to gradual decrease in basic immunity. Objective. The aim of the study was to analyze postvaccinal immunity against pertussis in individuals aged 3 to 25 years in Krasnodar. Methods. The study was carried out in the period between July 2018 and October 2019 and included patients aged 3 to 25 years with completed (according to National Immunization Schedule) immunization against pertussis with no history of pertussis in the past. Postvaccinal immunity against pertussis in this sample was determined by the ratio of study participants with minimum protective antibodies titer to Bordetella pertussis (≥ 1:160). Results. The minimum protective antibody titer was revealed in 24 out of 76 participants. Distribution to age groups was the following: children aged 3 to 7 years — 2/28 (7%), 8 to 17 years — 13/22 (59%; p &lt; 0.001, compared with the younger age group), ≥ 18 years — 9/26 (35%; p = 0.017). There was no postvaccinal immunity (no antibodies detected) in 6 (21%), 1 (5%) and 4 (15%) participants, respectively. Conclusion. Insufficient postvaccinal (humoral) immunity against pertussis was revealed in majority of children under 7 years. The ratio of such children decreases with age. It suggests the presence of hidden circulation of Bordetella pertussis and, as a result, previous medical condition in erased or abortive form.

ОЦЕНКА ЭФФЕКТИВНОСТИ УНИВЕРСАЛЬНОЙ ВАКЦИНЫ ПРОТИВ ХЛАМИДИО-ЗА СЕЛЬСКОХОЗЯЙСТВЕННЫХ ЖИВОТНЫХ НА КРОЛИКАХ

The article presents data on laboratory tests of a universal vaccine against chlamydia of farm animals for sterility, safety, antigenic activity and immunogenicity. The sterility of the new vaccine preparation was evaluated on nutrient media (MPA, MPB, MPPB and Saburo), the vaccine was harmless according to the results of bioassays on laboratory white mice and guinea pigs. The vaccine was found to be sterile and harmless to laboratory animals. Evaluation of antigenic activity was car-ried out on rabbits, the study lasted 195 days, the results were taken into account on the basis of data obtained during systematic serological studies of blood serum immunized with rabbits. It was found that the vaccine stimulates the immune system of laboratory animals to produce complemen-tary chlamydial antibodies. After 6.5 months after the administration of the drug, the titers of chla-mydial antibodies remained above the protective titer and were equal on average 1:60. Evaluation of the immunogenicity of the vaccine was carried out in an acute experiment on rabbits (females). Dur-ing the experiment, it was possible to establish the ability of the vaccine to induce the production of immunity in laboratory animals that can overcome chlamydial infection. Healthy rabbits were ob-tained from rabbits vaccinated and infected at the 3rd week of pregnancy, while mass abortions, stillbirths and the birth of non-viable offspring were noted in the control groups. According to the results of post-mortem dissection of animals from the experimental and control groups, it was found that vaccinated and further infected animals did not reveal any pathological changes in the internal organs, in contrast to the animals from the control groups.