Protective Titers Research Articles

Pneumococcal Serotype-Specific Antibodies in Children with Recurrent Oto-sinopulmonary Infections.

Low titers to pneumococcal vaccine are a frequent finding in pediatric patients with recurrent oto-sinopulmonary infections. To characterize the pre- and post-immunization antibody trend for each serotype included in the pneumococcal 13-valent conjugate vaccine (PCV13), in a cohort of pediatric patients with recurrent oto-sinopulmonary infections. This retrospective review identified 182 patients with recurrent oto-sinopulmonary infections (131 required an immune workup and 99 had low pneumococcal titers leading to a PCV13 vaccine booster). Baseline pneumococcal serotype-specific antibody titers at initial visit and 6 weeks after the vaccine booster were obtained. An adequate response to the pneumococcal conjugate vaccine was deemed to be a 4-fold increase over baseline and/or a post-immunization titer of 1.3 µg/ml or greater. Overall, PCV13 booster provided a significant improvement in the number of protective titers, increasing from 3.6 serotypes at baseline to 11.1 serotypes at 6 weeks (p < 0.001). This increase correlated with improved clinical outcomes (81% showed no signs of recurrent infection after the first booster and 94% after a second booster). Post-immunization antibody concentrations were significantly higher than at baseline for all serotypes (p< 0.05) and only 8, 9N, and 12F did not exhibit a greater than 4-fold increase (p> 0.05) 6 weeks following booster. There were no differences between patients at different ages in post-immunization titer levels for all serotypes. In pediatric patients with recurrent oto-sinopulmonary infections, an additional pneumococcal booster proved to be effective in the protection of these children against further infections, across all age groups.

Factors predicting the level of vaccine protection against hepatitis B virus infection among physicians and nurses in Šabac, Serbia.

As healthcare workers run a high and constant occupational risk of hepatitis B virus (HBV) infection through exposure to biological material, vaccination is mandatory as well as the monitoring of antibody levels one to two months after complete immunisation. The aim of this descriptive cross-sectional study was to determine HBV vaccine coverage of 200 primary and secondary healthcare workers (100 each) from Šabac, Serbia and their blood anti-HBs titre. We also wanted to identify factors that could predict the titre. Anti-HBV vaccination covered all participants, of whom 89.5 % were fully vaccinated, and 85 % had a protective antibody titre. We found a statistically significant association between antibody titre and the number of received vaccine doses, chronic jaundice, autoimmune disease, and cancer in our participants. The fact that 15 % did not achieve the protective antibody titre confirms the necessity of its control after immunisation, which is not routinely carried out in most countries, Serbia included. It is, therefore, necessary to develop a detailed strategy for monitoring vaccination and serological status of healthcare workers in order to improve their safety at work. An important role should also be given to continuous education of healthcare workers from the beginning of schooling to the end of their professional career.

Preclinical Evidence for the Protective Capacity of Antibodies Induced by Lyme Vaccine Candidate VLA15 in People.

Vaccine candidate VLA15 is designed to protect against the dominant Borrelia genospecies-causing Lyme disease in North America and Europe. Active immunization with VLA15 has protected in the mouse model of tick challenge. VLA15 is currently under evaluation in clinical studies for the prevention of Lyme borreliosis. Mice were passively administered sera from clinical trial participants vaccinated with VLA15, or normal human serum from unvaccinated individuals as control. Posttransfer serum anti-outer surface protein A (OspA) immunoglobulin G titers were assessed by enzyme-linked immunosorbent assay. Following passive transfer, mice were challenged with Ixodes ticks colonized with Borrelia burgdorferi (OspA serotype 1) or Borrelia afzelii (OspA serotype 2) and infection was determined by serology for VlsE C6 or by polymerase chain reaction and culture to assess the presence of Borrelia bacteria. Passive transfer of immune sera prevented transmission of Borrelia from the tick vector and protected mice against challenge. Posttransfer protective threshold immunoglobulin G antibody titers were observed in this animal model of 131 U/mL for B burgdorferi (OspA serotype 1) and 352 U/mL for B afzelii (serotype 2). Passive transfer of sera from trial participants immunized with VLA15 protected mice from borreliosis in a tick challenge model. This indicates that VLA15 induces functional immune responses in people that can be linked to efficacy in a stringent preclinical model.

Minimal Protective Antibody Titers Elicited in Sheep by RVFV MP-12 and arMP-12ΔNSm21/384 Vaccine Candidates

The live attenuated Rift Valley Fever Virus (RVFV) vaccine candidates, RVFV MP-12, and the recombinant derivative, RVFV arMP-12ΔNSm21/384 (MP-12NSm-del), are among the most promising next-generation domestic ruminant vaccine candidates. While both vaccines consistently elicit protective neutralizing Antibodies (nAb) in domestic ruminants, the minimal protective antibody titer is unknown. Therefore, we conducted studies to determine the minimal protective nAb titers elicited in sheep by these vaccines using a mouse model. The approach involved the transfer of sera obtained from sheep vaccinated with the MP-12 and MP-12NSm-del vaccines to 6- to 8-week-old BALB/c mice. The sheep nAb titers ranged from 20 to 640 at the time of transfer. A blood sample was obtained from each mouse 24 hours post-transfer to determine the nAb titer 2 hours before challenging each animal with a lethal dose of virulent RVFV (strain ZH501). All challenged mice were observed daily for 21 days for morbidity and mortality. The lowest nAb titer that protected the animals was interpreted as an estimate of the minimal protective efficacy of the vaccine. The results indicated that nAb titers as low as 10 to 20 elicited by the MP-12 and MP-12NSm-del vaccine candidates in sheep 10 days post-vaccination afforded protection to the mice. However, the nAbs elicited in one sheep by MP-12 before day 10 post-vaccination and ranging in titer from &lt; 5 to 40 only afforded protection to 3 out of 18 mice, and therefore suggested that innate and/or the cellular immune response were also needed for protection during early RVFV infection. The findings further support these RVFV candidate vaccines as potential veterinary vaccines for domestic ruminants and offer a promising BALB/c mouse RVFV challenge model as a surrogate for evaluating the protective nAb response elicited by RVFV vaccines.

Identificación de genogrupos de protoparvovirus y sus variantes en leucocitos de gatos domésticos del Valle Central de Costa Rica

Carnivore protoparvovirus 1 (CPPV-1) includes feline parvovirus (or feline panleukopenia virus, FPV) and canine parvovirus 2 (CPV-2). Currently, although CPV-2 is not found in nature, its variants CPV-2a, CPV-2b, and CPV-2c are found and can infect cats as well. The objective of this research was to identify CPPV-1 and its variants as antibodies against CPPV-1 in the blood of domestic cats from the Central Valley of Costa Rica. Blood samples were collected from 155 cats, along with the following data: sex, age, breed, vaccination information, the environment where the animal lives (urban or rural), coexistence with other cats, health status, any chronic diseases, lifestyle (indoor or outdoor cat), and place of origin. Blood samples were analyzed by hemagglutination inhibition assay (HIA) and molecular techniques (polymerase chain reaction (PCR) and sequencing). Antibodies against CPPV-1 were detected using HIA in all cats; a total of 112 (72.3%) had protective titers (≥1:80). Using real-time PCR, CPPV-1 was detected in the blood of 42 (27.1%) cats, none of which presented anemia, leukopenia, or any chronic disease; five (11.9%) were vaccinated, and three (7.1%) had low body condition but showed appetite and had no other symptom or sign associated with CPPV-1. The group of qPCR-positive cats did not show significant differences compared to the qPCR-negative group regarding age, sex, lifestyle, coexistence with other cats, and antibody titers. Ten asymptomatic and healthy cats showed FPV (n=2) and CPV-2c (n=8) in blood with nucleotide similarities of 100% (GenBank M38246) and 99.8%-100% (GenBank AF401519), respectively.

Low risk of hepatitis B virus reactivation in membranous nephropathy patients with resolved infection undergoing rituximab-based regimens without antiviral prophylaxis

IntroductionPatients with resolved hepatitis B virus infection undergoing rituximab are at risk of hepatitis B virus reactivation without antiviral prophylaxis. However, the risk in such patients treated with rituximab-based regimens for membranous nephropathy is not clear. We evaluated the risk of hepatitis B virus reactivation in membranous nephropathy patients with resolved infection undergoing rituximab-based regimens without antiviral prophylaxis. MethodsClinical data of 51 membranous nephropathy patients with resolved hepatitis B virus infection undergoing rituximab-based regimens without antiviral prophylaxis were retrospectively analyzed. Among these, 21 patients were followed for more than 1 year after rituximab discontinuation. The clinical data collected aimed to assess patients’ responses and the risk of hepatitis B virus reactivation during and after rituximab treatment. Results30/51 (58.8 %) patients reached complete or partial remission at 12 months. None of the patients experienced HBsAg seroreversion during rituximab treatment. Alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase and total bilirubin levels, as well as the numbers of patients who exceeded the upper limits of normal for alkaline phosphatase and prothrombin time, did not show any statistically significant difference during rituximab-based therapy. Neither did the anti-HBs level, the number of patients with protective anti-HBs titers exceeding 10 U/L, nor the levels of CD19+ B cells, CD4+ T cells, CD8+ T cells, and natural killer cells. Among the 21 patients followed for 12 (ranging from 12 to 19) months after rituximab discontinuation, no hepatitis B virus reactivation was observed. The mean anti-HBs level and the number of patients with anti-HBs titers over 10 U/L did not show any statistically significant difference during the extended follow-up of 33 patient-years. Neither did the CD4+ T cell, CD8+ T cell, nor the natural killer cell counts. One patient presented with an ALT level that exceeded the baseline value by three times and reached above 100 U/L, accompanied by elevations in AST, GGT, and ALP levels. Meanwhile, the anti-HBs titer was 816.09 U/L, and HBsAg was negative. ConclusionThe administration of rituximab-based regimens in membranous nephropathy patients with hepatitis B virus resolved infection leads to a low risk of hepatitis B virus reactivation without antiviral prophylaxis. Patient’s immune status, drug combination, rituximab strategy should be fully evaluated when considering antiviral prophylaxis therapy.

Immunogenicity of a novel inactivated canine adenovirus type 2 variant vaccine for dogs.

The immunogenicity of vaccines containing the canine adenovirus (CAdV) type 2 (CAdV-2) variant has not yet been reported. We prepared a novel inactivated CAdV-2 variant vaccine using the CAV2232-41 strain, and evaluated its safety and immunogenicity in raccoon dogs. The growth kinetics of CAV2232-41 were determined using Madin-Darby Canine Kidney (MDCK) cells. The nucleotide sequences of CAV2232 and CAV2232-41 were determined by next-generation sequencing. To generate the CAdV-2 variant vaccine, CAV2232-41 propagated in the MDCK cells was inactivated with 0.1% formaldehyde. Two vaccines were prepared by blending inactivated CAV2232-41 with Cabopol and Rehydragel adjuvants. Safety and immunogenicity of the CAV2232C and CAV2232R vaccines were evaluated in guinea pigs. Safety and immunogenicity of the CAV2232C vaccine were also evaluated in raccoon dogs. The virus neutralizing antibody (VNA) titer against CAV2232-41 was measured in sera collected from immunized guinea pigs and raccoon dogs. CAV2232-41 showed the highest viral titer on days 4-6 post-inoculation and had a deletion in the E3 gene, which was confirmed as a CAdV-2 variant. Guinea pigs inoculated with CAV2232C showed slightly higher VNA titers than those inoculated with CAV2232R 2 weeks after booster vaccination. Raccoon dogs immunized with the CAV2232C vaccine developed high mean VNA titers, while non-vaccinated raccoon dogs were antibody-negative. The CAV2232C vaccine is safe and induces a protective VNA titer in raccoon dogs.

Measuring Immunoglobulin Titers Among Healthcare Workers After Hepatitis B Vaccination: A Cross-Sectional Study in Kuwait.

Introduction Hepatitis B virus (HBV) is a highly infectious disease affecting the liver, causing life-threatening acute and chronic hepatitis. It poses a significant global public health burden and is a major occupational risk for healthcare workers (HCWs) due to transmission through blood and blood products. Given their increased risk compared to the general population, vaccination is crucial in limiting the spread of HBV and protecting HCWs. This study aims to measure the anti-HBs titers of HCWs in the Farwaniyah Health District in Kuwait after completing three doses of the HBV vaccine. Methods This cross-sectional study was conducted in the Farwaniyah Health District of Kuwait between May and July 2023. We collected data from 556 participants from various departments, including physicians, nurses, and laboratory technicians, chosen through simple random sampling. Inclusion criteria included the completion of three doses of the HBV vaccine (Engerix-B recombinant vaccine, GlaxoSmithKline Biologicals, Brentford, UK). Demographic data were collected, and blood samples were tested for hepatitis B surface antigen antibody titers using fourth-generation enzyme-linked immunosorbent assay. Participants were categorized based on sex, age, specialty, and time since the last vaccine dose. The chi-square test and Fisher's exact test assessed differences in categorical variables, with a p-value of <0.05 considered statistically significant. Results The study included 556 participants, with 304 (54.7%) women and 252 (45.3%) men. Participants were assigned into two age groups: 294 (52.9%) were 18 to 40 years oldand the remainder (262) were over 40. Most participants were nursing staff (n=392; 70.5%), followed by physicians (n=110; 19.7%) and technicians (n=54; 9.7%). A high proportion (n=340; 61.2%) received their last vaccine dose within the last five years. Overall, 375 (67.4%) HCWs developed sufficient anti-HBs titers of ≥100 mIU/mLwhile 181 (32.6%) had levels below 100 mIU/mL. Age between 18 and 40 years and receiving the vaccine within the last five years were significantly associated with protective titer levels, while sex was not. Nurses had significantly higher immunity levels compared to doctors and technicians. Conclusions HCWs in the Farwaniyah area of Kuwait generally responded positively to the HBV vaccine. Younger HCWs and those who received the vaccine more recently were more likely to have a protective immune response. Nurses demonstrated higher rates of seroconversion compared to doctors and technicians. These results suggest that HBV vaccination programs should prioritize timely booster doses, especially for older HCWs and those vaccinated longago. Monitoring antibody levels is crucial to ensure ongoing protection, particularly in high-risk groups such as nurses. Implementing these measures can enhance the effectiveness of HBV vaccination programs, reduce HBV incidence among HCWs, and contribute to a safer healthcare environment. Post-vaccination testing is essential to ensure the safety of all HCWs against HBV.

HEPATITIS B VACCINATION STATUS AMONG A TARGET GROUP BORN IN 1992-2000: A STUDY FROM BULGARIA

The purpose of this study is to determine the prevalence of stress among students of various health Hepatitis B virus (HBV) infection is a significant cause of morbidity and mortality and a leading cause of chronic liver disease. Vaccination has a key role in hepatitis B prevention. Compulsory immunization for all healthy newborns was introduced in Bulgaria in 1992 as part of the WHO global strategy. Purpose: The aim of this study was to determine the extent of post-vaccination seroprotection among persons born in 1992 – 2000 who received recombinant hepatitis B vaccine. Material/methods: A total of 923 serum samples of a target group of vaccinated individuals (412 males and 511 females) at a mean age of 23.0±2.7 years were tested over a two-year period (2018-2019). The quantitative analysis of hepatitis B surface antibodies (anti-HBs) levels was performed by CLIA using a LIAISON® anti-HBs II quantitative diagnostic kit (Dia Sorin, Italy). Results: All 923 individuals included in the study were hepatitis B surface antigen (HBsAg) negative. Protective anti-HBs titers ranging from 11 to &gt;1000 mIU/mL were found in 45.3% of them. The sex distribution of the tested subjects varied significantly between years (p=0.023). The difference in protective anti-HBs levels between the two sexes was non-significant (p&gt;0.05). There was a weak negative correlation between year of birth and anti-HBs titer (Pearson's r=0.351, p&lt;0.001). Conclusions: The results of this large study conducted among subjects immunized against hepatitis B in childhood showed varying levels of post-vaccination seroprotection. On average, 23 years after universal immunization, 54.7% of the study cohort had no protective levels of anti-HBs (negative or equivocal result).

Vaccination against Measles in Patients with Oncological Disease

Relevance. Growing distrust of vaccines around the world, a decrease in vaccination rates have led to an increase in the incidence of measles and a rise in the vulnerability of people with immunodeficiency status. The aim. To study the efficacy and safety of measles vaccination in children with oncohematological diseases. Materials &amp; methods. The study involved 107 children: 74 of them with a history of acute lymphoblastic leukemia and 33 with solid tumors. All children had a history of receiving standardized polychemotherapy. In all the subjects, the vaccination history was studied, the titers of specific antibodies to measles were determined. Children with non-protective levels of antibodies (53 children) were subsequently vaccinated against measles. Results and discussions. Of the 107 children examined, before cancer, 99 (92.5%) were vaccinated against measles, of which 68 (68.7%) patients were only vaccinated, and 31 (31.3%) had vaccination and revaccination. Protective titers of antibodies against measles were preserved in 51 people (51.5%), and 48 (48.5%) were seronegative. When assessing immunogenicity on days 14, 45 after the introduction of the vaccine, it turned out that by day 14, 27 out of 53 children (50.9%) developed measles antibodies, and by day 45, 33 out of 53 children (62.3%), the rest of the children did not developed a protective level of antibodies, including 3 of 6 revaccinated. Conclusion. Thus, children with malignant diseases, regardless of the number of previous vaccinations and the duration of the end of therapy, become unprotected or have low titers of antibodies to measles in 83.8%, and immunization after treatment is effective in 62.3% of cases.

Serosusceptibility and hesitancy for booster HBV vaccination among health care workers in Italy: A cross-sectional study

BackgroundHealth care workers (HCWs) are at increased risk of exposure to hepatitis B virus (HBV). The most effective prevention measure is vaccination, with a serum hepatitis B surface antibody (HBsAb) titre > 10 mIU/ml considered protective. To date, the sociodemographic and occupational characteristics related to HBV serosusceptibility and factors associated with booster hesitancy remain unclear. Therefore, this study aimed to identify factors associated with maintaining a protective HBsAb titre in a large sample of HCWs and to evaluate factors potentially associated with hesitancy towards vaccine boosters. MethodsA cross-sectional study was conducted among HCWs who underwent a health surveillance visit between 2017 and 2022. If the serum HBsAb titre was < 10 MIU/ml, a vaccine booster dose was offered. Based on their willingness to be vaccinated, employees were classified into three groups: acceptance, hesitation, and refusal. Uni- and multivariable analyses were performed to assess the association of demographic and occupational characteristics with serosusceptibility and attitudes towards vaccination. ResultsA total of 1632 (27%) employees were shown to be nonimmune. A lower median age and being a physician were significantly associated with a protective HBsAb titre. A total of 706 nonimmune employees (43.3%) accepted the vaccination, 865 (53%) hesitated, and 61 (3.7%) refused. The median age of those who refused vaccination was significantly higher than that of those who hesitated and those who were vaccinated. Acceptance of vaccination was significantly higher among nurses, while nurse aides hesitated more; among nonmedical graduate staff both hesitation and refusal were higher than expected. In the multivariable analysis, higher age, female sex, and employment as an allied health care professional were shown to be significantly associated with hesitation/refusal, while being born abroad turned out to be protective. ConclusionsOur study showed that approximately a quarter of HCWs were not immune to HBV infection, and of these, more than half were hesitant towards or refused the booster dose. The risk of hesitation/refusal was higher with age in women and among allied health care staff. Based on these findings, further studies are needed to prospectively evaluate HBV seroprevalence, vaccination adherence, factors associated with hesitancy, and the effectiveness of health surveillance strategies in a high-risk population susceptible to infection.

Effects of astragalus extract, levamisole and ascorbic acid on humoral immunity in chickens vaccinated with newcastle disease vaccines

This study was designed to assess the effects of Astragalus extract, levamisole and ascorbic acid on the humoral immune response of chickens vaccinated with live and inactivated Newcastle Disease (ND) vaccines. Sixty day-old Cobb500 broiler chicks were used for the study. At day old, the maternally derived antibodies (MDA) to ND virus was determined and the chicks were then housed in a bio-secured pen with water and feed given ad-lib. On the sixth day, the MDA decay was determined thereafter, the chicks were shared into 4 treatment groups. Group A (Astragalus extract); Group B (levamisole); Group C (ascorbic acid) and Group D (Control) of 15 chicks each. Response to ND vaccinations was determined through bleeding to obtain sera for haemagglutination inhibition test at 7 and 14 days except for the second booster with inactivated Komarov vaccine where it was done at 7, 14 and 21 days post vaccination respectively. Antibody titres in the chicks 7 days post first dose of vaccination with La Sota was high in all the treatment groups above the control with 100 % of the chicks having protective antibody titre of ≥4 log2 until day 30 when the antibody titres in all the groups dropped drastically following the second dose of live La Sota vaccination as the first booster vaccine. However, following the second booster with inactivated Komarov the antibody titres increased in all the treatment groups in comparison to the control especially in groups B and C with GMTs of 5.8 ± 0.19 log2 and 6.1 ± 0.27 log2 respectively. We observed that ascorbic acid and Levamisole may have humoral immuno-stimulating effects on vaccinated chickens through yet to be fully explored mechanism. It is recommended that ascorbic acid or levamisole could be used during vaccinations as immuno-stimulating agents to enhance humoral antibody response in vaccinated flocks.

Antigenic drift and immunity gap explain reduction in protective responses against influenza A(H1N1)pdm09 and A(H3N2) viruses during the COVID-19 pandemic: a cross-sectional study of human sera collected in 2019, 2021, 2022, and 2023

BackgroundNon-pharmaceutical interventions implemented during the COVID-19 pandemic resulted in a marked reduction in influenza infections globally. The absence of influenza has raised concerns of waning immunity, and potentially more severe influenza seasons after the pandemic.MethodsTo evaluate immunity towards influenza post-COVID-19 pandemic we have assessed influenza A epidemics in Norway from October 2016 to June 2023 and measured antibodies against circulating strains of influenza A(H1N1)pdm09 and A(H3N2) in different age groups by hemagglutination inhibition (HAI) assays in a total of 3364 serum samples collected in 2019, 2021, 2022 and 2023.ResultsInfluenza epidemics in Norway from October 2016 until June 2023 were predominately influenza As, with a mixture of A(H1N1)pdm09 and A(H3N2) subtype predominance. We did not observe higher numbers of infections during the influenza epidemics following the COVID-19 pandemic than in pre-COVID-19 seasons. Frequencies of protective HAI titers against A(H1N1)pdm09 and A(H3N2) viruses were reduced in sera collected in 2021 and 2022, compared to sera collected in 2019. The reduction could, however, largely be explained by antigenic drift of new virus strains, as protective HAI titers remained stable against the same strain from one season to the next. However, we observed the development of an immunity gap in the youngest children during the pandemic which resulted in a prominent reduction in HAI titers against A(H1N1)pdm09 in 2021 and 2022. The immunity gap was partially closed in sera collected in 2023 following the A(H1N1)pdm09-dominated influenza seasons of 2022/2023. During the 2022/2023 epidemic, drift variants of A(H1N1)pdm09 belonging to the 5a.2a.1 clade emerged, and pre-season HAI titers were significantly lower against this clade compared to the ancestral 5a.2 clade.ConclusionThe observed reduction in protective antibodies against A(H1N1)pdm09 and A(H3N2) viruses post COVID-19 is best explained by antigenic drift of emerging viruses, and not waning of antibody responses in the general population. However, the absence of influenza during the pandemic resulted in an immunity gap in the youngest children. While this immunity gap was partially closed following the 2022/2023 influenza season, children with elevated risk of severe infection should be prioritized for vaccination.

Dosing of Convalescent Plasma and Hyperimmune Anti-SARS-CoV-2 Immunoglobulins: A Phase I/II Dose-Finding Study.

During the COVID-19 pandemic, trials on convalescent plasma (ConvP) were performed without preceding dose-finding studies. This study aimed to assess potential protective dosing regimens by constructing a population pharmacokinetic (popPK) model describing anti-SARS-CoV-2 antibody titers following the administration of ConvP or hyperimmune globulins (COVIg). Immunocompromised patients, testing negative for anti-SARS-CoV-2 spike antibodies despite vaccination, received a range of anti-SARS-CoV-2 antibodies in the form of COVIg or ConvP infusion. The popPK analysis was performed using NONMEM v7.4. Monte Carlo simulations were performed to assess potential COVIg and ConvP dosing regimens for prevention of COVID-19. Forty-four patients were enrolled, and data from 42 were used for constructing the popPK model. A two-compartment elimination model with mixed residual error best described the Nab-titers after administration. Inter-individual variation was associated to CL (44.3%), V1 (27.3%), and V2 (29.2%). Lean body weight and type of treatment (ConvP/COVIg) were associated with V1 and V2, respectively. Median elimination half-life was 20 days (interquartile range: 17-25days). Simulations demonstrated that even monthly infusions of 600mL of the ConvP or COVIg used in this trial would not achieve potentially protective serum antibody titers for >90% of the time. However, as a result of hybrid immunity and/or repeated vaccination, plasma donors with extremely high antibody titers are now readily available, and a >90% target attainment should be possible. The results of this study may inform future intervention studies on the prophylactic and therapeutic use of antiviral antibodies in the form of ConvP or COVIg. NL9379 (The Netherlands Trial Register).

Seroprevalence to Hepatitis B Virus among Prisoners Taking into Account Age, HIV Status, and Injection Drug Use

Relevance. Prisoners have a high risk of contracting hemocontact viral infections (including HIV, viral hepatitis B and C, etc.), which creates an additional infectious burden on the entire population living in the territory. Aims. To study the level of immune protection to viral hepatitis B in risk groups (age, HIV status, and injection drug use) of persons held in places of detention to identify those in need of vaccine prophylaxis. Materials &amp; Methods. 343 blood serum samples obtained in 2021 from males with negative HBsAg status were studied. Anti-HBs antibodies to HBsAg were determined using a set of reagents “VectoHBsAg-antibodies” (Vector-Best, Russia). Results and discussion. The protective titer of anti-HBs antibodies was detected in 44.0% (n = 151) of cases, and was absent in 56.0% of the subjects. At the same time, anti-HBs was significantly more often detected in people living with HIV/AIDS (p = 0.038), injecting drug users (p = 0.002), as well as young people born after 1984 (p = 0.019). Conclusion. The lack of a significant level of collective immunity among prisoners, primarily the older age group before 1984, their risky behaviors (sexual, injection) indicate the need for active identification of seronegative persons serving sentences in places of detention and specific immunoprophylaxis.

Poliovirus-Neutralizing Antibody Seroprevalence and Vaccine Habits in a Vaccine-Derived Poliovirus Outbreak Region in the Democratic Republic of Congo in 2018: The Impact on the Global Eradication Initiative.

Despite the successes in wild-type polio eradication, poor vaccine coverage in the DRC has led to the occurrence of circulating vaccine-derived poliovirus outbreaks. This cross-sectional population-based survey provides an update to previous poliovirus-neutralizing antibody seroprevalence studies in the DRC and quantifies risk factors for under-immunization and parental knowledge that guide vaccine decision making. Among the 964 children between 6 and 35 months in our survey, 43.8% (95% CI: 40.6-47.0%), 41.1% (38.0-44.2%), and 38.0% (34.9-41.0%) had protective neutralizing titers to polio types 1, 2, and 3, respectively. We found that 60.7% of parents reported knowing about polio, yet 25.6% reported knowing how it spreads. Our data supported the conclusion that polio outreach efforts were successfully connecting with communities-79.4% of participants had someone come to their home with information about polio, and 88.5% had heard of a polio vaccination campaign. Additionally, the odds of seroreactivity to only serotype 2 were far greater in health zones that had a history of supplementary immunization activities (SIAs) compared to health zones that did not. While SIAs may be reaching under-vaccinated communities as a whole, these results are a continuation of the downward trend of seroprevalence rates in this region.

Canine parvovirus type 2 (CPV-2) serological and molecular patterns in dogs with viral gastroenteritis from southern Brazil.

Canine Parvovirus type 2 (CPV-2) is a highly contagious virus that can cause severe systemic disease with gastroenteric symptoms in dogs, particularly in young puppies. Originating from the feline parvovirus in the late 1970s, it swiftly propagated globally, instigating a pandemic in dogs. Despite vaccination advancements, CPV-2 remains a substantial challenge for veterinary professionals and pet owners. This study aimed to contribute knowledge about the current situation of CPV-2 among dogs in southern Brazil. In this study, the sera of 125 dogs (mostly with gastroenteritis symptoms) were screened for antibodies against CPV-2 and their faeces for the virus itself. The results showed that 40% (50/125) of dogs were infected with CPV-2. Most animals (65.5%) had previously been exposed to CPV-2 (with serotitres equal or above 1:40), and only 37.6% had protective antibody titres equal or above 1:80. The findings have also demonstrated that vaccination against CPV-2 significantly reduced the risk of infection, with positive cases decreasing from 56.9% (unvaccinated) to 2.0% (fully vaccinated). Furthermore, the prevalence of CPV-2 decreased as dogs aged, with younger dogs and those with an incomplete or non-existent vaccination history at the highest risk of infection. In conclusion, this study provides valuable insight into the prevalence and risk factors associated with CPV-2 infection in dogs in southern Brazil, thereby providing valuable knowledge for the improvement of veterinary care and pet health.

Safety, tolerability and immunogenicity of PRV-101, a multivalent vaccine targeting coxsackie B viruses (CVBs) associated with type 1 diabetes: a double-blind randomised placebo-controlled Phase I trial

Aims/hypothesisInfection with coxsackie B viruses (CVBs) can cause diseases ranging from mild common cold-type symptoms to severe life-threatening conditions. CVB infections are considered to be prime candidates for environmental triggers of type 1 diabetes. This, together with the significant disease burden of acute CVB infections and their association with chronic diseases other than diabetes, has prompted the development of human CVB vaccines. The current study evaluated the safety and immunogenicity of the first human vaccine designed against CVBs associated with type 1 diabetes in a double-blind randomised placebo-controlled Phase I trial.MethodsThe main eligibility criteria for participants were good general health, age between 18 and 45 years, provision of written informed consent and willingness to comply with all trial procedures. Treatment allocation (PRV-101 or placebo) was based on a computer-generated randomisation schedule and people assessing the outcomes were masked to group assignment. In total, 32 participants (17 men, 15 women) aged 18–44 years were randomised to receive a low (n=12) or high (n=12) dose of a multivalent, formalin-inactivated vaccine including CVB serotypes 1–5 (PRV-101), or placebo (n=8), given by intramuscular injections at weeks 0, 4 and 8 at a single study site in Finland. The participants were followed for another 24 weeks. Safety and tolerability were the primary endpoints. Anti-CVB IgG and virus-neutralising titres were analysed using an ELISA and neutralising plaque reduction assays, respectively.ResultsAmong the 32 participants (low dose, n=12; high dose, n=12; placebo, n=8) no serious adverse events or adverse events leading to study treatment discontinuation were observed. Treatment-emergent adverse events considered to be related to the study drug occurred in 37.5% of the participants in the placebo group and 62.5% in the PRV-101 group (injection site pain, headache, injection site discomfort and injection site pruritus being most common). PRV-101 induced dose-dependent neutralising antibody responses against all five CVB serotypes included in the vaccine in both the high- and low-dose groups. Protective titres ≥8 against all five serotypes were seen in >90% of participants over the entire follow-up period.Conclusions/interpretationThe results indicate that the tested multivalent CVB vaccine is well tolerated and immunogenic, supporting its further clinical development.Trial registrationClinicalTrials.gov NCT04690426.FundingThis trial was funded by Provention Bio, a Sanofi company.Graphical

Immune reconstitution, vaccine responses, and rituximab use after ex-vivo CD34-selected myeloablative allogenic hematopoietic cell transplantation.

Myeloablative T cell depleted (CD34-selected) hematopoietic cell transplantation (HCT) is associated with less acute and chronic graft versus host disease (GVHD). We aimed to examine vaccine responses in relation to immune reconstitution and post HCT rituximab administration in this population. This single center retrospective study included 251 patients with hematological malignancies who received a first CD34-selected HCT between 2012 and 2015. Of 251 patients, 190 were alive 1 year after HCT. Among the entire population, 77 (30.7%) patients were vaccinated. After vaccine administration, 35/44 (80%), 30/75 (40%), 27/36 (75%), 33/65 (51%), 34/51 (51%), 22/28 (79%) and 20/34 (59%) of evaluable patients had protective antibody titers for haemophilus influenzae type B (Hib), Pneumococcus, Tetanus, Diphtheria, Pertussis, hepatitis A (HAV), and hepatitis B (HBV) respectively. Responders to the pneumococcal vaccine had a higher CD45RA T cell count than non responders, with 12/18 patients (66.7%) vs 11/32 (34.4%) p = 0.04. For pneumococcal vaccine, there was also a trend to higher total lymphocyte B cell count in responders vs non responders p = 0.06. Rituximab post HCT was given to 59/251 (23.5%) patients. No difference was found in immune reconstitution patterns for rituximab use between vaccine responders and not. Recipients of CD34-selected HCT may respond to vaccination, and T and B cell subsets could be useful to predict vaccine response.

Antibodies targeting the fusion peptide on the HIV envelope provide protection to rhesus macaques against mucosal SHIV challenge.

The fusion peptide (FP) on the HIV-1 envelope (Env) trimer can be targeted by broadly neutralizing antibodies (bNAbs). Here, we evaluated the ability of a human FP-directed bNAb, VRC34.01, along with two vaccine-elicited anti-FP rhesus macaque mAbs, DFPH-a.15 and DF1W-a.01, to protect against simian-HIV (SHIV)BG505 challenge. VRC34.01 neutralized SHIVBG505 with a 50% inhibitory concentration (IC50) of 0.58 μg/ml, whereas DF1W-a.01 and DFPH-a.15 were 4- or 30-fold less potent, respectively. VRC34.01 was infused into four rhesus macaques at a dose of 10 mg/kg and four rhesus macaques at a dose of 2.5 mg/kg. The animals were intrarectally challenged 5 days later with SHIVBG505. In comparison with all 12 control animals that became infected, all four animals infused with VRC34.01 (10 mg/kg) and three out of four animals infused with VRC34.01 (2.5 mg/kg) remained uninfected. Because of the lower potency of DF1W-a.01 and DFPH-a.15 against SHIVBG505, we infused both Abs at a higher dose of 100 mg/kg into four rhesus macaques each, followed by SHIVBG505 challenge 5 days later. Three of four animals that received DF1W-a.01 were protected against infection, whereas all animals that received DFPH-a.15 were protected. Overall, the protective serum neutralization titers observed in these animals were similar to what has been observed for other bNAbs in similar SHIV infection models and in human clinical trials. In conclusion, FP-directed mAbs can thus provide dose-dependent in vivo protection against mucosal SHIV challenges, supporting the development of prophylactic vaccines targeting the HIV-1 Env FP.