Rise In Titer Research Articles

The added value of serologic testing: A comparison of influenza incidence among pregnant persons based on molecular-based surveillance versus serologic testing

BackgroundWe examined the added value of serologic testing for estimating influenza virus infection incidence based on illness surveillance with molecular testing versus periodic serologic testing. MethodsPregnant persons unvaccinated against influenza at <28 weeks gestation were enrolled before the 2017 and 2018 influenza seasons in Peru and Thailand. Blood specimens were collected at enrollment and ≤14 days postpartum for testing by hemagglutination inhibition assay for antibodies against influenza reference viruses. Seroconversion was defined as a ≥4-fold rise in antibody titers from enrollment to postpartum with the second specimen's titer of ≥40. Throughout pregnancy, participants responded to twice weekly surveillance contacts asking about influenza vaccination and influenza-like symptoms (ILS). A mid-turbinate swab was collected with each ILS episode for influenza real-time reverse transcription polymerase chain reaction (rRT-PCR). ResultsOf 1,466 participants without evidence of influenza vaccination during pregnancy, 296 (20.2%) had evidence of influenza virus infections. Fifteen (5.1%) were detected by rRT-PCR only, 250 (84.4%) by serologic testing only, and 31 (10.5%) by both methods. ConclusionsInfluenza virus infections during pregnancy occurred in 20% of cohort participants; >80% were not detected by a broad illness case definition coupled with rRT-PCR.

Features of oxygen-independent metabolism of neutrophils in the animals sensitized with non-agglutinogenic Brucella strain

The results of evaluation of the peculiarities of functioning of non-enzymatic systems of neutrophils of peripheral blood of guinea pigs before immunization and on the 7th, 14th, 21st, 28th, 42nd, 55th, 69th, 125th days after immunization with Brucella R-strain are presented. Two groups of agouti guinea pigs were formed for the study: control and experimental. The experimental animals were immunized with a suspension of Brucella abortus strain 16/4 at a dose of 1 billion CFU/ml subcutaneously; the control pigs were intact to brucellosis. The activity of antimicrobial systems was evaluated by determining the indices of cationic proteins by photometric method in spontaneous and induced variants. Experimental samples of brucellosis antigens were used as specific inducers in the reaction procedure. It was found that the use of Brucella disintegrans at a concentration of 50 μg/ml and corpuscular antigens at a concentration of 100 μg/ml by protein in the test with cationic proteins as inducers of disintegrants has a stimulating effect on the intensity of cationic protein production in the cell suspension of leukocytes. Stimulation indices were calculated at all observation periods as the ratio of the index of the stimulated sample to the index of the sample without antigen load. Two peaks of stimulating activity of cationic proteins were observed in the course of the study: the maximum rise of stimulation indices was observed on the 14th day after immunization and a less pronounced rise on the 28th day. The peak of agglutinating antibody production was on the 21st day after immunization, complement-binding antibodies – on the 21st-28th day, less intensive rise in titers of agglutinating and complement-binding antibodies was noted on the 69th day. In these terms, a decrease in the stimulated activity of neutrophil cationic proteins was observed. The peak activity of non-enzymatic cationic proteins of neutrophils was found to be ahead of the peak of humoral immune response.

SEROLOGICAL RESPONSE TO CANINE DISTEMPER VACCINATION IN WILD CAUGHT RACCOONS (PROCYON LOTOR).

Canine distemper virus (CDV) is a well-known RNA virus that affects domestic dogs and all families of wild terrestrial carnivores. Spillover infections from wildlife to domestic animals are mitigated by preventive vaccination, but there is limited information on the off-label use of veterinary vaccines for wildlife like raccoons (Procyon lotor). Twenty wild-caught raccoons were inoculated with a commercial recombinant DNA canarypox-vectored CDV vaccine, applying a regimen of two serial doses by SC route with an interval of 25-28 days between doses. The CDV serum virus neutralizing antibody (VNA) baseline titers and the postvaccination titers were measured at fixed time points. Forty percent (8/20) of the wild-caught raccoons had CDV VNA titers of 1:8 or greater upon intake, and all but a single individual were juvenile animals. Approximately one month following the first vaccine dose, 8% (1/12) of raccoons seronegative at baseline had serum CDV VNA titers of 1:24 or greater. Approximately one month following the booster vaccine dose, 67% (8/12) of raccoons seronegative at baseline had serum CDV VNA titers of 1:24 or greater. Among raccoons with CDV VNA titers greater than or equal to 1:8 at baseline, 13% (1/8) demonstrated a fourfold or greater rise in titer one month after the first vaccine dose, whereas 38% (3/8) reached the same threshold one month after the booster dose. The presence of naturally acquired CDV VNA in juvenile raccoons at the time of vaccination may have interfered with the humoral VNA response. A regimen of at least two serially administered SC vaccine doses may be immunogenic for raccoons, but further investigation of alternative routes, regimens, and CDV vaccine products is also warranted for this species.

Sex Differences in Exercise-Induced Modulation of the Humoral Immune Response to Influenza Vaccination

Physical activity is known to modulate immune cell function and understanding its role in vaccine-induced immunity is critical for both optimizing vaccine strategies and implementing lifestyle factors that contribute to better immune health. This study aimed to elucidate the impact of physical activity on antibody responses following influenza vaccination, with a specific focus on biological sex differences among male and female cross-country athletes. Based on previous studies, we hypothesized that physical activity would increase immune responses, regardless of biological sex. Two cohorts of male and female Division III college cross-country runners and two cohorts of non-athletes (no physical activity) participated in this longitudinal investigation. Studies were conducted in two separate influenza seasons where participants received a quadrivalent seasonal influenza vaccine (2020-21 and 2022-23). An estimated non-adjusted VO2 max was calculated, and a survey was administered to identify overall health status prior to the start of the study. Blood samples were collected at predefined intervals to assess pre- and post-vaccination antibody responses specific for the H1N1 component of each seasonal influenza vaccine. VO2 max, a measure of overall fitness, was higher in the athletes as compared to those participants who were not physically active, and these results were consistent among both males and females. All participants mounted an immune response to the seasonal influenza vaccine as indicated by a rise in vaccine-specific antibody titers from pre-vaccination to post-vaccination. However, the differences in titers were sex specific, with greater neutralizing antibody titers in females as compared to males — regardless of their level of physical activity. When data were further partitioned by physical activity level, it was identified that although males have lower antibody responses than females, males that were cross country runners had significantly greater antibody responses than males that were not physically active. This study contributes valuable insights into the complex interplay between exercise, sex, and immune responses. Understanding these dynamics could inform recommendations for individuals to be engaged in regular physical activity to optimize overall immune health. This research was funded by a College of Saint Benedict and Saint John's University Faculty Development and Research Committee Award. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Dynamics of SARS-CoV-2 antibodies after natural infection: insights from a study on Pasteur Institute of Tunis employees

ABSTRACT This study aimed to assess the kinetics of antibodies against the SARS-CoV-2, following natural infection in a cohort of employees of the Institut Pasteur de Tunis (IPT) and to assess the risk of reinfection over a 12-months follow-up period. A prospective study was conducted among an open cohort of IPT employees with confirmed SARS-CoV-2 infection that were recruited between September 2020 and March 2021. Sera samples were taken at 1, 3, 6, 9 and 12 months after confirmation of COVID-19 infection and tested for SARS-CoV-2-specific immunoglobulin G (IgG) antibodies to the spike (S-RBD) protein (IgG anti-S-RBD) and for neutralizing antibodies. Participants who had an initial decline of IgG anti-S-RBD and neutralizing antibodies followed by a subsequent rise in antibody titers as well as those who tested positive for SARS-CoV-2 by RT-PCR after at least 60 days of follow up were considered as reinfected. In total, 137 individuals were included with a mean age of 44.7 ± 12.3 years and a sex-ratio (Male/Female) of 0.33. Nearly all participants (92.7%) were symptomatic, and 2.2% required hospitalization. Among the 70 participants with three or more prospective blood samples, 32.8% were reinfected among whom 11 (47.8%) reported COVID-19 like symptoms. Up to 12 months of follow up, 100% and 42.9% of participants had detectable IgG anti-S-RBD and neutralizing antibodies, respectively. This study showed that humoral immune response following COVID-19 infection may persist up to 12 months after infection despite the potential risk for reinfection that is mainly explained by the emergence of new variants.

A study of the immunomodulatory effects of coconut oil extract in broilers experimentally infected with velogenic Newcastle disease virus.

This study aims to evaluate the immunomodulatory effects of coconut oil extract (COE) in broilers experimentally infected with velogenic Newcastle disease virus (vNDV). A total of 150 broiler birds (day-old) were equally divided into five study groups i.e., negative control, positive control, COE-1, COE-2, and COE-3. On day 10, broilers of groups COE-1, COE-2, and COE-3 were supplemented with 1, 2, and 3 mL of COE respectively per liter of drinking water for 15 days. On day 13, 0.1 mL/bird (10-5.25 ELD50) of vNDV was inoculated in broilers of positive control, COE-1, COE-2, and COE-3 groups intramuscularly. During this study, growth performance, morbidity, and mortality rates of each study group were recorded. The antibody titer against NDV was determined on days 7, 14, 21, 28, and 35. The levels of immunoglobulins (IgY and IgM) were also determined on the 7th, 14th, and 21st days post-sheep red blood cells (SRBCs) inoculation. On day 33, avian tuberculin was injected between the 1st and 2nd toes of the left side (intradermally) to measure lymphoproliferative responses. On day 35, the phagocytic activity in the blood was assessed through a carbon clearance assay by injecting carbon black ink into the right-wing vein. The visceral organs having gross lesions were also collected for histopathology. The COE significantly improved the growth performance, and lowered the morbidity and mortality rates of broilers. There was a significant rise in antibody titers against NDV and levels of IgY and IgM antibodies against SRBC in COE-supplemented broilers. The lymphoproliferative response and phagocytic activity were also enhanced. Among COEsupplemented groups, the broilers of the COE-3 group showed a significant increase in growth performance and boosted immune defense. Coconut oil extract has the potential to boost the growth performance and immune status of broilers. It can be used effectively as a feed additive and alternative to antibiotics to prevent the spread of infectious poultry pathogens.

A phase 3 randomized, open-label study evaluating the immunogenicity and safety of concomitant and staggered administration of a live, pentavalent rotavirus vaccine and an inactivated poliomyelitis vaccine in healthy infants in China

ABSTRACT This open-label, randomized, phase 3 study in China (V260-074; NCT04481191) evaluated the immunogenicity and safety of concomitant and staggered administration of three doses of an oral, live, pentavalent rotavirus vaccine (RV5) and three doses of an intramuscular, inactivated poliomyelitis vaccine (IPV) in 400 healthy infants. The primary objective was the non-inferiority of neutralizing antibody (nAb) responses in the concomitant- versus the staggered-use groups. Antibody responses were measured at baseline and 1-month post-dose 3 (PD3). Parents/legal guardians recorded adverse events for 30 or 15 d after study vaccinations in the concomitant-use or staggered-use groups, respectively. At PD3, >98% of participants seroconverted to all three poliovirus types, and the primary objective was met as lower bounds of the two-sided 95% CI for between-group difference in nAb seroconversion percentages ranged from − 4.3% to − 1.6%, for all poliovirus types, p < .001. At PD3, geometric mean titers (GMTs) of nAb responses to poliovirus types 1, 2, and 3 in the concomitant-use group and the staggered-use group were comparable; 100% of participants had nAb titers ≥1:8 and ≥1:64 for all poliovirus types. Anti-rotavirus serotype-specific IgA GMTs and participants with ≥3-fold rise in postvaccination titers from baseline were comparable between groups. Administration of RV5 and IPV was well tolerated with comparable safety profiles in both groups. The immunogenicity of IPV in the concomitant-use group was non-inferior to the staggered-use group and RV5 was immunogenic in both groups. No safety concerns were identified. These data support the concomitant use of RV5 and IPV in healthy Chinese infants.

Prevalence and risk factors for Q fever, spotted fever group rickettsioses, and typhus group rickettsioses in a pastoralist community of northern Tanzania, 2016-2017.

In northern Tanzania, Q fever, spotted fever group (SFG) rickettsioses, and typhus group (TG) rickettsioses are common causes of febrile illness. We sought to describe the prevalence and risk factors for these zoonoses in a pastoralist community. Febrile patients ≥2 years old presenting to Endulen Hospital in the Ngorongoro Conservation Area were enrolled from August 2016 through October 2017. Acute and convalescent blood samples were collected, and a questionnaire was administered. Sera were tested by immunofluorescent antibody (IFA) IgG assays using Coxiella burnetii (Phase II), Rickettsia africae, and Rickettsia typhi antigens. Serologic evidence of exposure was defined by an IFA titre ≥1:64; probable cases by an acute IFA titre ≥1:128; and confirmed cases by a ≥4-fold rise in titre between samples. Risk factors for exposure and acute case status were evaluated. Of 228 participants, 99 (43.4%) were male and the median (interquartile range) age was 27 (16-41) years. Among these, 117 (51.3%) had C. burnetii exposure, 74 (32.5%) had probable Q fever, 176 (77.2%) had SFG Rickettsia exposure, 134 (58.8%) had probable SFG rickettsioses, 11 (4.8%) had TG Rickettsia exposure, and 4 (1.8%) had probable TG rickettsioses. Of 146 participants with paired sera, 1 (0.5%) had confirmed Q fever, 8 (5.5%) had confirmed SFG rickettsioses, and none had confirmed TG rickettsioses. Livestock slaughter was associated with acute Q fever (adjusted odds ratio [OR] 2.54, 95% confidence interval [CI] 1.38-4.76) and sheep slaughter with SFG rickettsioses case (OR 4.63, 95% CI 1.08-23.50). Acute Q fever and SFG rickettsioses were detected in participants with febrile illness. Exposures to C. burnetii and to SFG Rickettsia were highly prevalent, and interactions with livestock were associated with increased odds of illness with both pathogens. Further characterisation of the burden and risks for these diseases is warranted.

Tissue expression of porcine transient receptor potential mucolipin protein channels and their differential responses to porcine reproductive and respiratory syndrome virus infection in vitro

Abstract Introduction Porcine reproductive and respiratory syndrome virus (PRRSV) infection results in a serious disease, posing a huge economic threat to the global swine industry. The transient receptor potential mucolipin proteins (TRPMLs) have been shown to be strongly associated with virus infection and other physiological processes in humans, but their tissue distribution and responses to PRRSV in pigs remain unknown. Material and Methods Quantitative reverse-transcription PCR analysis was undertaken to determine the optimal primer for TRPML expression detection and for quantifying that expression individually in different pig tissue samples. Meat Animal Research Center 145 (MARC-145) monkey kidney cells and the TRPML-specific activator mucolipin synthetic agonist 1 (ML-SA1) were used to reveal the relationship between TRPML and PRRSV-2 infection. Results The best primers for each TRPML gene used in a fluorescence-based quantitative method were identified and TRPML1 was found to be highly expressed in the kidneys and liver of pigs, while TRPML2 and TRPML3 were observed to be primarily expressed in the kidney and spleen tissues. The expression of TRPML2 was upregulated with the rise in PRRSV-2 infection titre but not the expression of TRPML1 or TRPML3, and ML-SA1 inhibited PRRSV-2 in a dose-dependent manner. Conclusion Our research revealed the gene expression of TRPMLs in pigs and identified that TRPML channels may act as key host factors against PRRSV infection, which could lead to new targets for the prevention and treatment of pig infectious diseases.

Potential Protectivity of a Conjugated COVID-19 Vaccine against Tetanus.

PastoCovac is a subunit protein vaccine against COVID-19 which contains the tetanus toxoid as a carrier conjugated to SARS-CoV-2 RBD. The primary goal of the tetanus application was to elicit a stronger specific response in the individuals. However, conjugate vaccines have the potency to generate anticarrier antibodies in addition to the target antigen. Therefore, the present study aimed to evaluate the PastoCovac vaccine in the humoral immune induction against tetanus. Six groups of individuals, including those who received one, two, or three doses of the PastoCovac vaccine, Td vaccine, and also the controls who received other COVID-19 vaccines (except PastoCovac), were investigated. The anti-tetanus IgG was assessed by an ELISA assay in all vaccinated groups. The antibody persistency against tetanus in the group who received one dose of the PastoCovac vaccine was also assessed on day 60, 90, and 180 after the last injection. The anti-tetanus antibody titer in the three groups of PastoCovac recipients was positive, though additional doses of the vaccine led to a significant antibody rise (p = 0.003). Notably, the comparison of the mean antibody titer between the Td recipients and those who received one/two doses of PastoCovac showed that the mean rise in the antibody titer before and after the injection was not significant. Although the antibody titer on day 180 decreased to a lower level than on day 21, it was still estimated to be highly positive against tetanus. Eventually, none of the PastoCovac recipients presented vaccine side-effects during the follow-up. The current data indicate that the tetanus conjugate vaccine against COVID-19, PastoCovac, could induce immune responses against tetanus, which can persist for at least 6 months. Combination vaccine formulae containing TT and DT as carriers for conjugate vaccines could be considered instead of TT and/or DT boosters in adults if they are indicated.

Immune responses to typhoid conjugate vaccine in a two dose schedule among Nepalese children

BackgroundPreviously, the Vi-typhoid conjugate vaccine (Vi-TT) was found to be highly efficacious in Nepalese children under 16 years of age. We assessed the immunogenicity of Vi-TT at 9 and 12 months of age and response to a booster dose at 15 months of age. MethodsInfants were recruited at Patan Hospital, Kathmandu and received an initial dose of Vi-TT at 9 or 12 months of age with a booster dose at 15 months of age. Blood was taken at four timepoints, and antibody titres were measured using a commercial ELISA kit. The primary study outcome was seroconversion (4-fold rise in antibody titre) of IgG one month after both the doses. FindingsFifty children were recruited to each study group.Some visits were disrupted by the COVID19 pandemic and occurred out of protocol windows.Both the study groups attained 100 % IgG seroconversion after the initial dose. IgG seroconversion in the 9-month group was significantly higher than in the 12-month group (68.42 % vs 25.8 %, p < 0.001). Among individuals who attended visits per protocol, IgG seroconversion after the first dose occurred in 100 % of individuals (n = 27/27 in 9-month and n = 32/32 in 12-month group). However, seroconversion rates after the second dose were 80 % in the 9-month and 0 % in the shorter dose-interval 12-month group (p < 0.001) (n = 16/20 and n = 0/8, respectively). InterpretationVi-TT is highly immunogenic at both 9 and 12 months of age. Stronger response to a booster in the 9-month group is likely due to the longer interval between doses.

Haemato-Immunological Response of Immunized Atlantic Salmon (Salmo salar) to Moritella viscosa Challenge and Antigens.

Winter ulcer disease is a health issue in the Atlantic salmonid aquaculture industry, mainly caused by Moritella viscosa. Although vaccination is one of the effective ways to prevent bacterial outbreaks in the salmon farming industry, ulcer disease related to bacterial infections is being reported on Canada's Atlantic coast. Here, we studied the immune response of farmed immunized Atlantic salmon to bath and intraperitoneal (ip) M. viscosa challenges and evaluated the immunogenicity of M. viscosa cell components. IgM titers were determined after infection, post boost immunization, and post challenge with M. viscosa. IgM+ (B cell) in the spleen and blood cell populations were also identified and quantified by 3,3 dihexyloxacarbocyanine (DiOC6) and IgM-Texas red using confocal microscopy and flow cytometry. At 14 days post challenge, IgM was detected in the serum and spleen. There was a significant increase in circulating neutrophils 3 days after ip and bath challenges in the M. viscosa outer membrane vesicles (OMVs) boosted group compared to non-boosted. Lymphocytes increased in the blood at 7 and 14 days after the ip and bath challenges, respectively, in OMVs boosted group. Furthermore, a rise in IgM titers was detected in the OMVs boosted group. We determined that a commercial vaccine is effective against M. viscosa strain, and OMVs are the most immunogenic component of M. viscosa cells.

Longitudinal phase 2 clinical trials of live, attenuated tularemia vaccine in healthy research laboratory workers

BackgroundTularemia is caused by the intracellular bacterium Francisella tularensis (Ft). It was weaponized historically due to low infectious aerosol dose, high morbidity, and mortality rates for pneumonic disease. The US Army developed the attenuated Live Vaccine Strain (LVS) from stocks provided by the former Soviet Union in the 1950s. The vaccine has been safe and immunogenic over the ensuing decades in multiple clinical trials including human challenge studies.MethodsTwo sequential FDA-regulated, non-randomized, single-arm LVS trials enrolled at-risk laboratory personnel working on tularemia in bio-containment laboratories under IND#157. Volunteers received a single dose of LVS manufactured in 1962 by scarification. Positive immunization was based on local scarification site “take reaction,” and either a &amp;gt;1:20 tularemia antigen microagglutination (MA) titer (protocol FY03-24; 2004-8) or &amp;gt;4-fold rise in MA titer (protocol FY07-15; 2009-2017). Those still negative by week 4 were offered a second dose.ResultsThe LVS vaccine was safe, well tolerated, and highly immunogenic. Between the two studies, all recipients (100%) had positive “take reactions,” with 95.5% of those in study FY03-24 having a positive response following initial vaccination. All but three subjects (98%) in protocol FY03-24 had positive MA titer results defined as &amp;gt;1:20, most within 28–35 days. In protocol FY07-15, 95% of subjects had a 4-fold or greater rise in MA titer, the primary immunogenicity endpoint for that study.DiscussionLVS vaccine administered to laboratory workers at risk for tularemia exposure over 12 years was safe and highly immunogenic. Response rates remained robust despite the vaccine lots employed having been manufactured 42–55 years prior to vaccination. The results and historical comparator data presented here serve as a benchmark for future studies. LVS remains unlicensed due to instability in culture and the potential for reversion to the wild-type pathogen. Despite the threat, there are no FDA-approved vaccines. In the absence of a clinical-stage commercial development effort, an ongoing LVS vaccine protocol under investigational new drug (IND) application for at-risk laboratory workers to prevent occupationally acquired disease should be considered based on extensive favorable data for this vaccine.Clinical trial registrationClinicalTrials.gov, identifiers NCT00584844 (trial FY03-24) and NCT00787826 (trial FY07-15).

Immunological Effect of the drug “Immune”- an Ayurveda medication in COVID-19 patients- A Randomized Control Trial

Introduction: The Pandemic of SARS COV-2 continues to be a global health threat which has affected 140 million cases all over the world with 3.01million deaths with the main underlying main cause of raised inflammatory markers. India is well known for the birth of Ayurveda – the potential therapeutic agents have been developed having combination of already proven drugs for research. Objectives: To measure the effect of drug- “Immune” on the neutralizing antibody levels along with inflammatory markers among mild to moderate symptomatic COVID-19 subjects. Material and methods: Triple blinded Randomized Controlled Trial was adopted in our study among mild and moderate cases of COVID-19. Two groups- each having 25 subjects were intervened along with standard care of treatment where one was getting the drug immune consisting of Withania somnifera , glycrrhizine gabra , Cederus Deodara and Leptadenia Reticulata in Arka preparation and other were getting placebo which was blinded by labelling as drug A and Drug B. These two groups were followed up for antibody testing and inflammatory markers such as interleukin-6,D-dimer,serum ferritin and lactate dehydrogenase were also assessed. Results: There was a statistical significant rise in antibody titres(P value&lt;0.05) with drug A compared to drug B which was later revealed to be drug immune and we could also found reduction in inflammatory marker mainly lactate dehydrogenase. Conclusion: This drug “Immune” proved to be of clinical significance with raised antibody titre and reduction of some of the inflammatory markers. And this can play a pivotal therapeutic agent to reduce the morbidity and mortality associated with SARS COV-2

Incidence of ANA Positivity After the Administration of Biologicals

Background: Antinuclear antibodies (ANA) are often used in diagnosing autoimmune rheumatological diseases, but their behavior in response to biological therapies, particularly in Asian patients, is not well-documented. The impact of these therapies on ANA status is crucial for understanding disease management and treatment efficacy. This study aims to evaluate the prevalence and significance of ANA positivity following the administration of biological agents in patients with autoimmune rheumatological diseases. Methods: This pilot study was a prospective cohort study involving 100 patients with autoimmune rheumatological diseases who were initially ANA negative at baseline. Predominantly included patients were axial spondyloarthritis (AxSpA) (n=95) and ANCA vasculitis (n=5). Patients with AxSpA were diagnosed according to the 2009 ASAS criteria, and treated with biological agents (e.g., TNF inhibitors such as adalimumab, etanercept, or IL-17 inhibitors such as secukinumab) and followed at a tertiary care center in India from January 2021 to December 2023. ANA levels were measured before and after 3, 6, 9, or 12 months of biological therapy. Changes in ANA positivity, clinical outcomes, and correlations with disease activity were analyzed. Results: Out of the 100 patients enrolled, 67 (67%) completed the study. All participants were ANA negative at baseline. After biological therapy, ANA positivity developed in 4 patients (5.9%). Despite this increase in Ana positivity, there was no significant correlation between ANA positivity and clinical disease activity, as measured by the Ankylosing Spondylitis Disease Activity Score (ASDAS) and the visual analog scale (VAS) for pain, BVAS suggesting effective therapeutic response despite changes in ANA status. Additionally, 30 patients were lost to follow-up, highlighting challenges related to the financial sustainability of biological therapy in the resource limited countries. Conclusion: Biological therapies for AxSpA are associated with an increase in ANA positivity although this change does not appear to impact clinical disease activity. The rise in ANA titres may reflect disease-related changes or treatment effects rather than a direct correlation with therapeutic efficacy. Further longitudinal studies are needed to understand the clinical significance of these findings and to refine the interpretation of ANA results during biological therapy.

Selenium nanoparticles effect on foot and mouth disease vaccine in local Awassi breed male lambs.

The goal of this research was to evaluate where selenium nanoparticles impact the activity of antibodies in immunized lambs with foot and mouth vaccines by modulating the immune system. Two groups of lambs of 3-4 months of age were injected with 1 ml of ARRIAH-VAC vaccine intramuscularly in the neck, five Lambs were given selenium nanoparticles (size 100 nm) oral administration of selenium nano dose of 0.1 mg/kg of body mass once every day for sixty days considered as group one (G1) while the other five used as control Group 2 (G2). This resulted in the establishment of an immune response, as evidenced by a rise in antibody titer in the blood using the ELISA test for three serotypes A, O, and Asia 1, when selenium nanoparticles were given orally at a dose of 0.1 mg/kg body weight after immunization, we noticed a significant (p >0:05) selenium nano group increase in IgG response in all immunized groups in contrast to lambs that had only received the foot-and-mouth disease vaccine. We have demonstrated that selenium nanoparticles administered orally significantly enhance immune responses while also increasing body weight.

Immunogenicity of the Conjugate Meningococcal ACWY-TT Vaccine in Children and Adolescents Living with HIV.

Children and adolescents living with HIV (CALHIV) are at high risk of meningococcal infections and may present lower immune responses to vaccines. The objectives of this study were to assess the immunogenicity of the quadrivalent Men ACWY-TT vaccine (Nimenrix®) in CALHIV after a two-dose schedule and to describe possible HIV-related factors that may affect the immunogenic response. A multicenter prospective study was designed, including CALHIV followed in five hospitals in Madrid, between 2019 and 2021. Two doses of the Men ACWY-TT vaccine were administered. Serum bactericidal antibody (SBA) assays using rabbit complement (rSBA) against serogroups C, W, and Y were used to determine seroprotection and vaccine response (the proportion achieving a putative protective titer of ≥eight or a ≥four-fold rise in titer from baseline). Serum was collected at baseline, and at 3 and 12 months after vaccination. There were 29 CALHIV included, 76% of whom were perinatally infected. All were receiving TAR and presented a good immunovirological and clinical status overall. At baseline, 45% of CALHIV had seroprotective titers to at least one serogroup, with individual seroprotection rates of 24%, 28%, and 32% against C, W, and Y, respectively. After a two-dose schedule, vaccine response was 83% for each serogroup, eliciting a vaccine response to all serogroups in 69% of them. One year after vaccination, 75% of CALHIV maintained seroprotective titers against the C serogroup, and 96% against W and Y. None of the HIV-related characteristics analyzed could predict vaccine response or antibody duration. CALHIV who received effective TAR and presented a good immuno-virological situation achieved an appropriate vaccine response after two doses of the Men ACWY-TT vaccine, and antibody-mediated protection against serogroups C, W, and Y was maintained in more than 70% of the patients one year after vaccination.

Prevalence and risk factors for human leptospirosis at a hospital serving a pastoralist community, Endulen, Tanzania.

Leptospirosis is suspected to be a major cause of illness in rural Tanzania associated with close contact with livestock. We sought to determine leptospirosis prevalence, identify infecting Leptospira serogroups, and investigate risk factors for leptospirosis in a rural area of Tanzania where pastoralist animal husbandry practices and sustained livestock contact are common. We enrolled participants at Endulen Hospital, Tanzania. Patients with a history of fever within 72 hours, or a tympanic temperature of ≥38.0°C were eligible. Serum samples were collected at presentation and 4-6 weeks later. Sera were tested using microscopic agglutination testing with 20 Leptospira serovars from 17 serogroups. Acute leptospirosis cases were defined by a ≥four-fold rise in antibody titre between acute and convalescent serum samples or a reciprocal titre ≥400 in either sample. Leptospira seropositivity was defined by a single reciprocal antibody titre ≥100 in either sample. We defined the predominant reactive serogroup as that with the highest titre. We explored risk factors for acute leptospirosis and Leptospira seropositivity using logistic regression modelling. Of 229 participants, 99 (43.2%) were male and the median (range) age was 27 (0, 78) years. Participation in at least one animal husbandry practice was reported by 160 (69.9%). We identified 18 (7.9%) cases of acute leptospirosis, with Djasiman 8 (44.4%) and Australis 7 (38.9%) the most common predominant reactive serogroups. Overall, 69 (30.1%) participants were Leptospira seropositive and the most common predominant reactive serogroups were Icterohaemorrhagiae (n = 20, 29.0%), Djasiman (n = 19, 27.5%), and Australis (n = 17, 24.6%). Milking cattle (OR 6.27, 95% CI 2.24-7.52) was a risk factor for acute leptospirosis, and milking goats (OR 2.35, 95% CI 1.07-5.16) was a risk factor for Leptospira seropositivity. We identified leptospirosis in approximately one in twelve patients attending hospital with fever from this rural community. Interventions that reduce risks associated with milking livestock may reduce human infections.

Impact of age at vaccination and cervical HPV infection status on binding and neutralizing antibody titers at 10 years after receiving single or higher doses of quadrivalent HPV vaccine

ABSTRACT Long-term follow-up of a cohort of unmarried girls who received one, two, or three doses of quadrivalent HPV vaccine, between 10 and 18 years of age, in an Indian multi-centric study allowed us to compare antibody responses between the younger and older age cohorts at 10-years post-vaccination, and study the impact of initiation of sexual activity and cervical HPV infections on antibody levels. Among the younger (10–14 years) recipients of a single dose, 97.7% and 98.2% had detectable binding antibody titers against HPV 16 and HPV 18 respectively at ten years post-vaccination. The proportions among those receiving a single dose at age 15–18 years were 92.3% and 94.2% against HPV 16 and HPV 18 respectively. Mean HPV 16 binding antibody titers were 2.1 folds (95%CI 1.4 to 3.3) higher in those vaccinated at ages 10–14 years, and 1.9 folds (95%CI 1.2 to 3.0) higher in those vaccinated at 15–18 years compared to mean titers seen in the unvaccinated women. Compared to previous timepoints of 36 or 48 months, binding antibodies against HPV 16 and neutralizing antibodies against both HPV 16 and HPV 18 were significantly higher at 10 years. This rise was more pronounced in participants vaccinated at 15–18 years. No association of marital status or cervical HPV infections was observed with the rise in titer. Durability of antibody response in single dose recipients correlated well with the high efficacy of a single dose against persistent HPV 16/18 infections irrespective of age at vaccination, as we reported earlier.

1719. Duration of antibodies after immunization with the quadrivalent influenza vaccine in children after hematopoietic stem cell transplantation or chemotherapy compared to healthy children

Abstract Background Children that have undergone hematopoietic stem cell transplantation (HSCT) are at a higher risk for severe influenza. The purpose of this study was to compare the duration of antibodies after immunization with the quadrivalent influenza vaccine (QIV) in children after hematopoietic stem cell transplantation or chemotherapy compared to healthy children. Methods This was a prospective study of children below 18 years old that received the QIV influenza vaccine during the 2021-2022 influenza vaccination season. Children were divided into 3 groups as follows: a) post-HSCT, b) post-chemotherapy, and c) immunocompetent children as a healthy control. Blood samples were taken immediately before immunization, at 1 month, 3 months, 6 months, and 12 months after immunization. Hemagglutination Inhibition (HI) assays were performed. Seropositive rate was defined by the percentage of patients with HI titer ≥1:40. Seroconversion rate (SCR) was defined as follows: 1) in patients with a pre-vaccination HI titer &amp;lt; 1:10, rise in post-vaccination HI titers ≥1:40, or in patients with pre-vaccination HI titers ≥1:40, a 4-fold increase. Results A total of 60 children were included in the preliminary analyses, n=20 in each of the three groups. The SPR at post-vaccination 1 month for both A/H1N1 and H3N2 exceeded 80% in all three groups. The SPR remained above 60% at 3 months post-immunization for both A antigens. However, by 6 months post-vaccination, the SPR dropped to 50% in the post-chemotherapy group for the A/H1N1 antigen, and the geometric mean titers (GMTs) were 26.39. For B/Victoria and B/Yamagata, the SPR was below 40% in the post-HSCT and post chemotherapy group at 1 months and below 20% by 3 months. The GMTs were also below 1:40 for both antigens. In the normal control group, the SPR for B/Victoria was 50% at 1 months and 45% at 3 months post-immunization, and for B/Yamagata, 50% at 1 months and 55% at 3 months post-immunization. However, the GMTs were below 1:40 by 3 months post-immunization. Conclusion For A/H1N1, the SPR and GMTs at 6 months in the post-chemotherapy was low. In both the post-HSCT and chemotherapy group, HI titers were low for both B antigens at 1-month post-vaccination, and GMTs showed &amp;lt; 1:40. B antigens contained within QIV need to illicit better protection against Influenza in children. Disclosures All Authors: No reported disclosures