Passive Antibody Research Articles

A novel small molecule phagocytosis inhibitor, KB-208, ameliorates ITP in mouse models with similar efficacy as IVIG.

The characteristic feature of immune cytopenias involves the process of extravascular phagocytosis, wherein macrophages in the spleen and/or liver engage in the destruction of blood cells that have been opsonized by auto- or alloantibodies. Therefore, new treatments that prevent phagocytosis will be advantageous, especially for short-term usage along with alternative options. KB-208, a small molecule drug, previously shown to be efficacious for the in vitro inhibition of phagocytosis was synthesized. A passive antibody mouse model of immune thrombocytopenia (ITP) was used. Three different mouse strains (BALB/c, C57BL/6, CD1) were used to determine the efficacy of KB-208 compared with IVIG to ameliorate the ITP. Toxicity was investigated after 60-day chronic administration of KB-208 by a biochemistry panel, gross necroscopy and histopathology. KB-208 showed similar efficacy to ameliorate the thrombocytopenia compared with IVIG in all three mouse strains. This small molecule drug was effective at 1 mg/kg in ameliorating ITP, in comparison with IVIG at 1000-2500 mg/kg. KB-208 did not affect other blood parameters or elevate serum biochemistry markers of toxicity nor were any abnormal histopathological findings found. KB-208 is similar to IVIG for the amelioration of ITP in multiple mouse strains. Chronic administration of KB-208 for 60 days did not demonstrate in vivo toxicity. These findings indicate that KB-208 is efficacious, without significant in vivo toxicities in mice, and is a potential small molecule candidate for further evaluation to be used in the treatment of ITP and possibly all immune cytopenias where phagocytosis is responsible for the pathophysiology.

Passive Anti-amyloid Beta Monoclonal Antibodies: Lessons Learned over Past 20 Years.

Alzheimer's disease (AD) is a neurodegenerative disorder that significantly impairs cognitive and functional abilities, placing a substantial burden on both patients and caregivers. Current symptomatic treatments fail to halt the progression of AD, highlighting the urgent need for more effective disease-modifying therapies (DMTs). DMTs under development are classified as either passive or active on the basis of their mechanisms of eliciting an immune response. While this review will touch on active immunotherapies, we primarily focus on anti-amyloid beta monoclonal antibodies (mAbs), a form of passive immunotherapy, discussing their multifaceted role in AD treatment and the critical factors influencing their therapeutic efficacy. With two mAbs now approved and prescribed in the clinical setting, it is crucial to reflect on the lessons learned from trials of earlier mAbs that have shaped their development and contributed to their current success. These insights can then guide the creation of even more effective mAbs, ultimately enhancing therapeutic outcomes for patients with AD while minimizing adverse events.

Impact of immunoglobulin preparations on anti-HLA antibody specificity analysis

Abstract Background Donor-specific antibodies (DSAs) targeting human leukocyte antigens (HLAs) substantially reduce the longevity of transplanted organs. Desensitization of DSA-positive renal transplant recipients is achieved through intravenous administration of immunoglobulin (IVIg). However, the presence and detectability of anti-HLA antibodies in IVIg preparations following administration are not fully understood. We aimed to assess whether immunoglobulin preparations contain anti-HLA antibodies that can be detected as passive antibodies when administered into the body. Methods We evaluated 3 immunoglobulin preparations from different pharmaceutical companies, using anti-HLA class I and II antibody specificity tests and immunocomplex capture fluorescence analysis (ICFA). Results Direct testing for anti-HLA antibodies resulted in high background errors, particularly for Venoglobulin. Diluting Venoglobulin to physiological concentrations revealed the presence of anti-HLA class I antibodies; however, no common alleles were found between the specificity identification test and ICFA. For Glovenin and Venilon, anti-HLA class I and II antibodies were detected; however, variability was observed across different test reagent lots. Moreover, dilution of the globulin formulation revealed a prozone phenomenon. Conclusion The administration of IVIg complicates the accurate detection of anti-HLA antibodies, underscoring the need for careful interpretation of test results post-IVIg administration.

Assessing hepatitis B virus serologies when transitioning patients from intravenous immune globulin therapy to rituximab for the treatment of autoimmune neuromuscular diseases.

Intravenous immune globulin (IVIG) has been used as early treatment for autoimmune neuromuscular diseases, but due to cost and frequency, may be switched to rituximab. Rituximab and other B-cell-depleting medications require screening of hepatitis B virus (HBV) serologies given the risk of HBV reactivation (HBVr). We aimed to describe the incidence and characteristics of passively transferred antiviral serologies from IVIG and how to differentiate between passive antibody transfer and resolved HBV infection. This was a single-center descriptive study of neurology patients prescribed rituximab and IVIG. Retrospective medical record reviews were performed and patient-specific variables were collected. Twelve patients had reactive anti-HBc results after starting IVIG, but only 9 were confirmed to have reactive anti-HBc from passive transfer. Whether reactive anti-HBc in the remaining three patients was from passive IVIG transfer could not be confirmed. Five patients with reactive anti-HBc results during rituximab screening did not have pre-IVIG anti-HBc results for comparison and were started on antiviral prophylaxis. Reactive anti-HBc serologies changed to nonreactive after IVIG discontinuation 44-321 days after the last IVIG infusion. This study confirms IVIG can passively transfer anti-HBc serologies in a neurologic cohort. Ideally, HBV serologies would be checked before starting IVIG to help later determine if passive transfer occurred. With the increasing use of B-cell-depleting medications for neuromuscular conditions, it is important for providers to be knowledgeable on the interpretation of HBV serologies for patients on IVIG and to ensure implementation of an HBVr prophylaxis management strategy for patients when appropriate.

The role of convalescent plasma and hyperimmune immunoglobulins in the COVID-19 pandemic, including implications for future preparedness.

When Coronavirus Disease-19 (COVID-19) struck the world in December 2019, initiatives started to investigate the efficacy of convalescent plasma, a readily available source of passive antibodies, collected from recovered patients as a therapeutic option. This was based on historical observational data from previous virus outbreaks. A scoping review was conducted on the efficacy and safety of convalescent plasma and hyperimmune immunoglobulins for COVID-19 treatment. This review included the latest Cochrane systematic review update on 30-day mortality and safety. We also covered use in pediatric and immunocompromised patients, as well as the logistic challenges faced in donor recruitment and plasma collection in general. Challenges for low resource countries were specifically highlighted. A major challenge is the high donation frequency required from first-time donors to ensure a safe product, which minimizes the risk of transfusion-transmitted infectious. This is particularly difficult in low- and middle- income countries due to inadequate infrastructure and insufficient blood product supplies. High-certainty evidence indicates that convalescent plasma does not reduce mortality or significantly improve clinical outcomes in patients with moderate to severe COVID-19 infection. However, CCP may provide a viable treatment for patients unable to mount an endogenous immune response to SARS-CoV-2, based on mostly observational studies and subgroup data of published and ongoing randomized trials. Convalescent plasma has been shown to be safe in adults and children with COVID-19 infection. However, the efficacy in pediatric patients remains unclear. Data on efficacy and safety of CCP are still underway in ongoing (randomized) studies and by reporting the challenges, limitations and successes encountered to-date, research gaps were identified to be addressed for the future. This experience serves as a valuable example for future pandemic preparedness, particularly when therapeutic options are limited, and vaccines are either being developed or ineffective due to underlying immunosuppression.

Triple Combinations of AAV9-Vectors Encoding Anti-HIV bNAbs Provide Long-Term In Vivo Expression of Human IgG Effectively Neutralizing Pseudoviruses from HIV-1 Global Panel.

Anti-human immunodeficiency virus (HIV) broadly neutralizing antibodies (bNAbs) offer a promising approach for the treatment of HIV-1. The current paradigm for antibody therapy involves passive antibody transfer, requiring regular delivery of bNAbs in treating chronic diseases such as HIV-1. An alternative strategy is to use AAV-mediated gene transfer to enable in vivo production of desirable anti-HIV-1 antibodies. In this study, we investigated two sets of triple combinations of AAV9-vectors encoding different bNAbs: N6, 10E8, 10-1074 (CombiMab1), and VRC07-523, PGDM1400, 10-1074 (CombiMab2). We used CBAxC57Bl and C57BL/6 mouse models to characterize rAAV-induced antibody expression and to evaluate the neutralization capacity of mouse sera against a global panel of HIV-1 viral strains. rAAV9-mediated IgG expression varied between bNAb clones and mouse strains, with C57BL/6 mice exhibiting higher bNAb titers following rAAV delivery. Although CombiMab2 treatment elicited a higher IgG titer than CombiMab1, both combinations resulted in neutralization of all the viral strains from the global HIV-1 panel. Our data highlight the potential of AAV vectors as a long-term option for HIV-1 therapy.

Convalescent Plasma and Other Antibody Therapies for Infectious Diseases-Lessons Learned from COVID-19 and Future Prospects.

Antiviral passive antibody therapy includes convalescent plasma, hyperimmune globulin, and monoclonal antibodies. Passive antibodies have proven effective in reducing morbidity and mortality for SARS-CoV-2 and other infectious diseases when given early in the disease course with sufficiently high specific total and neutralizing antibody levels. Convalescent plasma can be delivered to patients before vaccination implementation or novel drug production. Carefully designed and executed randomized controlled trials near the pandemic outset are important for regulatory bodies, healthcare workers, guideline committees, the public, and the government. Unfortunately, many otherwise well-designed antibody-based clinical trials in COVID-19 were futile, either because they intervened too late in the disease or provided plasma with insufficient antibodies. The need for early treatment mandates outpatient clinical trials in parallel with inpatient trials. Early outpatient COVID-19 convalescent plasma transfusion with high antibody content within 9days of symptom onset has proven effective in blunting disease progression and reducing hospitalization, thus reducing hospital overcrowding in a pandemic. Convalescent plasma offers the opportunity for hope by enabling community participation in outpatient curative therapy while monoclonal therapies, vaccines, and drugs are being developed. Maintaining the appropriate infrastructure for antibody infusion in both outpatient and inpatient facilities is critical for future pandemic readiness.

Varicella-Zoster Virus Pretransplant Vaccination and Posttransplant Infections Among Pediatric Solid Organ Recipients in the Two-Dose Varicella Era: A Single-Center, Multi-Organ Retrospective Study.

Varicella-zoster virus (VZV) pretransplant immunization rates, exposures, and posttransplant disease are poorly characterized among pediatric solid organ transplant (SOT) recipients in the two-dose varicella vaccine era. A retrospective analysis of the electronic health records among children <18 years old who received SOT from January 1, 2011 through December 31, 2021, was performed at a single center to assess for missed pretransplant varicella vaccination opportunities, characterize VZV exposures, and describe posttransplant disease. Among 525 children, 444 were ≥6 months old (m.o.) at SOT with a documented VZV vaccine status. Eighty-five (19%) did not receive VZV Dose One; 30 out of 85 (35%) could have been immunized. Infants 6-11 m.o. accounted for 14 out of 30 (47%) missed opportunities. Among children ≥12 m.o. with documented Dose Two status (n = 383), 72 had missed vaccination opportunities; 57 out of 72 (79%) were children 1-4 years old. Most children had unclassifiable pre-SOT serostatus as varicella serology was either not obtained/documented (n = 171) or the possibility of passive antibodies was not excluded (n = 137). Of those with classified serology (n = 188), 69 were seroimmune. Forty-seven of 525 (9%) children had recorded VZV exposures; two developed varicella-neither had documented pre-SOT seroimmunity nor had received post-exposure prophylaxis. Nine additional children had medically attended disease: four primary varicella and five zoster. Of the 11 cases, 10 had cutaneous lesions without invasive disease; one had multi-dermatomal zoster with transaminitis. Seven (64%) received treatment exclusively outpatient. VZV exposure and disease still occur. Optimizing immunization among eligible candidates and ensuring patients have a defined VZV serostatus pretransplantation remain goals of care.

Passive infusion of an S2-Stem broadly neutralizing antibody protects against SARS-CoV-2 infection and lower airway inflammation in rhesus macaques.

The continued evolution of SARS-CoV-2 variants capable of subverting vaccine and infection-induced immunity suggests the advantage of a broadly protective vaccine against betacoronaviruses (β-CoVs). Recent studies have isolated monoclonal antibodies (mAbs) from SARS-CoV-2 recovered-vaccinated donors capable of neutralizing many variants of SARS-CoV-2 and other β-CoVs. Many of these mAbs target the conserved S2 stem region of the SARS-CoV-2 spike protein, rather the receptor binding domain contained within S1 primarily targeted by current SARS-CoV-2 vaccines. One of these S2-directed mAbs, CC40.8, has demonstrated protective efficacy in small animal models against SARS-CoV-2 challenge. As the next step in the pre-clinical testing of S2-directed antibodies as a strategy to protect from SARS-CoV-2 infection, we evaluated the in vivo efficacy of CC40.8 in a clinically relevant non-human primate model by conducting passive antibody transfer to rhesus macaques (RM) followed by SARS-CoV-2 challenge. CC40.8 mAb was intravenously infused at 10mg/kg, 1mg/kg, or 0.1 mg/kg into groups (n=6) of RM, alongside one group that received a control antibody (PGT121). Viral loads in the lower airway were significantly reduced in animals receiving higher doses of CC40.8. We observed a significant reduction in inflammatory cytokines and macrophages within the lower airway of animals infused with 10mg/kg and 1mg/kg doses of CC40.8. Viral genome sequencing demonstrated a lack of escape mutations in the CC40.8 epitope. Collectively, these data demonstrate the protective efficiency of broadly neutralizing S2-targeting antibodies against SARS-CoV-2 infection within the lower airway while providing critical preclinical work necessary for the development of pan-β-CoV vaccines.

Foals of mares vaccinated for Hendra virus have a suboptimal response to HeV vaccination

Hendra virus (HeV) is lethal to horses and a zoonotic threat to humans in Australia, causing severe neurological and/or respiratory disease with high mortality. An equine vaccine has been available since 2012. Foals acquire antibodies from their dams by ingesting colostrum after parturition, therefore it is assumed that foals of mares vaccinated against HeV will have passive HeV antibodies circulating during the first several months of life until they are actively vaccinated. However, no studies have yet examined passive or active immunity against HeV in foals. Here, we investigated anti-HeV antibody levels in vaccinated mares and their foals. Testing for HeV neutralising antibodies is cumbersome due to the requirement for Biosafety level 4 (BSL-4) containment to conduct virus neutralisation tests (VNT). For this study, a subset of samples was tested for HeV G-specific antibodies by both an authentic VNT with infectious HeV and a microsphere-based immunoassay (MIA), revealing a strong correlation. An indicative neutralising level was then applied to the results of a larger sample set tested using the MIA. Mares had high levels of HeV-specific neutralising antibodies at the time of parturition. Foals acquired high levels of maternal antibodies which then waned to below predictive protective levels in most foals by 6 months old when vaccination commenced. Foals showed a suboptimal response to vaccination, suggesting maternal antibodies may interfere with active vaccination. The correlation analysis between the authentic HeV VNT and HeV MIA will enable further high throughput serological studies to inform optimal vaccination protocols for both broodmares and foals.

Alpha-Synuclein Targeting Monoclonal Antibody Therapy Treatment for Parkinson’s Disease

An investigation was done on plausible antibody treatments for alpha-synuclein, which is an instigator for the dopamine-lacking neurodegenerative disease Parkinson’s to occur in patients due to its aggregation. Trials working towards slowing the pathogenesis of Parkinson’s Disease through monoclonal antibodies for alpha-synuclein were analyzed. Previously, similar therapies were done in other neurodegenerative diseases like Alzheimer’s, allowing for a hopeful hypothesis in Parkinson’s. Active and Passive antibody treatments were compared and discussed: Pranizeumab, Cipanemab, PD01A, and UB-312. Trials often found success in animal models and not the same outcome in humans within the passive studies. In active studies, however, more hopeful results were presented, showing built immunity towards alpha-synuclein and enhancement of motor symptoms. Though some studies led to a dead end, studies use information to complete future phases. Monoclonal antibody treatment for Parkinson’s Disease is a real future in the fight for reducing the pathogenesis of Parkinson’s Disease.

Immune response and protection of neonatal, colostrum-fed calves with modified live, intranasal, tri-valent vaccine using an experimental challenge with virulent bovine respiratory syncytial virus

Bovine respiratory syncytial virus (BRSV) is major viral con­tributor to bovine respiratory disease (BRD). BRD is a major cause of morbidity and mortality in all classes of cattle but par­ticularly young beef and dairy calves. Passive antibodies not only help protect the calf against infection, but may interfere with the immune responses following vaccination. The objective of this study was to evaluate the efficacy and immune response of an intranasal modified live virus (MLV) trivalent vaccine in the presence of well-defined maternal passive immunity.

Acetylcholine Binding Receptor Positivity from Passive Antibody Transfer in a Case of Progressive Muscular Atrophy (P11-11.009)

Acetylcholine Binding Receptor Positivity from Passive Antibody Transfer in a Case of Progressive Muscular Atrophy (P11-11.009)

Evaluation of the immune response of layer chickens to Newcastle disease virus vaccines using the new vaccination regimens.

The study aimed to evaluate the immunological response of layer chickens to live Newcastle disease virus vaccine using a newly developed vaccine schedule administered via the ocular route, as well as assess the persistence of passive antibodies in layer chickens and the effectiveness of protection against strains of the virus. A total of 140-day-old Lohmann Brown chicks were randomly divided into seven groups, 20 chicks each. Groups 1-3 received a single eye instillation of the vaccine at ages 5, 26 and 54 days, respectively, whereas groups 4-6 received a double eye instillation. Group 7 served as non-vaccinated control group. Ten days after immunization, samples were taken from hens that had received the vaccine at ages 15, 36 and 64, as well as from control chickens that had not received the vaccine at ages 5, 15, 21 and 31. A total of 10 serum samples from all chickens exhibited protective antibodies, and booster doses resulted in the highest haemagglutination inhibition titre. No significant change in antibody production was observed among layer hens (p>0.05). The study found that the La Sota (GMT±SD: 6.71±4.96), La Sota (GMT±SD: 8.00±0.00) and thermostable I2 (GMT±SD: 7.60±6.02), vaccination schedules provided the maximum immune response in single eye instillation, whereas the HB1 (GMT±SD: 7.11±4.77), La Sota (GMT±SD: 7.83±5.76) and La Sota (GMT±SD: 7.60±6.02), combination was the second-best vaccination schedule in double eye instillation. Furthermore, maternally-derived antibodies were maintained up to 31 days of age, indicating the level of passive immunity prior to vaccination. Characteristic lesions, such as edematous and diphtheria mucosal membranes of the trachea, along with petechial and necrotic haemorrhages of the proventriculus, were observed during the necropsy of the birds that died from the challenged virus. This study suggests that subsequent live virus vaccine by ocular route immunization is required to effectively protect against velogenic viscerotropic Newcastle disease infection. The results also highlight the importance of developing effective vaccination schedules and routes to enhance immunity against ND in layer chickens.

A Descriptive, Retrospective Analysis of COVID-19 Passive Antibody Therapy and Its Effects on Morbidity and Mortality in Patients Receiving B-Cell-Depleting Therapies.

Patients receiving B-cell-depleting therapies (BCDT) are at an increased risk for severe COVID-19. Passive antibody therapy (PAT), including COVID-19 convalescent plasma (CCP) and monoclonal antibodies (mAb), may be an effective treatment in this population. Real-world data on PAT effectiveness are limited. To evaluate response to PAT measured through 90-day all-cause morbidity and mortality, we performed a retrospective review of patients who contracted COVID-19 within a year from the last BCDT. From 64 included patients, the majority were Caucasians (95%), female (56%), vaccinated (67%), treated outpatients (64%), with multiple comorbidities. Examined BCDT were rituximab (55%), obinutuzumab (33%), ocrelizumab (11%) and ofatumumab (1%), used for underlying hematological malignancy (HEM) (40%), multiple sclerosis (34%), and rheumatoid arthritis (16%). Of seven deceased patients, three died from COVID-19. All three were elderly males with multiple comorbidities, treated inpatient for severe COVID-19. Four of 41 patients treated as outpatients were hospitalized for non-COVID-19-related reasons. All deceased and hospitalized patients had an underlying HEM. All but one were on rituximab. PAT may be an effective treatment for patients receiving BCDT, especially if given early for non-severe disease. Patients with underlying HEM may be at increased risk for severe disease compared with others receiving the same BCDT.

Longitudinal gut microbiota composition of South African and Nigerian infants in relation to tetanus vaccine responses.

Infants who are exposed to HIV but uninfected (iHEU) have higher risk of infectious morbidity than infants who are HIV-unexposed and uninfected (iHUU), possibly due to altered immunity. As infant gut microbiota may influence immune development, we evaluated the effects of HIV exposure on infant gut microbiota and its association with tetanus toxoid vaccine responses. We evaluated the gut microbiota of 82 South African (61 iHEU and 21 iHUU) and 196 Nigerian (141 iHEU and 55 iHUU) infants at <1 and 15 weeks of life by 16S rRNA gene sequencing. Anti-tetanus antibodies were measured by enzyme-linked immunosorbent assay at matched time points. Gut microbiota in the 278 included infants and its succession were more strongly influenced by geographical location and age than by HIV exposure. Microbiota of Nigerian infants, who were exclusively breastfed, drastically changed over 15 weeks, becoming dominated by Bifidobacterium longum subspecies infantis. This change was not observed among South African infants, even when limiting the analysis to exclusively breastfed infants. The Least Absolute Shrinkage and Selection Operator regression suggested that HIV exposure and gut microbiota were independently associated with tetanus titers at week 15, and that high passively transferred antibody levels, as seen in the Nigerian cohort, may mitigate these effects. In conclusion, in two African cohorts, HIV exposure minimally altered the infant gut microbiota compared to age and setting, but both specific gut microbes and HIV exposure independently predicted humoral tetanus vaccine responses.IMPORTANCEGut microbiota plays an essential role in immune system development. Since infants HIV-exposed and uninfected (iHEU) are more vulnerable to infectious diseases than unexposed infants, we explored the impact of HIV exposure on gut microbiota and its association with vaccine responses. This study was conducted in two African countries with rapidly increasing numbers of iHEU. Infant HIV exposure did not substantially affect gut microbial succession, but geographic location had a strong effect. However, both the relative abundance of specific gut microbes and HIV exposure were independently associated with tetanus titers, which were also influenced by baseline tetanus titers (maternal transfer). Our findings provide insight into the effect of HIV exposure, passive maternal antibody, and gut microbiota on infant humoral vaccine responses.

The Logic and History of Passive Immunity and Antibody Therapies.

This volume takes a broad overview of antibody-based therapies prior to and during the COVID pandemic and examines their potential use in future pandemics. Passive antibody therapy was the first effective antimicrobial treatment and its development in the early twentieth century helped catalyze immunological and microbiological research. During the era of serum therapy (1890-1940) antibody-based therapies were developed against both viral and bacterial diseases. Effective treatment required an understanding of how to quantify antibodies, how to develop serotype-specific sera and recognition of the need to treat early in disease. Thus, although the era of serum therapy essentially ended with the development of small molecule antimicrobial therapy in the 1940s, antibody-based therapies led to important new scientific understanding, while remaining in use for some toxin and venom-caused diseases and in the prevention of outbreaks of viral hepatitis. A renewed interest in antibody-based therapies was seen in the widespread deployment of convalescent plasma and monoclonal antibodies during the COVID-19 pandemic. Convalescent plasma will likely be the first specific therapy during outbreaks with new pathogens for which there is no other therapy. For all forms of antibody-based therapies, effectiveness relies on the key principles of antibody therapy, namely, treatment early in disease with preparations containing sufficient antibody specific to the microbe in question.

Monoclonal Antibodies and Hyperimmune Immunoglobulins in the Next Pandemic.

Pandemics are highly unpredictable events that are generally caused by novel viruses. There is a high likelihood that such novel pathogens belong to entirely novel viral families for which no targeted small-molecule antivirals exist. In addition, small-molecule antivirals often have pharmacokinetic properties that make them contraindicated for the frail patients who are often the most susceptible to a novel virus. Passive immunotherapies-available from the first convalescent patients-can then play a key role in controlling pandemics. Convalescent plasma is immediately available, but if manufacturers have fast platforms to generate marketable drugs, other forms of passive antibody treatment can be produced. In this chapter, we will review the technological platforms for generating monoclonal antibodies and hyperimmune immunoglobulins, the current experience on their use for treatment of COVID-19, and the pipeline for pandemic candidates.

Protective antibody concentrations in primary immunodeficiency following infusion with 5% or 10% intravenous immunoglobulin.

Inadequate production of immunoglobulin G (IgG) antibodies renders patients with primary immunodeficiencysusceptible to infection by numerous pathogens, some of which can lead to severe asthma exacerbation and possible death. These patients who are immunocompromised are often reliant on intravenous immunoglobulin (IVIG) therapies, which provide passive antibodies against various respiratory pathogens, including measles virus and encapsulated bacteria. We conducted a subanalysis of data from a multicenter, multinational, phase III, open-label bioequivalencestudy to compare protective concentrations of IgG antibodies provided by a 5% and a 10% IVIG product in patients with primaryimmunodeficiency. Patients on stable 21- or 28-day regimens of previous IVIG products were assigned to receive study treatment (adults: 5% IVIG and 10% IVIG; children: 10% IVIG) at doses of 300-800 mg/kg per infusion. Trough concentrations of total IgG, IgG subclasses, measles-neutralizing antibodies, and IgG against Haemophilus influenzae type b and Streptococcus pneumoniae serotypes were evaluated. A total of 48 patients (33 adults ages 16-55 years; 15 children ages 2-15 years) were enrolled and received treatment.No statistically significant differences in trough concentrations of total IgG, IgG subclasses, measles neutralizing antibodies, or IgG directed at encapsulated bacteria were observed between the 5% and 10% formulations in analyses by age (adult or pediatric) or infusion schedule (every 21 or 28 days). All evaluated patients had trough IgG concentrations above accepted thresholds for protection against disease. These findings support the conclusion that, at dose levels and infusion schedules prescribed in clinical practice,this 5% and 10% IVIG product provided consistent, predictable, and bioequivalent IgG concentrations for adult and pediatricpatients with primary immunodeficiency disease. Both formulations delivered trough antibody concentrations of total IgG, measles- neutralizing antibodies, and antibodies against encapsulated bacteria that are above thresholds accepted as protective.

Role of Pre-Farrow Natural Planned Exposure of Gilts in Shaping the Passive Antibody Response to Rotavirus A in Piglets.

Natural planned exposure (NPE) remains one of the most common methods in swine herds to boost lactogenic immunity against rotaviruses. However, the efficacy of NPE protocols in generating lactogenic immunity has not been investigated before. A longitudinal study was conducted to investigate the dynamics of genotype-specific antibody responses to different doses (3, 2 and 1) of Rotavirus A (RVA) NPE (genotypes G4, G5, P[7] and P[23]) in gilts and the transfer of lactogenic immunity to their piglets. Group 1 gilts received three doses of NPE at 5, 4 and 3 weeks pre-farrow (WPF), group 2 received two doses at 5 and 3 WPF, group 3 received one dose at 5 WPF, and group 4 received no NPE (control group). VP7 (G4 and G5) and truncated VP4* (P[7] and P[23]) antigens of RVA were expressed in mammalian and bacterial expression systems, respectively, and used to optimize indirect ELISAs to determine antibody levels against RVA in gilts and piglets. In day-0 colostrum samples, group 1 had significantly higher IgG titers compared to the control group for all four antigens, and either significantly or numerically higher IgG titers than groups 2 and 3. Group 1 also had significantly higher colostrum IgA levels than the control group for all antigens (except G4), and either significantly or numerically higher IgA levels compared to groups 2 and 3. In piglet serum, group 1 piglets had higher IgG titers for all four antigens at day 0 than the other groups. Importantly, RVA NPE stimulated antibodies in all groups regardless of the treatment doses and prevented G4, G5, P[7] and P[23] RVA fecal shedding prior to weaning in piglets in the absence of viral challenge. The G11 and P[34] RVA genotypes detected from pre-weaning piglets differed at multiple amino acid positions with parent NPE strains. In conclusion, the results of this study suggest that the group 1 NPE regimen (three doses of NPE) resulted in the highest anti-RVA antibody (IgG and IgA) levels in the colostrum/milk, and the highest IgG levels in piglet serum.