Prevalence Of Neutralizing Antibodies Research Articles

Haemovigilance survey and screening strategy for arthropod-borneviruses in blood donors from Argentina.

Arthropod-borne viruses (arboviruses) count among emerging infections, which represent a major challenge for transfusion safety worldwide. To assess the risk of arboviruses-transmission by transfusion (ATT), we performed a survey to evaluate the potential threat for transfusion safety. Samples were retrospectively and randomly collected from donors who donated during the peak of dengue incidence in Cordoba (years: 2016and 2019-2022). A cost-efficient strategy for molecular screening was implemented with a nucleic acid test (NAT) configured with Flavivirus and Alphavirus-universal degenerated primers targeting conserved gene regions. Besides, we evaluated the neutralizing antibody (NAb) prevalence by plaque reduction neutralization test (PRNT). A total of 1438 samples were collected. Among the NAT-screened samples, one resulted positive for Flavivirus detection. Subsequent sequencing of the PCR product revealed Saint Louis Encephalitis Virus (SLEV) infection (GeneBank accession number OR236721). NAb prevalence was 2.95% for anti-Dengue, 9.94% anti-SLEV, 1.09% anti-West Nile Virus, and 0% anti-Chikungunya. One of the NAb-positive samples also resulted positive for IgM against SLEV but negative by ARN detection. This is the first haemovigilance study developed in Argentina that evaluates the potential risk of ATT and the first research to determine the prevalence of NAb against Flavivirus through PNRT to avoid possible cross-reactions between Ab against Flavivirus. Herein, the finding of one SLEV-viremic donor and the detection of anti-SLEV IgM in a different donor demonstrated a potential threat for transfusion safety and emphasized the need for increased vigilance and proactive measures to ensure the safety of blood supplies.

Low prevalence of anti‐Orthopoxvirus neutralizing antibodies in an urban population of Brazil

AbstractSince 1999, Vaccinia virus (VACV) has been described as a causative agent of bovine vaccinia (BV), a zoonotic disease that occurs mainly in rural areas of Brazil. However, the circulation of VACV in urban environments and its associated burden has been poorly explored. Moreover, the current monkeypox (mpox) outbreak has raised questions regarding the immune status of the worldwide population previous vaccinated against smallpox. Hence, we conducted a cross‐sectional study to better understand the prevalence of anti‐OPV neutralizing antibodies (NA) and related exposure factors in a susceptible urban population of Brazil. A total of 372 individuals were sampled, yielding an overall seroprevalence of 16.9% (CI95% = 13.4–21.1), and antibodies titers ranging from 100 to 800 neutralizing units/mL. The prevalence of NA among individuals potentially vaccinated against smallpox (≥36 years old [yo]) was 24.9% (IC 95% = 19.5–31.2), and among those unvaccinated (<36yo) was 6.7% (IC 95% = 3.7–11.8). Interestingly, contact with horses was pointed out as an exposure factor for the presence of NA, however, the multivariate logistic regression analysis indicated that age ≥36yo and the presence of vaccine take were independently associated with the presence of anti‐OPV NA. Our findings suggest that vulnerable populations could be subclinically exposed to VACV in urban areas, drawing attention to alternative routes of zoonotic VACV exposure. Our data is also important for better strategies to mitigate zoonotic OPV infections mainly among vulnerable populations.

Prevalence of Neutralizing Antibodies against Adeno-Associated Virus Serotypes 1, 2, and 9 in Non-Injected Latin American Patients with Heart Failure—ANVIAS Study

Neutralizing antibody (NAb) activity against the viral capsid of adeno-associated viral (AAV) vectors decreases transduction efficiency, thus limiting transgene expression. Several reports have mentioned a variation in NAb prevalence according to age, AAV serotype, and, most importantly, geographic location. There are currently no reports specifically describing the anti-AAV NAb prevalence in Latin America. Here, we describe the prevalence of NAb against different serotypes of AAV vectors (AAV1, AAV2, and AAV9) in Colombian patients with heart failure (HF) (referred to as cases) and healthy individuals (referred to as controls). The levels of NAb were evaluated in serum samples of 60 subjects from each group using an in vitro inhibitory assay. The neutralizing titer was reported as the first dilution inhibiting ≥50% of the transgene signal, and the samples with neutralizing titers at ≥1:50 dilution were considered positive. The prevalence of NAb in the case and control groups were similar (AAV2: 43% and 45%, respectively; AAV1 33.3% in each group; AAV9: 20% and 23.2%, respectively). The presence of NAb for two or more of the serotypes analyzed was observed in 25% of the studied samples, with the largest amount in the positive samples for AAV1 (55-75%) and AAV9 (93%), suggesting serial exposures, cross-reactivity, or coinfection. Moreover, patients in the HF group exhibited more common combined seropositivity for NAb against AAV1 d AAV9 than those in the control group (91.6% vs. 35.7%, respectively; p = 0.003). Finally, exposure to toxins was significantly associated with the presence of NAb in all regression models. These results constitute the first report of the prevalence of NAb against AAV in Latin America, being the first step to implementing therapeutic strategies based on AAV vectors in this population in our region.

Seroprevalence of Binding and Neutralizing Antibodies against 39 Human Adenovirus Types in Patients with Neuromuscular Disorders.

High pre-existing antibodies against viral vectors reduce their functionality and may lead to adverse complications. To circumvent this problem in future gene therapy approaches, we tested the seroprevalence of a large range of human adenovirus types in patients with neuromuscular disorders (NMDs) to find appropriate viral vector candidates for gene replacement therapy for NMDs. Binding and neutralizing antibodies against 39 human adenovirus types were tested in the sera of 133 patients with NMDs and 76 healthy controls aged 17-92 years. The influence of age, sex, and NMDs on antibody levels was analyzed. The seroprevalence of different adenoviruses in the cohort varied widely. The highest levels of binding antibodies were detected against HAdV-D27, -C1, -D24, -D70, -B14, -C6, -D13, -B34, and -E4, whereas the lowest reactivity was detected against HAdV-F41, -A31, -B11, -D75, -D8, -D65, -D26, -D80, and -D17. The highest neutralizing reactivity was observed against HAdV-B3, -C2, -E4, -C1, -G52, -C5, and -F41, whereas the lowest neutralizing reactivity was observed against HAdV-D74, -B34, -D73, -B37, -D48, -D13, -D75, -D8, -B35, and -B16. We detected no influence of sex and only minor differences between different age groups. Importantly, there were no significant differences between healthy controls and patients with NMDs. Our data show that patients with NMDs have very similar levels of binding and neutralizing antibodies against HAdV compared to healthy individuals, and we identified HAdV-A31, -B16, -B34, -B35, -D8, -D37, -D48, -D73, -D74, -D75, and -D80 as promising candidates for future vector development due to their low binding and neutralizing antibody prevalence.

Seroepidemiological and genomic investigation of SARS-CoV-2 spread in North East region of India

PurposeSeroepidemiology and genomic surveillance are valuable tools to investigate infection transmission during a pandemic. North East (NE) India is a strategically important region being the gateway connecting the country with Southeast Asia. Here, we examined the spread of SARS-CoV-2 in NE India during the first and second waves of COVID-19 using serological and whole genome sequencing approaches. MethodsqRT-PCR analysis was performed on a selected population (n ​= ​16,295) from June 2020 to July 2021, and metadata was collected. Immunoassays were studied (n ​= ​2026) at three-time points (August 2020, February 2021, and June 2021) and in a cohort (n ​= ​35) for a year. SARS-CoV-2 whole genomes (n ​= ​914) were sequenced and analyzed with those obtained from the databases. ResultsTest positivity rates (TPR) in the first and second waves were 6.34% and 6.64% in Assam, respectively, and a similar pattern was observed in other NE states. Seropositivity in the three time points was 10.63%, 40.3%, and 46.33%, respectively, and neutralizing antibody prevalence was 90.91%, 52.14%, and 69.30%, respectively. Persistence of pan-IgG-N SARS-CoV-2 antibody for over a year was observed among three subjects in the cohort group. Normal variants dominated the first wave, while B.1.617.2 and AY-sublineages dominated the second wave in the region. The prevalence of the variants co-related well with high TPR and seropositivity rate in the region and identified mostly among vaccinated individuals. ConclusionThe COVID-19 first wave in the region witnessed low transmission with the evolution of diverse variants. Seropositivity increased during the study period with over half of the individuals carrying neutralizing antibodies against SARS-CoV-2. High infection and seroprevalence in NE India during the second wave were associated with the dominant emergence of variants of concern.

Significantly lower antigenicity of incobotulinumtoxin than abo- or onabotulinumtoxin

BackgroundFor many indications, BoNT/A is repetitively injected with the risk of developing neutralizing antibodies (NABs). Therefore, it is important to analyze whether there is a difference in antigenicity between the different licensed BoNT/A preparations.MethodsIn this cross-sectional study, the prevalence of NABs was tested by means of the sensitive mouse hemidiaphragm assay (MHDA) in 645 patients. Patients were split into those having exclusively been treated with the complex protein-free incoBoNT/A preparation (CF-MON group) and those having started BoNT/A therapy with a complex protein-containing BoNT/A preparation (CC-I group). This CC-I group was split into those patients who remained either on abo- or onaBoNT/A (CC-MON group) and those who had been treated with at least two BoNT/A preparations (CC-SWI group). To balance treatment duration, only CC-MON patients who did not start their BoNT/A therapy more than 10 years before recruitment (CC-MON-10 group) were further analyzed. The log-rank test was used to compare the prevalence of NABs in the CF-MON and CC-MON-10 group.ResultsIn the CF-MON subgroup, no patient developed NABs. In the CC-I group, 84 patients were NAB-positive. NABs were found in 33.3% of those who switched preparations (CC-SWI) and in 5.9% of the CC-MON-10 group. Kaplan–Meier curves for remaining NAB-negative under continuous BoNT/A therapy were significantly different (p < 0.035) between the CF-MON and CC-MON-10 group.ConclusionFrequent injections of a complex protein-containing BoNT/A preparation are associated with significantly higher risks of developing NABs than injections with the same frequency using the complex protein-free incoBoNT/A preparation.

An epidemiological study to determine demographic factors influencing COVID-19 IgG antibody production among the adult population of urban area in Malegaon, Maharashtra - A cross sectional study

Background: Seroprevalence of COVID-19 antibody production in a person can be dependent on many physiological and demographic aspects such as previous infection, age, sex, body mass index, and also status of vaccination. It is of immense value to know about demographic aspect of COVID-19 antibody production so as to know about vulnerable population and suggest preventive measures. Aims and Objectives: The present study was aimed to determine effect of demographic variables COVID-19 antibody production in population of urban area. Materials and Methods: In this study, a total of 2454 subjects were screened for COVID-19 neutralizing antibody by ELISA technique. Subjects more than 18-year-old were selected for the study. We used cluster sampling method for data collection. A pre-structured questionnaire was administered after informed consent and 5 mL venous blood was collected in plain bulb for testing. Results: The prevalence of neutralizing antibody was found to be 93.9%. Female had 95% positive antibodies against males (92.34%). Maximum positive antibody status was seen in age group of 20–40 (55.6%). About 77.9% subjects following mixed diet were having positive COVID-19 antibody test as compared to subjects following pure vegetarian (10.2%). About 83.2% subjects who received vaccine showed positive antibody test. The lowest positivity is seen in underweight subjects (8%) followed by obese subjects (12.7%). Maximum inhibition % was seen in subjects using Vitamin C Zinc tablets (92.1%). The lowest inhibition was seen in subjects using Unani Kadha. A one-way ANOVA revealed that there was not a statistically significant difference in prophylactic measures for prevention of COVID-19 infection other than vaccination and COVID-19 neutralizing antibody inhibition %. ([F-1.363], P=0.244). Conclusion: COVID-19 neutralizing antibody prevalence was found to be much higher in the population (96%), which was mostly associated with younger age, gender, diet, and vaccination status of the population. Extensive studies are required to establish any association between prophylactic methods other than vaccination and COVID-19 antibody response.

Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong

Monitoring population protective immunity against SARS-CoV-2 variants is critical for risk assessment. We hypothesize that Hong Kong’s explosive Omicron BA.2 outbreak in early 2022 could be explained by low herd immunity. Our seroprevalence study using sera collected from January to December 2021 shows a very low prevalence of neutralizing antibodies (NAb) against ancestral virus among older adults. The age group-specific prevalence of NAb generally correlates with the vaccination uptake rate, but older adults have a much lower NAb seropositive rate than vaccination uptake rate. For all age groups, the seroprevalence of NAb against Omicron variant is much lower than that against the ancestral virus. Our study suggests that this BA.2 outbreak and the exceptionally high case-fatality rate in the ≥80 year-old age group (9.2%) could be attributed to the lack of protective immunity in the population, especially among the vulnerable older adults, and that ongoing sero-surveillance is essential.

Age-stratified adeno-associated virus serotype 3 neutralizing and total antibody prevalence in hemophilia A patients from India.

Gene therapy using an adeno-associated virus (AAV) vector offers a new treatment option for individuals with monogenetic disorders. The major bottleneck is the presence of pre-existing anti-AAV antibodies, which impacts its use. Even very low titers of neutralizing antibodies (NAb) to capsids from natural AAV infections have been reported to inhibit the transduction of intravenously administered AAV in animal models and are associated with limited efficacy in human trials. Assessing the level of pre-existing NAb is important for determining the primary eligibility of patients for AAV vector-based gene therapy clinical trials. Techniques used to screen AAV-antibodies include AAV capsid enzyme-linked immunosorbent assay(ELISA) and transduction inhibition assay (TIA) for detecting total capsid-binding (TAb) and Nab, respectively. In this study, we screened 521 individuals with hemophilia A from India for TAb and NAb using ELISA and TIA, respectively. The prevalence of TAb and NAb in hemophilia A patients from India were 96% and 77.5%, respectively. There was a significant increase in anti-AAV3 NAb prevalence with age in the hemophilia A patient group from India. There was a trend in anti-AAV3 TAb positivity between the pediatric age group (94.4%) and the adult age group (97.4%).

Directed evolution of adeno-associated virus 5 capsid enables specific liver tropism

Impressive achievements in clinical trials to treat hemophilia establish a milestone in the development of gene therapy. It highlights the significance of AAV-mediated gene delivery to liver. AAV5 is a unique serotype featured by low neutralizing antibody prevalence. Nevertheless, its liver infectivity is relatively weak. Consequently, it is vital to exploit novel AAV5 capsid mutants with robust liver tropism. To this aim, we performed AAV5-NNK library and barcode screening in mice, from which we identified one capsid variant, called AAVzk2. AAVzk2 displayed a similar yield but divergent post-translational modification sites compared with wild-type serotypes. Mice intravenously injected with AAVzk2 demonstrated a stronger liver transduction than AAV5, roughly comparable with AAV8 and AAV9, with undetectable transduction of other tissues or organs such as heart, lung, spleen, kidney, brain, and skeletal muscle, indicating a liver-specific tropism. Further studies showed a superior human hepatocellular transduction of AAVzk2 to AAV5, AAV8 and AAV9, whereas the seroreactivity of AAVzk2 was as low as AAV5. Overall, we provide a novel AAV serotype that facilitates a robust and specific liver gene delivery to a large population, especially those unable to be treated by AAV8 and AAV9.

Botulinum Toxin Type A Immunogenicity across Multiple Indications: An Overview Systematic Review.

Botulinum toxin type A has been used to treat a wide array of neurologic, medical, and aesthetic indications. Several factors contribute to the formation of neutralizing antibodies, such as shorter intervals of treatment, higher dosage, amounts of antigenic proteins, serotypes, and storage of formulations. This overview followed the Cochrane guideline for overview reviews. The AMSTAR-2 (revised version of A Measurement Tool to Assess Systematic Reviews) tool was used for the critical appraisal of the selected systematic reviews. Five systematic reviews consisting of 203 studies (17,815 patients) were included, and their AMSTAR-2 scores were low to critically poor. There was high heterogeneity between the studies. Across the clinical indications, neutralizing antibody prevalence was significantly higher in dystonia, spasticity, and urologic conditions, and nil to insignificant in hyperhidrosis and aesthetic indications. The overall rate for the neutralizing antibody formation across three different formulations, abobotulinumtoxinA, incobotulinumtoxinA, and onabotulinumtoxinA, was 1 to 2.1 percent, with no significant difference between them. Although there is debate on the prevalence rate across the different botulinum toxin type A formulations in individual systematic reviews, the overall frequency of the development of neutralizing antibodies and the immunogenicity of abobotulinumtoxinA, incobotulinumtoxinA, and onabotulinumtoxinA remain low to insignificant. Properly designed comparative trials are required to explore the difference in the prevalence of neutralizing antibodies across the commercially available botulinum toxin type A products. Such studies should also examine the relevance of neutralizing antibody titer to clinical responsiveness and nonresponse.

West Nile virus neutralizing antibody prevalence in donkeys from northern Nigeria.

This study aimed to evaluate the prevalence of anti-West Nile virus (WNV) neutralizing antibodies in donkeys from two areas in northern Nigeria. Serology was determined by a virus neutralization test in samples collected from 205 healthy adult donkeys. Fifty-seven donkeys (27.8%) tested seropositive for WNV. Donkeys from Zaria were 2.6 times more likely to have been exposed to WNV (p<0.001). The results of this study demonstrate that this zoonotic pathogen is prevalent in these areas and that measures should be implemented to reduce the risk for both humans and equids.

Seroprevalence of Pre-Existing Nabs Against AAV1, 2, 5, 6 and 8 in South African Hemophilia B Patient Population

Introduction Several studies have shown that the induction of antibodies by natural exposure to various AAV serotypes can compromise the subsequent use of AAV as a gene therapy vector, limiting patient eligibility for AAV-delivered therapeutics. The implications of pre-existing antibodies to AAV serotypes are very different: Levels of anti-AAV2 or anti-AAV8 neutralizing antibodies (NABs) as low as 5 have been related to a decrease or even total impairment of AAV liver transduction after systemic delivery in humans. However, successful gene transfer has been reported in patients with anti-AAV5 NABs titers up to 340 and in non-human primates with titers up to 1030. Extensive surveys on the prevalence of anti-AAV antibodies in humans have been published. Results from these studies indicate that prevalence varies dependent on serotype, and that a significant proportion of individuals develop humoral immunity against various AAV serotypes early in life, starting around 2 years of age. Furthermore, the prevalence of antibodies to different AAV serotypes has been reported to vary according to geographical location. Study Objective We performed a NABs seroprevalence study in South African hemophilia B patient population (n=44) using a panel of AAV serotypes suitable for liver targeted therapy, to determine the AAV serotypes likely to be of greatest clinical applicability for the South African hemophilia B population. Methods Forty-four hemophilia B patient serum samples were obtained from Hemophilia Comprehensive Care Center in Johannesburg (South Africa). All the patient serum samples were analyzed for the presence of NABs against AAV serotypes 1, 2, 5, 6 and 8 with the use of highly sensitive luciferase-based bioassays. The assays entail incubation of the test serum samples dilution series with an AAV1, 2, 5, 6 or 8-based reporter vector that carries the luciferase gene. This incubation allows neutralizing antibodies in the test serum to bind to the reporter vector particles. These mixtures are subsequently transferred onto Hek293T cells, where reporter vector particles can transduce cells and mediate expression of luciferase. Anti-AAV1, 2, 5, 6 or 8 NABs titers were determined by calculation of the percentage of neutralization for each sample dilution and fitting the neutralization curve with a four-parameter method. Anti-AAV1, 2, 5, 6 or 8 NABs titer (IC50) is the dilution at which antibodies inhibit Hek293T cell transduction with AAV1, 2, 5, 6 or 8-LUC by 50%. The lowest patient serum dilution used in every assay was 8 and samples were considered positive when calculated anti-AAV NAB titer was ≥8. All analytical runs included proper negative and positive controls. Results and Discussion The presence of NABs against the AAV serotypes 1, 2, 5, 6 and 8 was determined in the serum of the hemophilia B patients (Fig. 1). The highest prevalence of NABs was found to be against the AAV2 serotype, 95% (n=42/44) followed by the AAV6 serotype, 82% (n=36/44), and the AAV1 serotype 77% (n=34/44). The prevalence of NABs against AAV5 and AAV8 was lower with 66% (n=29/44) for AAV5 and 64% (n=28/44) for AAV8. The serum samples positive for anti-AAV2 NABs had a high occurrence of titers above 1030 (39%) in comparison to anti-AAV1 NABs (20%), anti-AAV5 NABs (5%) or anti-AAV8 NABs (7%).The occurrence of samples with low titers (ranging from titer of 8 to titer of 50) was the highest for anti-AAV8 NABs (32%) and for anti-AAV5 NABs (27%), followed by anti-AAV2 (18%) and anti-AAV1 (5%) (Fig.1). Currently, an anti-AAV NABs titer of 5 is used as an exclusion criteria in most of the systemic AAV-based gene therapies. When applying a similar cut-off of 8, 23% of the analyzed patients could be treated with AAV1, 5% with AAV2, 34% with AAV5, 18% with AAV6 and 36% with AAV8-based therapeutics (Fig.2). However, we have previously reported that AAV5-neutralizing antibodies do not impair the efficacy of in vivo transduction of AAV5-based vector up to a measured titer of 340 in humans and 1030 in non-human primates. Therefore, applying the cut-off of 340 or 1030, either 84% or 95% of the South African Hemophilia B patients could benefit from treatment with AAV5-based gene therapy (Fig.2). Disclosures Majowicz: uniQure N.V.: Employment. van Waes:uniQure N.V.: Employment. Timmer:uniQure N.V.: Employment. van Deventer:uniQure Biopharma B.V.: Employment. Mahlangu:Takeda: Consultancy, Honoraria, Speakers Bureau; LFB: Consultancy; NovoNordisk: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Baxalta: Consultancy, Research Funding, Speakers Bureau; Freeline Therapeutics: Research Funding; Pfizer: Consultancy, Research Funding, Speakers Bureau; Spark: Consultancy, Speakers Bureau; Chugai: Consultancy; Biomarin: Research Funding; CSL Behring: Consultancy, Research Funding, Speakers Bureau; Novartis: Research Funding; Sanofi Genzyme: Research Funding, Speakers Bureau; Shire: Consultancy, Research Funding, Speakers Bureau; Sobi: Research Funding, Speakers Bureau; uniQure: Research Funding; World Federation of Haemophilia: Speakers Bureau. Ferreira:uniQure N.V.: Employment.

Author response: High prevalence of neutralizing antibodies after long-term botulinum neurotoxin therapy.

Author response: High prevalence of neutralizing antibodies after long-term botulinum neurotoxin therapy.

Author response: High prevalence of neutralizing antibodies after long-term botulinum neurotoxin therapy.

Author response: High prevalence of neutralizing antibodies after long-term botulinum neurotoxin therapy.

Reader response: High prevalence of neutralizing antibodies after long-term botulinum neurotoxin therapy.

We read with interest the article by Albrecht et al.,1 which demonstrated that 14% of 596 patients treated with various botulinum toxin (BoNT) preparations over 2–5 years developed neutralizing antibodies (Nabs).

Immunogenicity induced by botulinum toxin injections for limb spasticity: A systematic review.

The imputability of neutralizing antibodies (NABs) in secondary non-response (SnR) to botulinum toxin (BoNT) injections for limb spasticity is still debated. This systematic literature review aimed to determine the prevalence of NABs after BoNT injections for limb spasticity and analyze their determinants and their causal role in SnR. We searched MEDLINE via PubMed, Cochrane and Embase databases for articles published during 1990-2018. Two independent reviewers extracted the data and assessed the quality of studies with a specific scale (according to PRISMA and STROBE guidelines). Because the techniques used to detect NABs did not influence the results, we calculated the global (all studies) sensitivity and specificity of NAB positivity to reveal SnR. We included 14 articles published from 2002 to 2018 (including an epublication) describing 5 randomized controlled trials and 5 interventional and 4 observational studies. The quality was satisfactory (mean score 18/28 arbitrary units). NAB detection was the primary criterion in 5 studies and a secondary criterion in 9. In total, 1234 serum samples for 1234 participants (91% with stroke) were tested after injection. NAB prevalence was about 1%, with no significant difference among formulations. NAB positivity seemed favoured by long-duration therapy with high doses and a short interval between injections. The identification of non-response by NAB positivity had poor global sensitivity (56%) but very high specificity (99.6%). No consensual criteria were used to diagnose non-response to BoNT injection. NAB prevalence is much lower after BoNT treatment for limb spasticity than cervical dystonia. Consensual criteria must be defined to diagnose non-response to BoNT injection. Because immunogenicity is not the most common cause of non-response to BoNT injection, NABs should be sought in individuals with SnR with no other cause explaining the treatment inefficacy. A test with 100% specificity is recommended. In cases for which immunogenicity is the most likely cause of non-response to BoNT injections, some biological arguments suggest trying another BoNT, but no clinical evidence supports this strategy.

Pre-existing antibodies to candidate gene therapy vectors (adeno-associated vector serotypes) in domestic cats.

Adeno-associated virus (AAV) vectors represent promising candidates for gene therapy; however, pre-existing neutralizing antibodies (NAb) may reduce AAV vector delivery efficiency. In this study, the presence of AAV NAb was investigated in cats, which serve as a larger and outbred animal model for the prediction of gene therapy outcomes in humans but also in cats.Serum/plasma samples from 230 client-owned Swiss cats and 20 specified pathogen-free cats were investigated for NAb to AAV1, AAV2, AAV5, AAV6, AAV7, AAV8 and AAV9 using in vitro transduction inhibition and a beta-galactosidase assay. NAb to all tested AAV serotypes were found. Of the client-owned cats, 53% had NAb to one or more of the AAV serotypes. NAb (≥1:10) were found at frequencies of 5% (AAV6) to 28% (AAV7). The highest titers were found against AAV7 (≥1:160). The NAb prevalence to AAV2, AAV7 and AAV9 differed geographically. Regarding titers ≥1:10 against single AAV serotypes, age, breed and sex of the cats were not associated with the NAb prevalence. Cats with titers ≥1:20 against AAV2 and titers ≥1:40 against AAV7 were significantly younger than cats with low/no titers, and purebred cats were significantly more likely than non-purebred cats to have NAb to AAV2 (≥1:40). Additionally, regarding NAb to all AAV combined, female cats were significantly more likely than male cats to have NAb titers ≥1:40. Preliminary data using AAV-DJ indicated that less pre-existing NAb to the hybrid AAV-DJ can be expected compared to the wild-type AAV serotypes. AAV NAb will need to be taken into account for future in vivo gene therapy studies in cats.

Seroepidemiology of Parechovirus A3 Neutralizing Antibodies, Australia, the Netherlands, and United States

Recent parechovirus A3 (PeV-A3) outbreaks in Australia suggest lower population immunity compared with regions that have endemic PeV-A3 circulation. A serosurvey among populations in the Netherlands, the United States, and Australia before and after the 2013 Australia outbreak showed high PeV-A3 neutralizing antibody prevalence across all regions and time periods, indicating widespread circulation.

Differential Immune Responses in Epidemic and Endemic Tanzanian Kaposi Sarcoma Patients

Background: Mechanisms underlying Kaposi sarcoma (KS) development are unclear. The high incidence of KS in HIV-1+ individuals implicates immune dysregulation in epidemic KS (EpKS) development. In African endemic KS (EnKS), the immune response is uncharacterized. Aim: The aim was to assess a comparative quantification between newly diagnosed Tanzanian EpKS and EnKS patients, and asymptomatic controls. We also report the first comparison of KSHV NAb prevalence and titer between EpKS and EnKS patients. Methods: To compare innate and adaptive immune responses, we recruited histologically confirmed Tanzanian EpKS and EnKS patients, as well as noncancer controls. After differential detection of KSHV nucleic acids in tissues, neutralizing antibody (NAb), levels of cytokines/chemokines, and T-cell differentiation subsets were quantified. The Mann-Whitney U-test was used to assess median differences between groups. All tests were 2-tailed and P-values &lt; 0.05 were considered significant. Results: A total of 180 patients have been recruited in this study. In addition, a comparable 25 EpKS and 10 EnKS as well as 10 noncancer controls were recruited for this study. KSHV was significantly more frequently detected in EpKS patients than in EnKS. While all EpKS, and some EnKS patients mounted NAb responses, the EpKS patients had higher prevalence and titer of NAb compared with EnKS patients ( P = 0.001). Levels of the cytokines IP-10 and IL-10 were higher in EpKS vs EnKS patients ( P = 0.006 and P = 0.005 respectively), whereas, IL-4 was lower in EpKS vs EnKS patients ( P = 0.004). The levels of all 14 cytokines/chemokines measured were comparable between EnKS patients and HIV− controls ( P &lt; .05 ). The distribution of CD4+ and CD8+ T-cells was similar between EpKS and EnKS such as naive and effector T-cells were depleted while central memory T-cells were elevated in both KS forms. Conclusion: The detection of similar abnormalities in T-cell differentiation subsets in both EpKS and EnKS as compared with controls, suggests that KSHV-induced T-cell dysfunction plays a major role in the disease, and that HIV-1 coinfection is only exacerbating and accelerating KSHV pathogenesis and KS development.