Search Results (71)

Respiratory syncytial virus (RSV) remains a major cause of severe lower respiratory tract infection in early infancy, a period characterized by immunological immaturity and limited capacity for effective antiviral responses. Maternal RSV vaccination has emerged as a successful strategy to protect newborns by inducing high concentrations of IgG1-dominant, prefusion F-specific antibodies, which are selectively and actively transported across the placenta. This review synthesizes current mechanistic insights into how maternally derived antibodies confer neonatal protection, focusing on (i) FcRn-mediated transplacental transport, (ii) IgG subclass-specific differences in transfer and half-life, and (iii) the role of Fc glycosylation in modulating Fcγ receptor engagement and effector functions. Beyond neutralization, vaccine-induced antibodies mediate Fc-dependent mechanisms such as antibody-dependent cellular cytotoxicity and phagocytosis, which may be preferentially enriched in the neonatal circulation. Although emerging systems serology data suggest qualitative selectivity in placental transfer, evidence remains heterogeneous and highlights the need for further clarification of glycosylation-dependent and glycosylation-independent pathways. The timing of vaccination, maternal antibody characteristics, and placental integrity critically influence neonatal antibody levels and the duration of passive immunity. Understanding these molecular determinants is essential for optimizing maternal RSV immunization strategies and improving early-life protection. Full article

Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are regarded as the most clinically and economically important avian Mycoplasma species, posing significant challenges to the poultry industry worldwide. In this study, MG and MS antibodies were detected by ELISA in 857 unvaccinated Chinese native chickens from 21 breeder flocks on four multi-age farms. The overall seropositive rates were 86.3% for MG and 98.4% for MS. Offspring from an infected breeder flock were reared under different environmental conditions, and serological monitoring was conducted over a 68-week production cycle. The antibody titers and seropositive rates of both mycoplasmas in birds reared in an isolation room were significantly lower than those in birds reared on the farm after maternal antibodies vanished. By adopting strict biosecurity measures, MG and MS infections were effectively controlled in an offspring flock derived from infected breeders, as evidenced by a substantial decrease in seropositive rates. The results suggested that MG and MS infections were prevalent in the breeder flocks of Chinese native chickens. Horizontal rather than vertical infection was the primary cause of high flock infection levels under field conditions. Strict biosecurity measures could be adopted to initially control MG and MS infections in offspring from the breeder flocks with high infection levels. Full article

Neonatal defense against pathogens relies on maternal antibodies transferred both through the placenta (IgG) and through breast milk (primarily secretory IgA). Maternal IgG antibodies are transferred across the placenta to the fetus mainly via the neonatal Fc receptor (FcRn), which is expressed at high levels in placental syncytiotrophoblasts, and results in the acquisition of maternal-fetal IgG. Transplacental transfer via the FcRn pathway can provide therapeutic proteins and protective antibodies following maternal vaccination. However, maternal IgG antibodies can bind to vaccine antigens such as measles, tetanus, and poliovirus, resulting in rapid clearance through FcgRIIB-mediated inhibition and inadequate B cell activation. In this way, they can inhibit de novo immune responses and significantly reduce vaccine response. On the other hand, the interference that breast milk-derived antibodies may have on vaccine-induced immunity is still largely unknown. Vaccination against influenza, pertussis, and COVID-19 during pregnancy or lactation has been shown to induce the production of protective, pathogen-specific, secretory IgA and IgG antibodies in breast milk. Conversely, studies found that breast milk-derived antibodies of vaccinated mothers reduced vaccine-induced immunity in breastfed infants by accelerating the clearance of vaccine antigen, resulting in reduced antigen availability and reduced plasma cell formation after vaccination. Additional factors in middle- and low-income countries, including environmental (increased microbiome diversity, environmental intestinal dysfunction, malnutrition, co-infections) and breastfeeding practices, may exacerbate the interference effect of maternal antibodies. Current evidence supports that breastfeeding is associated with a reduced immunological response exclusively to the rotavirus vaccine. However, the limited evidence base to date precludes definitive conclusions regarding the role of breast milk-derived antibodies in modulating vaccine-induced immunity. Nevertheless, the evidence suggests that although maternal antibodies may theoretically reduce vaccine immunogenicity, the overall protective benefits of breastfeeding outweigh any potential interference with vaccine responses. Full article

Porcine enteric coronaviruses (PECs), including porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine deltacoronavirus (PDCoV), and swine acute diarrhea syndrome coronavirus (SADS-CoV), remain major causes of neonatal diarrhea, dehydration, mortality, and economic loss in swine production. Despite substantial progress in vaccine development, durable field protection is still inconsistent. In this narrative review, this narrative review synthesizes current knowledge on PEC vaccine design from three connected perspectives: antigenic breadth, mucosal immunity, and translational evaluation. The economic and virological context of PEC vaccine development is first summarized, including the recurrent production burden of PECs, coronavirus genome organization, structural proteins, and the central role of the spike protein in receptor engagement, membrane fusion, and neutralizing antibody induction. Key issues are then discussed, including how spike diversity, conformational stability, epitope accessibility, glycan shielding, and antigen matching influence protective breadth; why intestinal secretory IgA, mucosal immune-cell trafficking, local memory responses, and lactogenic immunity should be prioritized as biologically relevant endpoints; and how delivery route, adjuvant selection, and platform design shape response quality. Current evidence on recombinant protein, viral-vectored, nanoparticle, virus-like particle, probiotic, plant-derived, and mRNA-based approaches is compared with attention to both promise and current evidentiary and translational limitations. The available literature suggests that future progress in PEC vaccinology is likely to depend less on platform novelty alone than on integrated vaccine designs that align antigen selection, mucosal delivery, maternal–neonatal protection, heterologous challenge, manufacturability, and field applicability. Full article

Background/Objectives: Respiratory syncytial virus (RSV) causes a significant hospitalization burden in infants. The objective of this study was to evaluate the cost-effectiveness of introducing clesrovimab, a recently approved long-acting monoclonal antibody, in all US infants born during or entering their first RSV season. Methods: A decision analytical model simulated the clinical and economic impact of clesrovimab in a yearly birth cohort, compared with three alternative interventions: nirsevimab, palivizumab, and the RSVpreF maternal vaccine. Model inputs were obtained from the published literature. Efficacy estimates for clesrovimab were derived from post hoc analyses of randomized control trial data, which were conducted to align endpoints from different studies (nirsevimab and RSVpreF). Medically attended lower respiratory infection (MALRI), quality-adjusted life years (QALYs, 3% discounting), and costs (in 2024 USD) were evaluated from a societal perspective. Both deterministic and probabilistic sensitivity analyses were performed. Results: Clesrovimab resulted in fewer (38,252) RSV-related MALRI outcomes and was cost-saving compared to nirsevimab, with significant reductions in total costs (USD 98 million saved). When compared with palivizumab, clesrovimab and nirsevimab were estimated to cost USD 38,655 and USD 79,912 per QALY, respectively. Results were sensitive to changes in intervention costs, efficacy, and QALY loss due to RSV infection. Conclusions: Clesrovimab may significantly reduce the burden of RSV among US infants in their first RSV season and may save costs compared to nirsevimab. Full article

Background/Objectives: Bordetella bronchiseptica is a Gram-negative bacterium that, either acting alone or in concert with other bacterial or viral pathogens, is a major cause of the canine infectious respiratory disease (CIRD) complex in dogs. Most currently available vaccines are given intranasally or orally and, whilst providing satisfactory reduction in disease severity, can be difficult to use especially in aggressive or anxious dogs. Whilst a small number of injectable B. bronchiseptica vaccines have been developed, little is known about their characteristics with regard to the age at first vaccination, the onset of immunity, duration of immunity, induction of antibody responses, concurrent use with the core vaccines used in most dogs, efficacy in the face of maternally derived antibodies (MDAs) or existing immunity and safety in pregnant animals. Here we describe the development of a safe and efficacious injectable B. bronchiseptica vaccine that utilises a novel process to purify fimbriae. Methods: The fimbrial antigen was formulated with a vitamin E-based oil-in-water adjuvant known to be safe in dogs (Nobivac^® Respira Bb). To evaluate dose response, thirty-nine naïve 5–6-week-old Beagle puppies were allocated to four groups and vaccinated subcutaneously with Nobivac^® Respira Bb at 69 U, 25 U, and 7 U (with a booster at two weeks). All groups were challenged with B. bronchiseptica two weeks after the booster. To evaluate the onset of immunity at 5–6 weeks of age, twenty-one naïve Beagle dogs were split into two groups: group 1 received Nobivac Respira Bb (88 U/dose) plus Nobivac DHPPi and Nobivac L4; group 2 received DHPPi and L4 only. Both groups were challenged with B. bronchiseptica two weeks after the second vaccination. Safety in pregnancy was evaluated by vaccinating pregnant dams and monitoring whelping outcomes and puppy health. Protection in puppies with maternally derived antibodies (MDAs) was studied in 28 pups (11 MDA-negative and 17 MDA-positive from vaccinated and unvaccinated dams). Pups were vaccinated at 5–6 weeks; one group remained unvaccinated to monitor MDA kinetics. All puppies were challenged with B. bronchiseptica at 19 weeks, after MDAs became undetectable. Serology was monitored throughout; daily clinical observations and nasal swabs post-challenge assessed protection and bacterial shedding. Results: Nobivac Respira Bb (MSD Animal Health), was safe for use in 5–6-week-old puppies alongside other Nobivac core canine vaccines without vaccine interference. The vaccine has an onset of immunity of two weeks and significantly reduces both the clinical signs of B. bronchiseptica-induced disease and bacterial excretion into the environment. Furthermore, the vaccine is equally efficacious in puppies with maternally derived antibodies derived from vaccinated dams and can be used safely in pregnant bitches. Conclusions: This vaccine represents a convenient, safe and efficacious alternative to vaccines delivered via the oral or intranasal routes and is a positive addition to the range of vaccines targeted at reducing disease induced by B. bronchiseptica. Full article

The endemicity of H9N2 avian influenza viruses (AIVs), particularly the Y280 lineage, poses persistent challenges to the poultry industry due to the limitations of inactivated vaccines, such as interference by maternally derived antibodies (MDAs) and incomplete suppression of viral replication. This study evaluated the immunogenicity and protective efficacy of a novel recombinant turkey herpesvirus vaccine expressing the hemagglutinin gene of H9N2/Y280 (rHVT-H9/Y280) in commercial Hy-Line Brown layers with high-MDA backgrounds. In a comparative challenge study, the rHVT-H9/Y280 vaccine induced complete protection against a homologous Y280 strain challenge at 4 weeks of age, whereas commercial inactivated vaccines failed to completely block replication, showing virus isolation rates of 16.7–25%. Long-term serological monitoring demonstrated that the rHVT-H9/Y280 vaccine elicited a robust humoral response characterized by persistent maintenance of high HI titers (>8.0 log₂) up to 39 weeks post-vaccination. These findings confirm that rHVT-H9/Y280 effectively overcomes MDA interference and provides protection by inhibition of viral replication in layer chickens, making it a promising candidate for the effective control of H9N2 AIV in endemic regions. Full article

Background: Non-typhoidal Salmonella (NTS) is a major foodborne pathogen, with poultry products, especially eggs, being the primary source of human infections. Current serovar-specific poultry vaccines effectively reduce targeted Salmonella serovars but may inadvertently promote the emergence of untargeted serovars within poultry flocks. Therefore, novel vaccine candidates providing broad cross-serovar protection are needed to improve overall effectiveness of Salmonella control programs. Objectives: This study evaluated the immunogenicity of the novel subunit vaccine candidate InvG and assessed its ability to reduce Salmonella colonization in vaccinated laying hens and their progeny through maternally derived antibodies transferred via egg yolk. Methodology: Three experiments were performed. Experiment I evaluated the immunogenicity of purified recombinant InvG by (a) measuring anti-InvG antibodies using an enzyme-linked immunosorbent assay (ELISA) and (b) completing transcriptomic profiling of immune responses in vaccinated chickens. Vaccinated chickens were subsequently challenged with Salmonella Enteritidis to assess the efficacy of anti InvG antibodies in reducing intestinal colonization of Salmonella. Experiment II involved immunizing hens with InvG, to evaluate passive transfer of antibodies via egg yolk and the protective efficacy of maternally derived antibodies against Salmonella challenge. Passive transfer was assessed by measuring IgY antibodies in hen serum, egg yolk, and progeny serum, as well as secretory IgA (sIgA) antibodies in progeny intestinal washings using ELISA. Protective efficacy was evaluated by orally challenging one-day-old chicks with three different Salmonella serovars. Experiment III assessed the persistence of anti-InvG antibodies in the serum of vaccinated hens and their transfer into eggs following two doses of InvG. Results: InvG vaccination induced robust IgY antibody responses in hens, with efficient maternal antibody transfer to progeny via egg yolk. A statistically significant reduction in Salmonella colonization was observed in both vaccinated hens and their progeny. Conclusions: These findings demonstrate that InvG represents a promising subunit vaccine candidate for Salmonella control in poultry and warrants further investigation towards development as a broadly protective commercial poultry vaccine against Salmonella. Full article

During their early life, puppies are protected against infectious agents with the presence of maternal derived antibodies (MDA). Vaccination is recommended to start as soon as the levels of MDA begin to wane to ensure that the puppy’s immune system can respond effectively to the vaccines and develop active immunity against diseases. Two studies were designed to assess the efficacy of the Canigen^TM DHPPi vaccine in puppies from 6 weeks of age. The studies comprised two parts: the efficacy assessment of the Canine Parainfluenza Virus (CPiV) vaccine component against a virulent challenge with CPiV (Experiment A) and an immunogenicity assessment of Canine Distemper Virus (CDV), Canine Adenovirus (CAV-2), and Canine Parvovirus (CPV-2) vaccine components (Experiment B). In Experiment A, twelve puppies were immunized with two injections of Canigen^TM DHPPi (at minimum titer) two weeks apart and twelve control puppies received the vaccine diluent. All animals were challenged with a virulent, heterologous CPiV strain two weeks after the second vaccination. Vaccinated puppies exhibited a significant reduction in nasal viral shedding compared to the control group. Clinical signs of respiratory disease were mild and transient in both groups. In Experiment B, six puppies were immunized with two injections of Canigen^TM DHPPi (at minimum titer) two weeks apart. A follow-up of the seroneutralizing antibodies titers against the CDV, CAV-2 and CPV-2 vaccine components was performed in order to assess the efficacy on the serological response basis. After the first vaccine injection, all the puppies seroconverted and presented seroneutralizing antibody titers reaching a protective thresholds against CDV (≥10^0.82), CAV-2 and CAV-1 (≥10^0.82), CPV-2 and CPV-2c (≥10^1.8). After the second vaccine injection, a more robust immune response was observed and the seroneutralizing antibody titers remained high until 4 weeks post vaccination for those three vaccine components. In both experiments (A and B), all vaccinated animals remained in good health, with no adverse reactions recorded during the vaccination phase. As a conclusion, the efficacy of the Canigen^TM DHPPi vaccine was demonstrated when administered in dogs from 6 weeks of age. These results fully support the interest of an early vaccination in such young puppies followed by the recommended vaccination scheme. Full article

Antimicrobial resistance (AMR) is an increasing concern in food animal production. In swine herds, viral infections often lead to secondary bacterial disease and higher antimicrobial use (AMU). This study describes how U.S. swine veterinarians view the role of viral vaccines in reducing this reliance on antimicrobials. We conducted a national survey of swine practitioners and follow-up semi-structured interviews with a subset of respondents. Across participants, porcine reproductive and respiratory syndrome (PRRS), swine influenza (SIV), and rotaviral enteritis were most often named as viral diseases in urgent need of improved vaccines. These diseases cause substantial economic losses and frequently trigger AMU in commercial herds. Veterinarians reported several recurring challenges with current vaccines, including limited cross-protection against field strains, interference from maternally derived antibodies, and short duration of protection. Despite these limitations, most respondents supported vaccination as a key tool to curb AMU and indicated they would accept higher prices for clearly improved products. These findings reveal both a clear need and specific opportunities for future vaccine development to provide broader and more reliable protection, reduce AMU, and help slow the development of AMR. Full article

Kittens are born with some maternally derived antibodies (MDA) that, together with maternal gut microbiota, bring some form of early defense against pathogens. However, this protection declines and the rapid changes and challenges the kitten typically encounters can adversely affect their health. Nutrition can modulate the immune system and gut microbiota, offering a boost to protection following weaning. This controlled, randomized, double-blinded study tests a dietary supplement containing nucleotides, oligosaccharides, vitamin E and β-carotene in 50 domestic short-haired kittens. Control kittens were fed standard, dry kitten diet whilst test kittens received the same diet with supplement for 52 weeks. Kittens received routine vaccinations and blood samples were collected throughout the study for standard hematology, serum antibodies and cytokine expression. Rectal fecal samples were analyzed for gut microbiota via 16S rRNA gene sequencing. Supplemented kittens showed significantly improved antibody response to Chlamydia vaccine at various timepoints versus controls, with no consistent effects of supplementation on responses to other vaccines. Several cytokines were significantly influenced by the supplement, which also significantly altered gut microbiota diversity. In conclusion, a dietary supplement was shown to promote immune response and gut microbiota changes in kittens and may help to support a healthy transition into adulthood. Full article

Preeclampsia (PE) is a serious gestational complication that affects the lives of the mother and the child. Women with PE showed higher levels of pro-inflammatory cytokines secreted by leukocytes compared with women with normal pregnancies. The differences are most noticeable in the percentage of CD16+ monocytes, although the mechanism underlying this increase remains unclear. The CD16 receptor is critical for antibody-dependent cellular cytotoxicity, and by binding to antibodies on the surface of target cells, it activates their death. In this study, we examined the effect of soluble placental factors on the expression of CD16 monocytes and the potential role the soluble form of human leukocyte antigen (HLA) has on CD16 monocyte expression. At the first stage of our study, we collected samples of placental villi fragments from 58 pregnant women (38 women with PE and 20 with a healthy pregnancy). Then we studied the effect of placental villus-conditioned culture medium on CD16 expression by monocytes derived from the same women. It was shown that the content of CD16+ monocytes increased significantly in women with PE within 3 h and to a lesser extent in women with a healthy pregnancy (p = 0.009). Also, the addition of the recombinant histocompatibility HLA-B to the placental villus-conditioned culture medium blocks the induction of CD16 expression on monocytes. At the second stage of our study, we typed HLA class I and class II alleles in the umbilical cord blood samples and the venous blood samples taken from 38 women with PE and 40 women with a normal pregnancy. It was found that certain HLA class II alleles predominate in women with preeclampsia. The DRB1*01:01:01G allele showed the greatest difference (p < 0.001). Analyzing five alleles simultaneously makes it possible to predict the PE with AUC = 0.76. Evaluation of unique children’s alleles also showed that class II alleles have greater differences among them than class I alleles. The DQB1*06:03:01G allele had the greatest differences with p = 0.03 (the number was higher in the control group). Performing an analysis of four alleles of children simultaneously allowed us to predict PE with an AUC of 0.64. This work suggests that the activation of CD16+ monocyte expression occurs due to the interaction of soluble placental antigens with monocytes. The most likely way to activate CD16 expression on monocytes is by HLA class II (both maternal and fetal) interaction with CD4 receptors on the surface of monocytes, whereas HLA class I is capable of blocking this process. Evaluation of maternal HLA alleles may be a significant marker for predicting PE. Full article

Background/Objectives: Maternally derived antibody (MDA) levels of porcine circovirus 2 (PCV2) may eventually interfere with humoral response and vaccination efficacy. This study aimed to evaluate the efficacy of a ready-to-use PCV2d and Mycoplasma hyopneumoniae combined vaccine in piglets with different PCV2 MDA levels at vaccination in an experimental inoculation with a heterologous viral genotype. Methods: Forty-eight piglets were allocated into vaccinated (V) and non-vaccinated (NV) groups with high (H) and low (L) PCV2 MDA subgroups (H-V, H-NV, L-V, L-NV). At 3 weeks of age, the piglets received either one dose of vaccine or placebo. Five weeks later, all animals were intranasally challenged with a PCV2b inoculum. Body weight was registered at different time points. Blood samples, peripheral blood mononuclear cells and tracheobronchial lymph nodes (TBLN) were collected and used to assess viraemia, viral load, humoral and cellular responses and histological lesions. Results: The V group showed higher PCV2 antibody levels from challenge onwards, along with a lower percentage of viraemic pigs and reduced viral load in serum at 2 and 3 weeks post-challenge (wpc) and in TBLN tissues compared to the NV group. The H-V group had the highest antibody levels post-challenge, showed no detectable viraemia and had a lower overall amount of virus in tissues. The NV group (especially H-NV) exhibited increased levels of IFN-γ, IFN-α and TNF-α post-challenge. Conclusions: The tested vaccine elicited humoral and cellular immune responses and reduced viral presence in serum and tissues, demonstrating efficacy in a PCV2 subclinical infection model despite high MDA levels at the time of vaccination. Understanding both humoral and cellular immune responses according to different MDA levels can help design more effective vaccination strategies against PCV2. Full article

Antibody titer testing can be useful in controlling successful puppy immunization and can reduce unnecessary vaccinations in adult dogs. We evaluated three commercially available point-of-care tests (POCTs) for detecting antibodies against canine parvovirus (CPV-2), canine distemper virus (CDV) and canine adenovirus (CAV-1 and/or -2), comparing them to the reference virus neutralization (VN) assay. Sera from 200 client-owned dogs (13 healthy, 63 chronically diseased, 124 acute) and 60 specific pathogen-free (SPF) dogs, including 20 sera with maternally derived antibodies (MDA), were tested. All three POCTs demonstrated high sensitivity (79.0–100%) and specificity (97.8–100%) for CPV-2. In contrast, specificity for CDV and CAV was lower with POCT-1 (43.5% and 55.3%) and POCT-2 (42.4% and 79.2%), despite high sensitivity (CDV in both POCTs 98.7%; CAV POCT-1: 99.4%, POCT-2: 90.8%). POCT-3, by comparison, showed high specificity (CDV: 94.1%; CAV: 84.4%) but very low sensitivity (CDV: 17.4%; CAV: 33.1%). Only POCT-1 for CPV-2 detected MDA reliably, whereas the other two POCTs, and POCT-1 for CDV and CAV, did not. When compared to VN, the agreement in vaccination recommendations was 82% for POCT-1 and POCT-2, and 62% for POCT-3. In conclusion, all three POCTs reliably detected antibodies against CPV-2, including MDA with POCT-1. However, the lower specificity for CDV and CAV antibody detection in POCT-1 and POCT-2 raises concerns about misclassifying unprotected dogs as immune, while false-negatives with POCT-3 could lead to unnecessary vaccinations. Further optimization of all three POCTs for CDV and CAV is recommended. Full article

Background/Objectives: Typically, studies aiming to assess the ability of canine parvovirus (CPV) vaccines to immunise puppies with maternally derived antibody (MDA) are undertaken using group-housed puppies. Since live attenuated vaccine virus is invariably shed in the faeces, this can result in repeated oral re-exposure and puppies which failed to respond to the initial vaccination may respond instead to shed vaccine virus in the environment, thus artificially enhancing the efficacy of the vaccine. This problem can be avoided by adopting a pair-housed study design where one vaccinated pup is housed with one unvaccinated sentinel. Using this design, we examine the capability of four commercially available canine parvovirus vaccines to immunise MDA-positive pups. Methods: Thirty-four 6-week-old puppies born to vaccinated dams were divided into four vaccine groups with similar MDA ranges. Within each group puppies were paired based on matching MDA titres, and each pair was housed in separate biocontainment accommodation. In each pair, the pup with the highest MDA was vaccinated and the other left as an unvaccinated sentinel. All vaccinates were given a single dose of one of the vaccines. Vaccinates and sentinels were then bled every 2–4 days and CPV antibody was measured. Daily rectal swabs were also collected from all pups to identify any shed vaccinal CPV. Results: All the pups vaccinated with Nobivac DP PLUS seroconverted, with significantly higher antibody titres compared to the pups in other vaccine groups, all shed vaccine virus, and all bar one of the sentinel pups seroconverted. In the other groups, only vaccinated pups with lower levels of MDA seroconverted and shed vaccine virus but none of the sentinel pups seroconverted. Conclusions: Different canine parvovirus vaccines differ in their ability to replicate in and immunise puppies with MDA, the levels of which may vary widely between individuals. The shedding of vaccinal CPV is an important consideration when designing studies to demonstrate efficacy in MDA-positive puppies. Full article