Humoral immune response profile of a cattle herd vaccinated with 5- and 10-times Bakirköy strain sheep pox vaccine under field conditions

Vaccination is the most effective control measure for Lumpy Skin Disease (LSD). The Bakırköy strain-derived sheep pox vaccine (SPPV) has been used against LSD in Türkiye since 2013. In this study, a cattle herd was vaccinated with SPPV and 35 cattle, of which 9 and 26 received 10 and 5 sheep doses, respectively, were followed for 200 days for humoral immune responses. Additionally, maternal antibodies in colostrum-fed calves were investigated. The humoral immune responses of naive and previously vaccinated cattle were compared to determine the effects of annual re-vaccination. Furthermore, the compatibility of the VNT and ELISA tests was analyzed. According to the results, on day 30 post-vaccination, 19 and 13 out of 35 cattle were positive for VNT and ELISA, respectively. The number of seropositive cattle was higher in the group that had been vaccinated in previous years than in naive cattle. No significant differences were observed in the number of positive cattle between the groups vaccinated with the 5- and 10- doses. In colostrum-fed calves grouped according to age, the seropositivity rate was 87 % (41/47) in the one-week-old group, while this rate was only 18 % (3/16) in the 3-month-old group. It was determined that vaccination at different stages in the last four months of pregnancy did not cause any difference in the number of seropositive calves in one-week-old calves fed with colostrum. The concordance between VNT and ELISA tests was lower in 5-dose vaccinated group than 10-dose vaccinated and colostrum-fed calves groups. This study provides insights into the effect of the vaccination strategy followed by Türkiye during its combat of LSD and revealed that annual repeated vaccination using heterologous vaccine has significant positive effects on humoral immun response at the herd level.

Protective efficacy of a recombinant enterotoxin antigen in a maternal immunization model and the inhibition of specific maternal antibodies to neonatal oral vaccination

ETEC (enterotoxigenic Escherichia coli) infection is the leading cause of profuse watery diarrhea in mammals, especially among pre-weaning and post-weaning piglets in swine industry. Maternal immunization is a current rational strategy for providing protection to susceptive piglets and reducing the incidence of ETEC-associated diarrhea. Here we evaluated the protective efficiency of a recombinant antigen (MBP-SLS) fused by major enterotoxin subunits (STa-LTB-STb) via a maternal immunization model, and the impacts of maternal antibodies to neonatal oral vaccination were also investigated in the neonates. The high titers of specific IgG and sIgA in pups shown that the maternal antibodies could be transferred passively. Furthermore, the increases of IL-6 and IL-10 cytokines in breast milk and pup serum indicated that immunization on mother could effectively boost the immune system of neonates. Newborn rats from immunized mothers showed a 70% survival rate after ETEC infection. However, the mucosal immune responses of neonates were inhibited by the high level of maternal specific antibodies. Among the oral-vaccinated neonates, born from mock-immunized rats reached the highest survival after ETEC challenge. Collectively, the fusion MBP-SLS antigen could effectively induce strong immune responses in rats during pregnancy and the pups could receive passive protection through specific antibodies transferred via milk and placenta. However, the specific maternal antibodies exhibited an inhibition effect on the mucosal immune responses in offspring.

Waning of maternal antibody against measles virus in Shufu, China

BACKGROUND

As measles vaccination coverage has increased, measles infection has shifted to the population of infants. We conducted a follow-up seroepidemiological study among mothers and their infants to evaluate measles seroprevalence and the persistence of maternal measles antibody in Shufu, Kashgar from 2018 to 2020.

METHODS

Maternal venous blood and cord blood was obtained among mothers and their infants at 0, 3, 5, 8, 9, and 12 months of age. An enzyme-linked immunosorbent assay was used for quantitative measurement of measles antibodies. We analyzed the correlation between maternal and neonatal measles antibodies, and antibodies persistence after infants were born.

RESULTS

The overall neonatal maternal ratio was 2.38 (95%CI: 2.05-2.71). The measles antibodies for mothers and newborns were 438.93 IU/mL (95%CI: 409.47-470.51 IU/mL) and 440.10 IU/mL (95%CI: 410.82-471.48 IU/mL), respectively. Neonatal measles antibodies were dropping after birth and then beginning to increase starting at 8 months of age.

CONCLUSIONS

Infant measles antibody levels progressively declined after birth regardless of maternal measles antibody levels. Efforts should be carried out to eliminate measles.

The transfer of maternal antibodies and dynamics of maternal and natural infection-induced antibodies against coxsackievirus A16 in Chinese children 0-13 years of age: a longitudinal cohort study

BACKGROUND

A major hand-foot-and-mouth disease (HFMD) pathogen, coxsackievirus A16 (CVA16), has predominated in several of the last 10 years and caused the largest number of HFMD outbreaks between 2011 and 2018 in China. We evaluated the efficacy of maternal anti-CVA16 antibody transfer via the placenta and explored the dynamics of maternal and natural infection-induced neutralizing antibodies in children.

METHODS

Two population-based longitudinal cohorts in southern China were studied during 2013-2018. Participants were enrolled in autumn 2013, including 2475 children aged 1-9 years old and 1066 mother-neonate pairs, and followed for 3 years. Blood/cord samples were collected for CVA16-neutralizing antibody detection. The maternal antibody transfer efficacy, age-specific seroprevalence, geometric mean titre (GMT) and immune response kinetics were estimated.

RESULTS

The average maternal antibody transfer ratio was 0.88 (95% CI 0.80-0.96). Transferred maternal antibody levels declined rapidly (half-life: 2.0 months, 95% CI 1.9-2.2 months). The GMT decayed below the positive threshold (8) by 1.5 months of age. Due to natural infections, it increased above 8 after 1.4 years and reached 32 by 5 years of age, thereafter dropping slightly. Although the average duration of maternal antibody-mediated protection was < 3 months, the duration extended to 6 months on average for mothers with titres ≥ 64.

CONCLUSIONS

Anti-CVA16 maternal antibodies are efficiently transferred to neonates, but their levels decline quickly. Children aged 0-5 years are the main susceptible population and should be protected by CVA16 vaccination, with the optimal vaccination time between 1.5 months and 1 year of age.

Serological survey for maternal antibodies to Borreliella burgdorferi and Anaplasma phagocytophilum in dogs from endemic and non-endemic regions of the United States

In North America, the tick-borne pathogens Borreliella burgdorferi (Lyme disease; LD) and Anaplasma phagocytophilum (anaplasmosis) are a significant health threat to dogs. Little is known regarding the seroprevalence of maternal antibodies (Abs) to these pathogens in young dogs. The analysis of maternal antibody (Ab) profiles is important as it could bear on the interpretation of currently available diagnostic assays and the potential for vaccine interference in pups. In this pilot study, sera from 32 client-owned dogs (6-24 weeks of age; 3 serum samples per dog) from four veterinary hospitals in the United States were screened for IgG against B. burgdorferi and A. phagocytophilum using whole cell lysate immunoblots and recombinant protein-based ELISAs. As a control, the sera were also screened for Abs to canine parvovirus and canine distemper virus using a commercially available colorimetric assay. Maternally derived Abs against B. burgdorferi including the diagnostic antigen VlsE were detected in 2 of the 32 dogs, accounting for 12.5 % of dogs from LD endemic regions, and as expected, the Ab levels declined over time. Differentiating between maternal Ab and infection-induced Ab is of importance in interpreting serological tests for tick-borne diseases in young dogs and in making decisions regarding treatment and timing of vaccination.

Effect of early two-dose measles vaccination on childhood mortality and modification by maternal measles antibody in Guinea-Bissau, West Africa: A single-centre open-label randomised controlled trial

BACKGROUND

Early 2-dose measles vaccine (MV) at 4 and 9 months of age vs. the WHO strategy of MV at 9 months of age reduced all-cause child mortality in a previous trial. We aimed to test two hypotheses: 1) a 2-dose strategy reduces child mortality between 4 and 60 months of age by 30%; 2) receiving early MV at 4 months in the presence versus absence of maternal measles antibodies (MatAb) reduces child mortality by 35%.

METHODS

Single-centre open-label community-based randomised controlled trial in Guinea-Bissau, with 2:1 block-randomisation by sex to a 2-dose (4 + 9 months) vs. 1-dose (9 months) MV strategy. Healthy children were eligible 4 weeks after the 3rd diphtheria-tetanus-pertussis-containing vaccine. Before randomisation a blood sample was collected to determine MatAb level. The primary outcome was all-cause mortality. Hazard ratios (HR) were derived from Cox regression in the per protocol population. We tested for interactions with national campaigns with oral polio vaccine (C-OPV). Trial registration: NCT01486355.

FINDINGS

Between August 2011-April 17th 2015, 6,636 children were enroled, 6,598[n_2-dose=4,397; n_1-dose=2,201] were included in the analysis of the primary outcome, The HR(2-dose/1-dose) between 4 and 60 months was 1.38 (95%CI: 0.92-2.06) [deaths: n_2-dose=90; n_1-dose=33]. Before the 9-month MV and the HR(1-dose/no dose) was 0.94 (0.45-1.96) [deaths: n_2-dose=21; n_1-dose=11]. The HR(2-dose/1-dose) was 0.81 (0.29-2.22) for children, who received no C-OPV [deaths/children: n_2-dose=10/2,801; n_1-dose=6/1,365], and 4.73 (1.44-15.6) for children, who received C-OPV before and after enrolment (p for interaction=0.027) [deaths/children: n_2-dose=27/1,602; n_1-dose=3/837]. In the 2-dose group receiving early MV at 4 months, mortality was 50% (20-68%) lower for those vaccinated in the presence of MatAb vs. the absence of MatAb [deaths/children: n_MatAb=51/3,132; n_noMatAb=31/1,028].

INTERPRETATION

The main result contrasts with previous findings but may, though based on a small number of events, be explained by frequent OPV campaigns that reduced the mortality rate, but apparently interacted negatively with early MV. The beneficial non-specific effects of MV in the presence of MatAb should be investigated further.

FUNDING

ERC, Danish National Research Foundation, the Danish Council for Development Research, Ministry of Foreign Affairs, Novo Nordisk Foundation, European Union and the Lundbeck Foundation.

Maternal transfer of antibodies specific for avian influenza viruses in captive whooper swans (Cygnus cygnus)

The transfer of maternal antibodies to offspring can effectively protect against avian influenza virus (AIV) infection during early life in chickens and can prevent AIV spread by decreasing the overall percentage of the avian population susceptible to this pathogen. Herein, we evaluated maternal antibody transfer dynamics in whooper swans (Cygnus cygnus), which represent an important AIV host species. In total, 57 eggs from 19 nests were collected to study the relationship between egg yolk AIV-specific antibody concentrations and factors including egg size, laying order, maternal serum AIV antibody titer, and maternal body condition. Overall, we found that AIV-specific antibodies were present in the serum of 63.2 % of surveyed female swans and were transferred to 50.8 % of analyzed eggs. We found maternal AIV-specific antibody concentration and body weight to be positively correlated with egg yolk AIV antibody concentration, whereas egg laying order was negatively correlated with yolk antibody titer. Overall, these findings maternal transfer of AIV-specific antibodies may function as a key mechanism governing the dynamics of AIV infection in swan populations.

Combined use of two separate but protective vaccine antigens provides protection against Taenia ovis infection in lambs in the presence of protective maternal antibody

Three recombinant Taenia ovis antigens (To45, To16, To18) each induce protective immunity in lambs or ewes against infection with T. ovis metacestodes. The degree and duration of immunity were assessed in lambs born from vaccinated ewes. Treatment group sizes varied, typically not fewer than 5 animals per group. Ewes were immunised with one T. ovis recombinant protein prior to lambing and the degree and duration of passive immunity in their lambs was assessed by challenge infection up to 18 weeks. Lambs were fully protected up to 6 weeks of age but immunity waned from 6 to 12 weeks and there was no protection when lambs were challenged at 15 weeks. Immunisation of lambs with the homologous recombinant antigen was not effective when vaccinations were given when maternal antibody was high. Lambs were effectively immunised in the presence of passively protective antibody when vaccinated with an antigen that was different to that given to ewes. Vaccination of lambs with a combination of two proteins, To16 and To18, was more effective than giving these single antigens and gave a significant reduction of cyst numbers when lambs were challenged 12 months after immunisation. These results indicate that the use of combinations of T. ovis recombinant antigens could enable complete protection of lambs against infection, if a delivery system becomes available that will maintain antibody at protective levels for 12 months. Alternatively, a third injection given at 6 months may promote the anamnestic response to give long lasting protection.

Protection against herpes simplex virus type 2 infection in a neonatal murine model using a trivalent nucleoside-modified mRNA in lipid nanoparticle vaccine

Neonatal herpes is a dreaded complication of genital herpes infection in pregnancy. We recently compared two vaccine platforms for preventing genital herpes in female mice and guinea pigs and determined that HSV-2 glycoproteins C, D and E expressed using nucleoside-modified mRNA in lipid nanoparticles provided better protection than the same antigens produced as baculovirus proteins and administered with CpG and alum. Here we evaluated mRNA and protein immunization for protection against neonatal herpes. Female mice were immunized prior to mating and newborns were infected intranasally with HSV-2. IgG binding and neutralizing antibody levels in mothers and newborns were comparable using the mRNA or protein vaccines. Both vaccines protected first and second litter newborns against disseminated infection based on virus titers in multiple organs. We conclude that both vaccines are efficacious at preventing neonatal herpes, which leaves the mRNA vaccine as our preferred candidate based on better protection against genital herpes.

Three non-classical mechanisms for anemic disease of the fetus and newborn, based on maternal anti-Kell, anti-Ge3, anti-M, and anti-Jra cases

Maternal alloantibody-mediated hemolytic disease of the fetus and newborn (HDFN) ranges from no or mild symptoms to severe hydrops and intrauterine fetal demise. Hemolytic anti-D-mediated HDFN proceeds via a long-known mechanism, to which three other pathways to fetal/neonatal anemia may be added: (0) Fetal erythrocyte destruction can proceed by extravascular phagocytosis. (1) An apoptotic pathway has been described for anti-Kell, and anti-Ge3. (2) Erythropoietic suppression may arise from altered or deformed erythroblast architecture in anti-M-mediated disease. (3) Clonal escape from erythropoietic suppression is hypothesized to arise from maternal anti-Jr^a immune pressure, albeit this requires further elucidation. Alloantibody-mediated anemic disease of the fetus and newborn (ADFN) is a designation we favor for cases when hemolysis or hyperbilirubinemia are not the dominant features, such as those provoked by anti-Kell, anti-Ge3, anti-M, and anti-Jr^a.

The effect of maternal poliovirus antibodies on the immune responses of infants to poliovirus vaccines

Background

Maternal poliovirus antibodies could provide passive immunity to the newborns from poliovirus infection during their first few months of life, but they may impair the immune responses of infants to the poliovirus vaccine as well. In our study, we pooled the data from three clinical trials of the inactivated poliovirus vaccine (IPV) based on Sabin strains to investigate the effect of maternal poliovirus antibodies on the immune responses of infants to poliovirus vaccines.

Methods

There were five groups in the pooled analysis, including low-dose Sabin IPV, medium-dose Sabin IPV, high-dose Sabin IPV, control Sabin IPV, and control Salk IPV groups. We reclassified the infants in different groups according to their maternal poliovirus antibodies by two methods, the first one included maternal antibody negative (< 1:8) and maternal antibody positive (≥1:8), and the second one included maternal antibody titer < 1:8, 1:8 ~ < 1:32 and ≥ 1:32. Then, we compared the geometric mean titers (GMTs), geometric mean antibody fold increases (GMIs) and seroconversion rates of poliovirus type-specific neutralizing antibodies after vaccination among participants with different maternal poliovirus antibody levels.

Results

The GMTs and GMIs of three types of poliovirus antibodies after vaccination in maternal antibody negative participants were significantly higher than those in maternal antibody positive participants. The seroconversion rates of type II and type III poliovirus antibodies in maternal antibody positive participants were significantly lower than those in maternal antibody negative participants. Among participants with maternal antibody titer < 1:8, 1:8 ~ < 1:32 and ≥ 1:32, the GMTs and GMIs of three types of poliovirus antibodies after vaccination showed a tendency to decline with the increasing of maternal antibody levels. The seroconversion rates of three types of poliovirus antibodies in participants with maternal antibody titer ≥1:32 were significantly lower than those in participants with maternal antibody titer < 1:8 and 1:8 ~ < 1:32.

Conclusions

Maternal poliovirus antibodies interfered with the immune responses of infants to poliovirus vaccines, and a high level of maternal antibodies exhibited a greater dampening effect.

Trial registration

ClinicalTrials.govNCT04264598 February 11, 2020; ClinicalTrials.govNCT04264546 February 11, 2020; ClinicalTrials.govNCT03902054 April 3, 2019. Retrospectively registered.

Antibody profiling of a Borreliella burgdorferi (Lyme disease) C6 antibody positive, symptomatic Rottweiler and her pups

Lyme disease (LD) is a tick-transmitted disease caused by Borreliella burgdorferi (Bb). Temporal studies of maternal antibody (Ab) profiles in Bb infected pregnant dogs and their pups have not been conducted. In this study, Ab profiles of a client-owned Bb C6 Ab positive Rottweiler and her nine pups were assessed. The dam presented with lameness 12 days prior to parturition and was C6 Ab positive with a Quant C6 Ab concentration of 237U/mL. Treatment with amoxicillin was initiated and 11 days later nine pups were delivered. Screening of the sera from the dam and pups against Bb cell lysates and a panel of antigens revealed similar immunoreactivity profiles. While antigen-specific IgG and IgM reactivity persisted in the dam for at least 7 months, a rapid decline in IgG specific for BBA36, BBK53, BB0238, BBA73 and outer surface protein (Osp) E in the pups occurred between days 29 and 52 post-parturition. In contrast, Ab specific for DbpA and the diagnostic antigens VlsE (C6) and OspF, remained elevated in the pups. Sera from the dam displayed potent complement-dependent bactericidal activity against Bb. Sera from the pups was also bactericidal but primarily through a complement-independent mechanism. Lastly, single dose vaccination of the dam at day 51 post-parturition with a LD subunit vaccine consisting of OspA and an OspC chimeritope triggered a broad anti-OspC Ab response indicative of an anamnestic response. Although this study focused on a single case, these findings add to our knowledge of maternal Ab profiles and will aid the interpretation of serological assays in pups delivered by a Bb C6 Ab positive dog.

Protection against bovine respiratory syncytial virus in calves vaccinated with adjuvanted modified live vaccine administered in the face of maternal antibody

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 purpose of this study was to evaluate the efficacy of an adjuvanted modified live virus (MLV) vaccine in the presence of well-defined maternal passive immunity. Calves were vaccinated at approximately 1 month of age and challenged ~90 days later when BRSV systemic antibodies were ≤1:4. Body temperature was lower at 6 and 7 days post challenge and other clinical signs were also lower in the vaccinates. Nasal viral shed was 3-4 times lower in the vaccinated animals as measured by virus isolation and polymerase chain reaction (PCR) and peaked 5 days post challenge compared to the controls (who peaked at days 6 and 7). On day 8 following challenge, animals were necropsied, and lung lobes were scored and tested for virus by PCR and indirect fluorescent assay (IFA). There was a 25-fold reduction in PCR virus detection in vaccinates and two of the vaccinated calves' lungs were PCR negative. Only 29.4% of vaccinated calves were BRSV positive on IFA testing at necropsy, while 87.5% of control calves were BRSV positive. Vaccinated calves developed a mucosal BRSV IgA response with over 50% of the vaccinated calves having IgA prior to challenge and all vaccinated calves were positive following challenge. Additionally, vaccination stimulated the production of Interferon gamma (IFN-γ) in mononuclear cells to prime the immune system. This study established that an adjuvanted MLV vaccine could provide protection against BRSV as measured by clinical, virological, and pathological parameters while also activating both mucosal and systemic immunity.

Impact of maternally derived antibodies to Plasmodium falciparum Schizont Egress Antigen-1 on the endogenous production of anti-PfSEA-1 in offspring

Background

We evaluated whether maternally-derived antibodies to a malarial vaccine candidate, Plasmodium falciparum Schizont Egress Antigen-1 (PfSEA-1), in cord blood interfered with the development of infant anti-PfSEA-1 antibodies in response to natural exposure.

Methods

We followed 630 Tanzanian infants who were measured their antibodies against PfSEA-1 (aa 810-1023; PfSEA-1A) at birth and 6, 12, 18, and 24 months of age, and examined the changes in anti-PfSEA-1A antibody levels in response to parasitemia, and evaluated whether maternally-derived anti-PfSEA-1A antibodies in cord blood modified infant anti-PfSEA-1A immune responses.

Results

Infants who experienced parasitemia during the first 6 months of life had significantly higher anti-PfSEA-1A antibodies at 6 and 12 months of age compared to uninfected infants. Maternally-derived anti-PfSEA-1A antibodies in cord blood significantly modified this effect during the first 6 months. During this period, infant anti-PfSEA-1A antibody levels were significantly associated with their P. falciparum exposure when they were born with low, but not higher, maternally-derived anti-PfSEA-1A antibody levels in cord blood. Nevertheless, during the first 6 months of life, maternally-derived anti-PfSEA-1A antibodies in cord blood did not abrogate the parasitemia driven development of infant anti-PfSEA-1A: parasitemia were significantly correlated with anti-PfSEA-1A antibody levels at 6 months of age in the infants born with low maternally-derived anti-PfSEA-1A antibody levels in cord blood and borderline significantly correlated in those infants born with middle and high levels.

Conclusions

Maternal vaccination with PfSEA-1A is unlikely to interfere with the development of naturally acquired anti-PfSEA-1A immune responses following exposure during infancy.

Effect of maternal antibody on the infant immune response to inactivated poliovirus vaccines made from Sabin strains

This study aimed to evaluate the effect of maternally derived antibody on the immunogenicity of Sabin IPV. A total of 600 infants were randomized to receive one of the five different vaccines: the high- (group A), medium- (group B) or low-dose (group C) of investigational Sabin IPV, the control Salk IPV (group D) or the control Sabin IPV (group E), at 2, 3 and 4 months of age. The post-vaccination GMTs, GMIs and seroconversion rates of poliovirus type-specific neutralizing antibody were analyzed for different maternal antibody levels. The correlations between maternal antibody levels and post-vaccination antibody responses were also modeled by linear regressions. The post-vaccination GMTs were significantly lower among infants with high maternal antibody titers for poliovirus type 1 or 2 mainly in the groups B, C, D and E. The GMIs and seroconversion rates decreased significantly with the increase of maternal antibody levels in all the five groups. In the groups A, B and C, maternal antibody levels were negatively associated with the post-vaccination antibody titers (for poliovirus type 1 and 2) and the fold increases of post-vaccination antibody (for all the 3 poliovirus types). With the reduce of potency of the investigational Sabin IPVs, the linear regression coefficients increased accordingly in the groups A, B and C. In conclusion, high levels of maternal poliovirus antibody could attenuate the immune responses to the Sabin IPVs. Altering the potency of the investigational Sabin IPVs could alter the associations between maternal antibody levels and the serologic responses of infants.

Characterization of an inactivated whole-virus bivalent vaccine that induces balanced protective immunity against coxsackievirus A6 and A10 in mice

Coxsackievirus A6 (CVA6) and CVA10 are two of the major pathogens associated with hand, foot and mouth disease (HFMD) in children. The majority of CVA6 and CVA10 infections result in mild, self-limiting episodes (fever and herpangina) in pediatric populations; however, in some cases, can proceed to severe neurological disease and death. Efforts to mitigate viral transmission to decrease the morbidity and mortality associated with infection would be greatly strengthened by the availability of an efficacious CVA6 and CVA10 bivalent vaccine. Here we report the immunogenicity and protective efficacy of a bivalent combination vaccine comprised of formaldehyde-inactivated, whole-virus CVA6 and CVA10. We demonstrate that subcutaneous delivery of the bivalent vaccine can induce antigen-specific systemic immune responses, particularly the induction of polyfunctional T cells, which elicit active immunization to achieve a protection rate of >80% in the infected neonatal mice. Furthermore, passive transfer of the antisera from vaccinated mice potently protected recipient mice against CVA6 and CVA10 challenge. Importantly, the bivalent vaccine could induce high levels of IgG and neutralizing antibodies in adult female mice and the maternal antibody transmitted to the recipient mice played an important role in controlling homotypic and heterotypic CVA6 and CVA10 infections and viral replication in vivo. Collectively, these findings indicate that there is no immunological interference between the two antigens with respect to their ability to induce virus-specific immune responses, and thus provides proof-of-concept for further development of multivalent vaccines for broad protection against HFMD.

Protection induced by a gp90 protein-based vaccine derived from a Reticuloendotheliosis virus strain isolated from a contaminated IBD vaccine

Background

Reticuloendotheliosis is an immunosuppressive disease caused by avian reticuloendotheliosis virus (REV). It is commonly found in poultry farms and has caused a notable economic loss worldwide. Despite this, there is currently no effective vaccine available to protect against REV infection.

Method

In this study, gp90 protein derived from an REV isolated from a contaminated vaccine was co-administered with cytosine-phosphate-guanine oligodeoxynucleotide (CpG-ODN) adjuvant to hens to determine if it protects their chicks against REV infection. To synthesize the gp90 protein, the gp90 gene was amplified using polymerase chain reaction, expressed in Escherichia coli, and purified. The resulting recombinant protein was injected intramuscularly into breeder hens along with CpG-ODN adjuvant and then serum antibody levels were regularly evaluated. After the fertilized eggs from these vaccinated hens had hatched, the resulting chicks were challenged with a 10^2.7 50% tissue culture infectious dose (TCID₅₀) of REV at 1 day old and the REV antibody levels in these hatched chickens were evaluated before and after the challenge. Viremia and growth rate were measured weekly and statistically analyzed.

Results

The results suggest that the gp90 recombinant protein was successfully prepared and, when used with CpG-ODN adjuvant to immunize breeder hens, induced serological antibody production against REV in both hens and their hatched chicks. In addition, the maternal antibodies induced by the gp90 protein vaccine effectively protected majority of the chicks from REV infection.

Conclusions

Overall, we found the gp90 protein obtained in this study may be a potential vaccine candidate that had good immunogenicity and could be an auxiliary measure to accelerate the eradication of REV.

Prevalence and decay of maternal pneumococcal and meningococcal antibodies: A meta-analysis of type-specific decay rates

Background

At the time of an infant’s initial vaccination at age ∼2 to 3 months, some infants already have maternal antibodies against vaccine antigens and these can suppress the immune response to vaccination. Modelling the effects of maternal antibody and the timing of infant doses on the antibody response to vaccination, requires estimates of the rate of maternal antibody decay. Decay rates are not well characterised in the medical literature. We investigated variation in the prevalence of maternal anti-capsular pneumococcal and meningococcal antibodies in infants in 14 countries, and estimated type-specific half-lives.

Methods

Individual participant serological data were obtained from clinical trials. Half-lives were estimated from antibody concentrations in infants who did not receive meningococcal or pneumococcal vaccines.

Results

The seroprevalence of maternal pneumococcal antibodies was highest for serotypes 14, and 19F (92% and 80% respectively) and lowest for serotypes 4 and 1 (30% and 34% respectively). Half-life estimates ranged from 38.7 days (95% CI 36.6–41.0) for serotype 6B, to 48.3 days (95% CI 46.7–50.2) for serotype 5. The overall half-life was 42.6 days (95% CI 41.5–43.7). Seroprevalence was highest in Mali, Nigeria, India, and the Philippines, (all >65%) and lowest in the Czech Republic and Finland (both <45%).

In studies of meningococcal vaccines, seroprevalence was 13% for group C (half-life 39.8 days, 95% CI 33.4–49.4) and 43% for group A (half-life 43.1 days 95% CI 39.8–47.2).

Conclusion

Substantial proportions of infants in many countries have antibodies to vaccine serotypes of pneumococcus, however fewer infants have maternally acquired antibodies to groups A and C meningococcus.

Passively-acquired antibodies to capsular polysaccharides decay with a half-life of approximately 6 weeks. These estimates are useful for modelling the impact of proposed vaccination programmes, and consideration of schedules with a delayed start.

Newcastle disease virus vectored infectious laryngotracheitis vaccines protect commercial broiler chickens in the presence of maternally derived antibodies

Newcastle disease virus (NDV) recombinants expressing the infectious laryngotracheitis virus (ILTV) glycoproteins B and D have previously been demonstrated to confer complete clinical protection against virulent ILTV and NDV challenges in naive chickens. We extended this study to assess whether maternally derived antibody (MDA) against NDV and ILTV would interfere with protection in vaccinated broiler chickens. Chickens with a mean NDV MDA hemagglutination inhibition (HI) titer of 6.4 (log₂) and detectable ILTV neutralization (VN) antibodies at hatch were vaccinated with rLS/ILTV-gB or rLS/ILTV-gD at 1 or 10day of age (DOA) or on both days. Groups of birds vaccinated with the commercial ILT vaccines (FP-LT and CEO) or sham inoculated were also included in this study. All vaccinated birds were challenged with virulent ILTV strain at 21 DOA. By that time, NDV HI titers declined to 2.6 (log₂) in unvaccinated birds, whereas the HI titers in NDV vectored vaccine groups increased to 3.5-6.3 (log₂). At standard dosages, both vaccine candidates conferred significant clinical protection; however, the protection elicited by the rLS/ILTV-gD was superior to that of rLS/ILTV-gB. Recombinant rLS/ILTV-gD reduced ILTV shedding from tracheal and ocular tissues by approximately 3 log₁₀ TCID₅₀. Notably, there was no improvement in protection after booster vaccination at 10 DOA. Overall results indicate that the presence of maternal antibodies to NDV and ILTV did not significantly interfere with the ability of the NDV LaSota strain-vectored ILTV gB and gD vaccine candidates to elicit protective immunity against infectious laryngotracheitis.

Practical aspects in the use of passive immunization as an alternative to attenuated viral vaccines

Passive immunization as a method to protect birds has been tested for many years and shown to be effective. Its advantages over active vaccination include no use of partially virulent viruses, overcoming the gap in the level of protection at young age due to interference of maternal antibodies to raise self-immune response following active vaccination and the possible immunosuppressive effect of attenuated vaccine viruses. However, a major obstacle to its implementation is its relatively high cost which is dependent, among other things, mainly on two factors: the efficacy of antibody production, and the use of specific pathogen-free (SPF) birds for antibody production to avoid the possible transfer of pathogens from commercial layers. In this study we show efficient production of immunoglobulin Y (IgY) against four different pathogens simultaneously in the same egg, and treatment of the extracted IgY with formalin to negate the need for SPF birds. Formalin, a common registered sterilization compound in vaccine production, was shown not to interfere with the Fab specific antigen binding or Fc-complement activation of the antibody. Following injection of 1-day-old broilers with antibodies against infectious bursal disease virus, protective antibody levels were acquired for the entire period of sensitivity to this pathogen (35 days). Passive vaccination with formalin-sterilized IgY against multiple antigens extracted from one commercial egg may be a cost-effective and advantageous complementary or alternative to attenuated vaccines in poultry.

The transfer and decay of maternal antibody against Shigella sonnei in a longitudinal cohort of Vietnamese infants

•

Shigella sonnei is an emergent and highly drug resistant diarrheal pathogen.

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The half-life of maternal S. sonnei IgG in infants is 43 days.

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Maternal titer, antibody transfer ratio and gestational age influence birth titer.

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Incidence of seroconversion in infants in southern Vietnam is 4/100 infant years.

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Children should be vaccinated after 5 months of age if a candidate is licensed.

Background

Shigella sonnei is an emergent and major diarrheal pathogen for which there is currently no vaccine. We aimed to quantify duration of maternal antibody against S. sonnei and investigate transplacental IgG transfer in a birth cohort in southern Vietnam.

Methods and results

Over 500-paired maternal/infant plasma samples were evaluated for presence of anti-S. sonnei-O IgG and IgM. Longitudinal plasma samples allowed for the estimation of the median half-life of maternal anti-S. sonnei-O IgG, which was 43 days (95% confidence interval: 41–45 days). Additionally, half of infants lacked a detectable titer by 19 weeks of age. Lower cord titers were associated with greater increases in S. sonnei IgG over the first year of life, and the incidence of S. sonnei seroconversion was estimated to be 4/100 infant years. Maternal IgG titer, the ratio of antibody transfer, the season of birth and gestational age were significantly associated with cord titer.

Conclusions

Maternal anti-S. sonnei-O IgG is efficiently transferred across the placenta and anti-S. sonnei-O maternal IgG declines rapidly after birth and is undetectable after 5 months in the majority of children. Preterm neonates and children born to mothers with low IgG titers have lower cord titers and therefore may be at greater risk of seroconversion in infancy.

Influenza D virus infection in Mississippi beef cattle

A new member of the Orthomyxoviridae family, influenza D virus (IDV), was first reported in swine in the Midwest region of the United States. This study aims to extend our knowledge on the IDV epidemiology and to determine the impact of bovine production systems on virus spread. A total of 15 isolates were recovered from surveillance of bovine herds in Mississippi, and two genetic clades of viruses co-circulated in the same herd. Serologic assessment from neonatal beef cattle showed 94% seropositive, and presumed maternal antibody levels were substantially lower in animals over six months of age. Active IDV transmission was shown to occur at locations where young, weaned, and comingled calves were maintained. Serological characterization of archived sera suggested that IDV has been circulating in the Mississippi cattle populations since at least 2004. Continuous surveillance is needed to monitor the evolution and epidemiology of IDV in the bovine population.

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A total of 10 influenza D viruses (IDVs) were recovered from beef cattle at Mississippi.

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2 antigenically distinct clades of viruses co-circulated in the same herd.

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Active IDV transmission occurs among young, weaned, and comingled calves.

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Serological surveillance suggests that IDV has been present in the Mississippi cattle population at least since 2004.

Maternal antibodies and infant immune responses to vaccines

Infants are born with immature immune systems, making it difficult for them to effectively respond to the infectious pathogens encountered shortly after birth. Maternal antibody is actively transported across the placenta and serves to provide protection to the newborn during the first weeks to months of life. However, maternal antibody has been shown repeatedly to inhibit the immune responses of young children to vaccines. The mechanisms for this inhibition are presented and the impact on ultimate immune responses is discussed.

Characterization and protective efficacy in an animal model of a novel truncated rotavirus VP8 subunit parenteral vaccine candidate

The cell-attachment protein VP8* of rotavirus is a potential candidate parenteral vaccine. However, the yield of full-length VP8 protein (VP8*, residues 1-231) expressed in Escherichia coli was low, and a truncated VP8 protein (ΔVP8*, residues 65-231) cannot elicit efficient protective immunity in a mouse model. In this study, tow novel truncated VP8 proteins, VP8-1 (residues 26-231) and VP8-2 (residues 51-231), were expressed in E. coli and evaluated for immunogenicity and protective efficacy, compared with VP8* and ΔVP8*. As well as ΔVP8*, the protein VP8-1 and VP8-2 were successfully expressed in high yield and purified in homogeneous dimeric forms, while the protein VP8* was expressed with lower yield and prone to aggregation and degradation in solution. Although the immunogenicity of the protein VP8*, VP8-1, VP8-2 and ΔVP8* was comparable, immunization of VP8* and VP8-1 elicited significantly higher neutralizing antibody titers than that of VP8-2 and ΔVP8* in mice. Furthermore, when assessed using a mouse maternal antibody model, the efficacy of VP8-1 to protect against rotavirus-induced diarrhea in pups was comparable to that of VP8*, both were dramatically higher than that of VP8-2 and ΔVP8*. Taken together, the novel truncated protein VP8-1, with increased yield, improved homogeneity and high protective efficacy, is a viable candidate for further development of a parenterally administrated prophylactic vaccine against rotavirus infection.

Quantifying maternally derived respiratory syncytial virus specific neutralising antibodies in a birth cohort from coastal Kenya

BACKGROUND

Severe respiratory syncytial virus (RSV) disease occurs predominantly in children under 6 months of age. There is no licensed RSV vaccine. Protection of young infants could be achieved by a maternal vaccine to boost titres of passively transferred protective antibodies. Data on the level and kinetics of functional RSV-specific antibody at birth and over the early infant period would inform vaccine product design.

METHODS

From a birth cohort study (2002-2007) in Kilifi, Kenya, 100 participants were randomly selected for whom cord blood and 2 subsequent 3-monthly blood samples within the first year of life, were available. RSV antibodies against the A2 strain of RSV were assayed and recorded as the logarithm (base 2) plaque reduction neutralisation test (PRNT) titre. Analysis by linear regression accounted for within-person clustering.

RESULTS

The geometric mean neutralisation antibody titre was 10.6 (SD: 1.13) at birth with a log-linear decay over the first 6 months of life. The estimated rate of decay was -0.58 (SD: 0.20) log2PRNT titre per month and a half-life of 36 days. There was no significant interaction between cord titre and rate of decay with age. Mean cord titres rose and fell in a pattern temporally tracking community virus transmission.

CONCLUSIONS

In this study population, RSV neutralising antibody titres decay approximately two-fold every one month. The rate of decay varies widely by individual but is not related to titre at birth. RSV specific cord titres vary seasonally, presumably due to maternal boosting.

Overcoming the susceptibility gap between maternal antibody disappearance and auto-antibody production

In the first 10-14 days of a chick's life, protection is conferred by maternal antibodies. Further broiler protection is achieved by active vaccination. However, the high level of maternal antibodies interferes with the induction of an effective immune response by vaccination at a young age. As a result, there is a gap between the reduction in protective maternal antibodies and elevation of self-produced antibodies following active vaccination. The major aim of this study was to test an approach consisting of passive and active vaccination to overcome this gap and to provide continuous resistance to infectious viral diseases during the broiler's growth period. Newcastle disease virus (NDV), which is one of the world's most prevalent infectious diseases of poultry, was tested as a model. Following subcutaneous injection of 18 hemagglutination-inhibiting (HI) units of anti-NDV immunoglobulin Y per 1-day-old chick, protective log2 antibody titers above 4 could be detected to at least 17 days of age. The combination of passive immunization on day 1 of age with attenuated live vaccination on day 10 led to high protective titers throughout the entire growth period, up to 41 days of age. Moreover, the HI titers in the group of birds immunized with the combined vaccination were significantly more homogeneous than those in the group vaccinated only with live virus. Thus, full protection against NDV of all broilers in flock during their entire growth period was achieved by a vaccination regime that combines passive immunization and live vaccination.

A tetravalent alphavirus-vector based dengue vaccine provides effective immunity in an early life mouse model

Dengue viruses (DENV1-4) cause 390 million clinical infections every year, several hundred thousand of which progress to severe hemorrhagic and shock syndromes. Preexisting immunity resulting from a previous DENV infection is the major risk factor for severe dengue during secondary heterologous infections. During primary infections in infants, maternal antibodies pose an analogous risk. At the same time, maternal antibodies are likely to prevent induction of endogenous anti-DENV antibodies in response to current live, attenuated virus (LAV) vaccine candidates. Any effective early life dengue vaccine has to overcome maternal antibody interference (leading to ineffective vaccination) and poor induction of antibody responses (increasing the risk of severe dengue disease upon primary infection). In a previous study, we demonstrated that a non-propagating Venezuelan equine encephalitis virus replicon expression vector (VRP), expressing the ectodomain of DENV E protein (E85), overcomes maternal interference in a BALB/c mouse model. We report here that a single immunization with a tetravalent VRP vaccine induced NAb and T-cell responses to each serotype at a level equivalent to the monovalent vaccine components, suggesting that this vaccine modality can overcome serotype interference. Furthermore, neonatal immunization was durable and could be boosted later in life to further increase NAb and T-cell responses. Although the neonatal immune response was lower in magnitude than responses in adult BALB/c mice, we demonstrate that VRP vaccines generated protective immunity from a lethal challenge after a single neonatal immunization. In summary, VRP vaccines expressing DENV antigens were immunogenic and protective in neonates, and hence are promising candidates for safe and effective vaccination in early life.

Improved characteristics and protective efficacy in an animal model of E. coli-derived recombinant double-layered rotavirus virus-like particles

Live rotavirus vaccines that are effective in middle- and high-income countries have been found to be less immunogenic and effective in infants in resource-limited settings. The virus-like particle (VLP) approach is promising for rotavirus vaccine development, but challenges remain for VLP production at large scale. In this study, rotavirus capsid VP2 and VP6 proteins were expressed in Escherichia coli and were assembled with high efficiency into homogeneous single-layered VP6-VLPs or double-layered VP2/6-VLPs (dl2/6-VLPs) through a post-purification assembly process. The dl2/6-VLPs were observed to have better thermal stability and antigenicity. Although the immunogenicity of VP6 trimers, VP6-VLPs and dl2/6-VLPs was comparable, the efficacy of the dl2/6-VLPs to protect against rotavirus-induced diarrhea in pups was significantly higher than that of the trimeric VP6 or the VP6-VLPs when assessed using a mouse maternal antibody model. Taken together, the recombinant dl2/6-VLP antigen, which is highly analogous to rotavirus virion-derived double-layered particles, is a viable candidate for vaccine development and has the potential to be a parenterally administered safe and efficacious rotavirus vaccine.

Maternal antibody induced by recombinant gp85 protein vaccine adjuvanted with CpG-ODN protects against ALV-J early infection in chickens

In this study, the efficacy of a recombinant protein vaccine encoding the gp85 gene from the subgroup J avian leukosis virus (ALV-J) co-administered with cytosine-phosphate-guanine oligodeoxynucleotide (CpG-ODN) or Freund's adjuvants was investigated for the protection against early ALV-J infection in chickens. The gp85 gene from ALV-J was amplified using polymerase chain reaction (PCR), and the recombinant protein was expressed in Escherichia coli. The purified recombinant protein was injected intramuscularly into the breeder hens along with CpG-ODN or Freund's adjuvants, and the antibodies in the serum were assayed regularly post inoculation. The fertilized eggs from the vaccinated hens were hatched, the hatched chickens were challenged with 10(2.2) 50% tissue culture infective dose (TCID50) ALV-J on 1 day, and the maternal antibodies in the hatched chickens were examined regularly before and after the challenge. The viremia was determined weekly, and a histopathological analysis of the immunosuppressive lesions was performed. The results suggest that the gp85 recombinant protein was successfully prepared and was inoculated with CpG-ODN adjuvant into breeder hens to induce serological antibody against ALV-J in the hens and in the hatched chickens. The positive maternal antibodies in the hatched chickens provided effective protection for most chickens against viremia and dramatically decreased the number of immunosuppressive lesions; these protective effects were better than those of the gp85 recombinant protein plus Freund's adjuvant. The data will provide a scientific basis for the application of the ALV-J subunit vaccine to control ALV-J infection in chicken flocks.