Risk Factors Associated with Survival Following Ganciclovir Prophylaxis through Day +100 in Cytomegalovirus At-Risk Pediatric Allogeneic Stem Cell Transplantation Recipients: Development of Cytomegalovirus Viremia Associated with Significantly Decreased 1-Year Survival.

Cytomegalovirus (CMV) reactivation is a major cause of morbidity and nonrelapse mortality (NRM) in pediatric allogeneic stem cell transplantation (alloSCT) recipients. Approximately 80% of CMV seropositive alloHCT recipients will experience CMV reactivation without prophylaxis. The impacts of ganciclovir prophylaxis and subsequent CMV viremia on 1-year survival and 1-year NRM are unknown. The primary objective of this study was to determine the effect of CMV viremia on the probability of 1-year survival and 1-year NRM in pediatric alloSCT recipients receiving 100 days of ganciclovir prophylaxis. The secondary objective was to determine the effect of other risk factors on 1-year survival and 1-year NRM. All patients age 0 to 26 years who underwent alloSCT between June 2011 and May 2020 and received ganciclovir prophylaxis for 100 days at Westchester Medical Center, an academic medical center, were analyzed. Ganciclovir was administered to at-risk alloSCT recipients (donor and or recipient CMV+ serostatus) as 5 mg/kg every 12 hours from the first day of conditioning through day -1 (recipient CMV+ only) followed by 6 mg/kg every 24 hours on Monday through Friday beginning on the day of an absolute neutrophil count >750/mm3 and continuing through day +100. National Cancer Institute Common Terminology Criteria for Adverse Events 5.0 criteria were used to grade toxicity. NRM was analyzed using competing survival analysis with relapse death as a competing event. The log-rank and Gray tests were performed to compare the 1-year survival probabilities and NRM cumulative incidence between patients who experienced CMV viremia post-alloSCT and those who did not. Univariate Cox regression analysis was performed for the following risk factors: CMV viremia, donor source, sex, malignant disease, disease risk index, conditioning intensity, receipt of rabbit antithymocyte globulin (rATG)/alemtuzumab, graft-versus-host disease (GVHD) prophylaxis, CMV donor/recipient serostatus, grade II-IV acute GVHD, and grade 3/4 neutropenia necessitating discontinuation of ganciclovir, treating the last 3 factors as time-dependent covariates. Those with P values < .2 were included in the multivariate Cox regression analysis. Eighty-four alloSCT recipients (41 males, 43 females; median age, 10.8 years [range, .4 to 24.4 years]) were analyzed. Multivariate analysis showed significantly lower 1-year survival and significantly higher 1-year NRM in patients who developed CMV viremia compared to those who did not (P = .0036). No other risk factors were significantly associated with 1-year survival or 1-year NRM. One-year survival was significantly decreased and 1-year NRM was significantly increased in pediatric alloSCT recipients who developed CMV viremia following ganciclovir prophylaxis. No other risk factors were found to be associated with 1-year survival or 1-year NRM. Alternative CMV prophylaxis regimens that reduce CMV viremia should be investigated in pediatric alloSCT recipients at risk for CMV infection.

Comparison of heterologous prime-boost immunization strategies with DNA and recombinant vaccinia virus co-expressing GP3 and GP5 of European type porcine reproductive and respiratory syndrome virus in pigs.

Vaccination is principally used to control and treat porcine reproductive and respiratory syndrome virus (PRRSV) infection. This study investigated immunogenicity and protective efficacy of heterologous prime-boost regimens in pigs, including recombinant DNA and vaccinia virus vectors coexpressing PRRSV European genotype (EU) isolate GP3 and GP5: group A, pVAX1-EU-GP3-GP5 prime and rddVTT-EU-GP3-GP5 boost; group B, rddVTT-EU-GP3-GP5 prime and pVAX1-EU-GP3-GP5 boost; group C, empty vector pVAX1; group D, E3L gene-deleted vaccinia virus E3L- VTT. Vaccine efficacy was tested in an EU-type PRRSV (Lelystad virus strain) challenge pig model based on evaluating PRRSV-specific antibody responses, neutralizing antibodies, cytokines, T lymphocyte proliferation, CD4+ and CD8+ T lymphocytes, clinical symptoms, viremia and tissue virus loads. Plasmid DNA was delivered as chitosan-DNA nanoparticles, and Quil A (Quillaja) was used to increase vaccine efficiency. All piglets were boosted 21 days post the initial inoculation (dpi) and then challenged 14 days later. At 14, 21, 28 and 35 dpi, groups A and B developed significantly higher PRRSV-specific antibody responses compared with control groups C and D. Two weeks after the boost, significant differences in neutralizing antibody and IFN-γ levels were observed between groups A, C, D and B. At 49 dpi, groups A and B had markedly increased peripheral blood CD3+CD4+ T cell levels. Following virus challenge, group A showed viremia, but organ virus loads were lower than those in other groups. Thus, a heterologous prime-boost vaccine regimen (rddVTT-EU-GP3-GP5 prime, pVAX1-EU-GP3-GP5 boost) can improve humoral- and cell-mediated immune responses to provide resistance to EU-type PRRSV infection in vivo.

Evaluation of dynamics of immune responses and protective efficacy in piglets immunized with an inactivated porcine reproductive and respiratory syndrome vaccine candidate.

Porcine Reproductive and Respiratory Syndrome (PRRS) is an important viral disease of swine that causes significant mortality in piglets and production losses in adult pigs. In this study, we investigated the protective efficacy of an inactivated PRRS virus vaccine candidate and evaluated the differences in PRRSV specific anamnestic response in piglets when challenged with live PRRSV at two different intervals post-immunization. Six-week-old piglets were immunized intramuscularly with an inactivated, Montanide ISA-206 adjuvanted Indian PRRSV isolate, followed by a booster dose at 21 days post-immunization. Homologous live PRRS virus challenge was done on 60 and 180 days post-booster (dpb). We assessed humoral and cell-mediated immune responses at various intervals post-immunization and after challenge. Viraemia, virus shedding in nasal secretions and lung lesion scores were studied to assess the efficacy of the vaccine candidate. All the immunized pigs developed PRRSV-specific antibodies upon booster dose administration. Neutralizing antibody (NA) titres before challenge, in most animals, ranged between 0 and 4. Potentially protective NA titre of 8 was observed in serum of seven out of the 12 immunized piglets after challenge, across the immunized groups. A significant increase in the mean T-helper, T-cytotoxic, memory or activated T-helper and NK cell populations was observed in immunized piglets challenged at 180 dpb, from 4 to 11 dpc, 5 to 11 dpc, 5 to 7 dpc and 6 to 11 dpc, respectively as compared to the challenge controls. Protective efficacy of the inactivated PRRSV antigen against the homologous virus challenge was evidenced by earlier onset of PRRSV specific virus neutralizing antibodies and cell mediated immune responses, reduced viremia, nasal virus shedding and severity of lung lesions in immunized piglets as compared to unimmunized controls post-challenge. Our results indicated that the inactivated PRRSV antigen elicited better virus specific anamnestic immune responses in piglets when challenged at six months after the single booster dose, due to age related increase in antigen-specific memory T helper cell responses, as compared to those challenged at 2 months post booster.

Efficacy and safety of preemptive therapy for cytomegalovirus end-organ disease in people living with HIV: a systematic review and meta-analysis.

INTRODUCTION: Cytomegalovirus end-organ-disease (CMV EOD) is still a major cause of debilitating illness in people living with HIV, especially in developing countries. OBJECTIVE: To evaluate the efficacy and safety of preemptive therapy against CMV EOD in HIV-positive adults with CMV viremia. METHODS: Systematic review of clinical trials by searching electronic databases and clinical trial registries, screening and selection of references, data extraction and assessment of risk of bias. The results were presented in a narrative synthesis. Aggregated analyzes for dichotomous outcomes were reported as odds ratios with 95 % Confidence Intervals. RESULTS: Four RTC were included. A reduction in the risk of CMV EOD with preemptive therapy was found OR=0.49 (95 % CI 0.31‒0.76). We did not identify significant differences for all-cause mortality, adverse events, and withdrawal of the therapy secondary to adverse events. CONCLUSIONS: Preemptive therapy could be a potential option for preventing CMV EOD in people living with HIV.

Mammalian Cell-Line-Expressed CD2v Protein of African Swine Fever Virus Provides Partial Protection against the HLJ/18 Strain in the Early Infection Stage.

A cell line expressing the CD2v protein of ASFV was generated. The efficient expression of CD2v protein was determined by immunofluorescence and Western blotting. The CD2v protein was Ni-affinity purified from the supernatant of cell cultures. The CD2v-expressing cells showed properties of hemadsorption, and the secreted CD2v protein exhibited hemagglutinating activity. The antigenicity and immunoprotection ability of CD2v were evaluated by immunizing pigs alone, combined with a cell-line-expressed p30 protein or triple combined with p30 and K205R protein. Immunized pigs were challenged with the highly virulent ASFV strain HLJ/18. Virus challenge results showed that CD2v immunization alone could provide partial protection at the early infection stage. Protein p30 did not show synergistic protection effects in immunization combined with CD2v. Interestingly, immunization with the triple combination of CD2V, p30 and K205R reversed the protection effect. The viremia onset time was delayed, and one pig out of three recovered after the challenge. The pig recovered from ASFV clinical symptoms, the rectal temperature returned to normal levels and the viremia was cleared. The mechanism of this protection effect warrants further investigation.

Equine Polyclonal Antibodies Prevent Acute Chikungunya Virus Infection in Mice.

Chikungunya virus (CHIKV) is a mosquito-transmitted pathogen that causes chikungunya disease (CHIK); the disease is characterized by fever, muscle ache, rash, and arthralgia. This arthralgia can be debilitating and long-lasting, seriously impacting quality of life for years. Currently, there is no specific therapy available for CHIKV infection. We have developed a despeciated equine polyclonal antibody (CHIKV-EIG) treatment against CHIKV and evaluated its protective efficacy in mouse models of CHIKV infection. In immunocompromised (IFNAR-/-) mice infected with CHIKV, daily treatment for five consecutive days with CHIKV-EIG administered at 100 mg/kg starting on the day of infection prevented mortality, reduced viremia, and improved clinical condition as measured by body weight loss. These beneficial effects were seen even when treatment was delayed to 1 day after infection. In immunocompetent mice, CHIKV-EIG treatment reduced virus induced arthritis (including footpad swelling), arthralgia-associated cytokines, viremia, and tissue virus loads in a dose-dependent fashion. Collectively, these results suggest that CHIKV-EIG is effective at preventing CHIK and could be a viable candidate for further development as a treatment for human disease.

Complement contributes to antibody-mediated protection against repeated SHIV challenge.

The first clinical efficacy trials of a broadly neutralizing antibody (bNAb) resulted in less benefit than expected and suggested that improvements are needed to prevent HIV infection. While considerable effort has focused on optimizing neutralization breadth and potency, it remains unclear whether augmenting the effector functions elicited by broadly neutralizing antibodies (bNAbs) may also improve their clinical potential. Among these effector functions, complement-mediated activities, which can culminate in the lysis of virions or infected cells, have been the least well studied. Here, functionally modified variants of the second-generation bNAb 10-1074 with ablated and enhanced complement activation profiles were used to examine the role of complement-associated effector functions. When administered prophylactically against simian-HIV challenge in rhesus macaques, more bNAb was required to prevent plasma viremia when complement activity was eliminated. Conversely, less bNAb was required to protect animals from plasma viremia when complement activity was enhanced. These results suggest that complement-mediated effector functions contribute to in vivo antiviral activity, and that their engineering may contribute to the further improvements in the efficacy of antibody-mediated prevention strategies.

Immunization with a small fragment of the Schmallenberg virus nucleoprotein highly conserved across the Orthobunyaviruses of the Simbu serogroup reduces viremia in SBV challenged IFNAR-/- mice.

Schmallenberg Virus (SBV), an arbovirus from the Peribunyaviridae family and Orthobunyavirus genus, was discovered in late 2011 in Germany and has been circulating in Europe, Asia and Africa ever since. The virus causes a disease associated with ruminants that includes fever, fetal malformation, drop in milk production, diarrhoea and stillbirths, becoming a burden for small and large farms. Building on previous studies on SBV nucleoprotein (SBV-N) as a promising vaccine candidate, we have investigated the possible protein regions responsible for protection. Based on selective truncation of domains designed from the available crystal structure of the SBV-N, we identified both the N-terminal domain (N-term; Met1 - Thr133) and a smaller fragment within (C4; Met1 - Ala58) as vaccine prototypes. Two injections of the N-term and C4 polypeptides protected mice knockout for type I interferon (IFN) receptors (IFNAR-/-) challenged with virulent SBV, opposite to control groups that presented severe signs of morbidity and weight loss. Viremia analyses along with the presence of IFN-γ secreted from splenocytes re-stimulated with the N-terminal region of the protein corroborate that these two portions of SBV-N can be employed as subunit vaccines. Apart from both proteinaceous fragments being easily produced in bacterial cells, the C4 polypeptide shares a high sequence homology (∼87.1 %) with the corresponding region of nucleoproteins of several viruses of the Simbu serogroup, a group of Orthobunyaviruses that comprises SBV and veterinary pathogens like Akabane virus and human infecting viruses like Oropouche. Thus, we propose that this smaller fragment is better suited for vaccine nanoparticle formulation, and it paves the way to further research with other related Orthobunyaviruses.

Evaluation of an Engineered Zika Virus-Like Particle Vaccine Candidate in a Mosquito-Mouse Transmission Model.

The primary route of Zika virus (ZIKV) transmission is through the bite of an infected Aedes mosquito, when it probes the skin of a vertebrate host during a blood meal. Viral particles are injected into the bite site together with mosquito saliva and a complex mixture of other components. Some of them are known to play a key role in the augmentation of the arbovirus infection in the host, with increased viremia and/or morbidity. This vector-derived contribution to the infection is not usually considered when vaccine candidates are tested in preclinical animal models. In this study, we performed a preclinical validation of a promising ZIKV vaccine candidate in a mosquito-mouse transmission model using both Asian and African ZIKV lineages. Mice were immunized with engineered ZIKV virus-like particles and subsequently infected through the bite of ZIKV-infected Aedes aegypti mosquitoes. Despite a mild increase in viremia in mosquito-infected mice compared to those infected through traditional needle injection, the vaccine protected the animals from developing the disease and strongly reduced viremia. In addition, during peak viremia, naive mosquitoes were allowed to feed on infected vaccinated and nonvaccinated mice. Our analysis of viral titers in mosquitos showed that the vaccine was able to inhibit virus transmission from the host to the vector. IMPORTANCE Zika is a mosquito-borne viral disease, causing acute debilitating symptoms and complications in infected individuals and irreversible neuronal abnormalities in newborn children. The primary vectors of ZIKV are Aedes aegypti mosquitoes. Despite representing a significant public health burden with a widespread transmission in many regions of the world, Zika remains a neglected disease with no effective antiviral therapies or approved vaccines. It is known that components of the mosquito bite lead to an enhancement of viral infection and spread, but this aspect is often overlooked when vaccine candidates undergo preclinical validation. In this study, we included mosquitoes as viral vectors, demonstrating the ability of a promising vaccine candidate to protect animals against ZIKV infections after the bite of an infected mosquito and to also prevent its further transmission. These findings represent an additional crucial step for the development of an effective prevention tool for clinical use.

A multivalent polyomavirus vaccine elicits durable neutralizing antibody responses in macaques.

In 2019, there were about 100,000 kidney transplants globally, with more than a quarter of them performed in the United States. Unfortunately, some engrafted organs are lost to polyomavirus-associated nephropathy (PyVAN) caused by BK and JC viruses (BKPyV and JCPyV). Both viruses cause brain disease and possibly bladder cancer in immunosuppressed individuals. Transplant patients are routinely monitored for BKPyV viremia, which is an accepted hallmark of nascent nephropathy. If viremia is detected, a reduction in immunosuppressive therapy is standard care, but the intervention comes with increased risk of immune rejection of the engrafted organ. Recent reports have suggested that transplant recipients with high levels of polyomavirus-neutralizing antibodies are protected against PyVAN. Virus-like particle (VLP) vaccines, similar to approved human papillomavirus vaccines, have an excellent safety record and are known to induce high levels of neutralizing antibodies and long-lasting protection from infection. In this study, we demonstrate that VLPs representing BKPyV genotypes I, II, and IV, as well as JCPyV genotype 2 produced in insect cells elicit robust antibody titers. In rhesus macaques, all monkeys developed neutralizing antibody titers above a previously proposed protective threshold of 10,000. A second inoculation, administered 19 weeks after priming, boosted titers to a plateau of ≥ 25,000 that was maintained for almost two years. No vaccine-related adverse events were observed in any macaques. A multivalent BK/JC VLP immunogen did not show inferiority compared to the single-genotype VLP immunogens. Considering these encouraging results, we believe a clinical trial administering the multivalent VLP vaccine in patients waiting to receive a kidney transplant is warranted to evaluate its ability to reduce or eliminate PyVAN.

Neotropical Sylvatic Mosquitoes and Aedes aegypti Are Not Competent to Transmit 17DD Attenuated Yellow Fever Virus from Vaccinated Viremic New World Non-Human Primates.

Beside humans, thousands of non-human primates (NHPs) died during the recent outbreak caused by the yellow fever virus (YFV) in Brazil. Vaccination of NHPs against YFV with the YF 17DD attenuated virus has emerged as a public health strategy, as it would reduce sylvatic transmission while also preserving endangered susceptible species. The hypothesis of establishing an uncontrolled transmission of this attenuated virus in nature was raised. We assessed vector competence of four sylvatic mosquito species, Haemagogus leucocelaenus, Haemagogus janthinomys/capricornii, Sabethes albiprivus, and Sabethes identicus, as well as the urban vector Aedes aegypti for YF 17DD attenuated vaccine virus when fed directly on eleven viremic lion tamarins or artificially challenged with the same virus. No infection was detected in 689 mosquitoes engorged on viremic lion tamarins whose viremia ranged from 1.05 × 103 to 6.61 × 103 FFU/mL, nor in those artificially taking ≤ 1 × 103 PFU/mL. Low viremia presented by YF 17DD-vaccinated New World NHPs combined with the low capacity and null dissemination ability in sylvatic and domestic mosquitoes of this attenuated virus suggest no risk of its transmission in nature. Thus, vaccination of captive and free-living NHPs against YFV is a safe public health strategy.

Dual-Targeting Polymer Nanoparticles Efficiently Deliver DNA Vaccine and Induce Robust Prophylactic Immunity against Spring Viremia of Carp Virus Infection.

Spring viremia of carp virus (SVCV) is highly contagious and lethal to most cyprinid fish, causing serious economic losses to the carp aquaculture industry. Although DNA vaccines can generate long-term humoral and cellular immune responses, which provide protective immunity against SVCV, the major drawback of DNA vaccines is their low immunogenicity in clinical tests. Here, we construct a dual-targeted polymer DNA vaccine delivery platform (MCS-PCHG) by using mannosylated chitosan to encapsulate the poly(d,l-lactide-co-glycolide)-loaded DNA vaccine containing the heavy-chain CH3 region (CH3) of common carp IgM and the antigenic domain (G131c). The developed nanovaccine delivery platform showed good biocompatibility in vivo and in vitro. With the modification of the mannose moiety and the modification of CH3, the constructed MCS-PCHG could efficiently activate the maturation of antigen-presenting cells. Moreover, we observe significantly high level of immune-related genes expression, serum antigen-specific IgM, SVCV-neutralizing antibody titers in fish vaccinated with MCS-PCHG. Next, the protective efficacy of MCS-PCHG was further evaluated by challenge test. The highest survival rate (ca. 84%) was observed in fish vaccinated with MCS-PCHG after challenging with SVCV. This study presents a novel design for smart, dual-targeted polymer nanoparticles, which are inherently biocompatible, promising for targeted vaccine delivery. IMPORTANCE Spring viremia of carp virus (SVCV) affects global cyprinid fish farming industry, with no available commercial vaccine. Herein, we developed a dual-targeting polymer nanovaccine (MCS-PCHG) by using mannose and common carp IgM heavy chain CH3 region (CH3) as antigen presenting cell (APCs) recognition moiety, attaining the effective delivery of antigen. This dual-targeting polymer vaccine can efficiently activate the APCs, and further induce robust and durable adaptive immune response with good protection against SVCV infection. Our study provides valuable theoretical basis for developing efficient vaccine against infectious diseases in aquaculture.

Protective immunity against spring viremia of carp virus by mannose modified chitosan loaded DNA vaccine.

Spring viremia of carp virus (SVCV) usually be considered as one of the serious in viral diseases of aquaculture, and DNA vaccine with novel delivery mechanism or adjuvant has proven to be a promising and effective strategy to control aquatic animal diseases. In this study, the mannose-modified chitosan, a carrier system for vaccine delivery, were used to developed a chitosan-encapsulated DNA vaccine (CS-M-G) against SVCV, then investigated immune response induced by the vaccine. Our results showed that CS-M-G was confirmed the spherical or elliptical with even distribution and ranging from approximately 50 to 150 nm in size, the expression of the antigen gene could still be detected after 21 d post vaccination. The CS-M-G induces the highest antibody levels in the 20 µg dose group which is about 3 times than naked plasmid group at 21 d post vaccination, and still hold a higher level than control group at 28 d post vaccination. On the side, strongest protection with relative percent survival of 62.1% in the 20 µg CS-M-G group, which could produce significantly higher enzyme activities and up-regulated expression of immune-associated genes than control group. Thus, our results indicate that DNA vaccine loaded with mannose-modified chitosan induces strong immune response and provided an effective protection against SVCV infection, may be helpful and extended for developing more aquatic animal vaccines in the future.

Immunization with Virus-Like Particle Vaccine Protects Rabbits against Hepatitis E-3 Virus Infection.

Here, rabbits were immunized with a virus-like particle (VLP) vaccine prepared by expressing 239 amino acids of the swine hepatitis E virus (HEV)-3 capsid protein using a baculovirus system. Thirty specific-pathogen-free rabbits were divided into five groups (negative and positive control and 10, 50, and 100 µg VLP-vaccinated). Positive control group rabbits showed viremia and fecal viral shedding, whereas rabbits vaccinated with 10 µg VLP showed transient fecal viral shedding, and rabbits vaccinated with 50 and 100 µg VLP did not show viremia or fecal viral shedding. Serum anti-HEV antibody titers increased in a dose-dependent manner. Anti-HEV antibody titers were significantly higher (p < 0.05) in 100 µg VLP-vaccinated rabbits than in the negative control rabbits at week 4. Anti-HEV antibody titers were significantly higher in 50 and 10 µg VLP-vaccinated rabbits than in the negative control rabbits at weeks 8 and 11, respectively. Serum IFN-γ and IL-12 levels were significantly higher (p < 0.01) in rabbits vaccinated with 50 and 100 µg VLP than in the negative control rabbits at weeks 4 and 6. Liver tissues of 50 and 100 µg VLP-vaccinated rabbits displayed significantly less (p < 0.05) fibrosis than those of the positive control rabbits. The prepared VLP vaccine demonstrated dose-dependent immunogenicity sufficient for inducing anti-HEV antibody production, thus protecting rabbits against swine HEV-3.

Phagocytosis by an HIV antibody is associated with reduced viremia irrespective of enhanced complement lysis.

Increasingly, antibodies are being used to treat and prevent viral infections. In the context of HIV, efficacy is primarily attributed to dose-dependent neutralization potency and to a lesser extent Fc-mediated effector functions. It remains unclear whether augmenting effector functions of broadly neutralizing antibodies (bNAbs) may improve their clinical potential. Here, we use bNAb 10E8v4 targeting the membrane external proximal region (MPER) to examine the role of antibody-mediated effector and complement (C') activity when administered prophylactically against SHIV challenge in rhesus macaques. With sub-protective dosing, we find a 78-88% reduction in post-acute viremia that is associated with 10E8v4-mediated phagocytosis acting at the time of challenge. Neither plasma nor tissue viremic outcomes in vivo is improved with an Fc-modified variant of 10E8v4 enhanced for C' functions as determined in vitro. These results suggest that effector functions inherent to unmodified 10E8v4 contribute to efficacy against SHIVSF162P3 in the absence of plasma neutralizing titers, while C' functions are dispensable in this setting, informing design of bNAb modifications for improving protective efficacy.

Potent anti-viral activity of a trispecific HIV neutralizing antibody in SHIV-infected monkeys.

Broadly neutralizing antibodies (bNAbs) represent an alternative to drug therapy for the treatment of HIV-1 infection. Immunotherapy with single bNAbs often leads to emergence of escape variants, suggesting a potential benefit of combination bNAb therapy. Here, a trispecific bNAb reduces viremia 100- to 1000-fold in viremic SHIV-infected macaques. After treatment discontinuation, viremia rebounds transiently and returns to low levels, through CD8-mediated immune control. These viruses remain sensitive to the trispecific antibody, despite loss of sensitivity to one of the parental bNAbs. Similarly, the trispecific bNAb suppresses the emergence of resistance in viruses derived from HIV-1-infected subjects, in contrast to parental bNAbs. Trispecific HIV-1 neutralizing antibodies, therefore, mediate potent antiviral activity in vivo and may minimize the potential for immune escape.

A Vaccine Based on the A/ASIA/G-VII Lineage of Foot-and-Mouth Disease Virus Offers Low Levels of Protection against Circulating Viruses from the A/ASIA/Iran-05 lineage.

The recent emergence and circulation of the A/ASIA/G-VII (A/G-VII) lineage of foot-and-mouth disease virus (FMDV) in the Middle East has resulted in the development of homologous vaccines to ensure susceptible animals are sufficiently protected against clinical disease. However, a second serotype A lineage called A/ASIA/Iran-05 (A/IRN/05) continues to circulate in the region and it is therefore imperative to ensure vaccine strains used will protect against both lineages. In addition, for FMDV vaccine banks that usually hold a limited number of strains, it is necessary to include strains with a broad antigenic coverage. To assess the cross protective ability of an A/G-VII emergency vaccine (formulated at 43 (95% CI 8-230) PD50/dose as determined during homologous challenge), we performed a heterologous potency test according to the European Pharmacopoeia design using a field isolate from the A/IRN/05 lineage as the challenge virus. The estimated heterologous potency in this study was 2.0 (95% CI 0.4-6.0) PD50/dose, which is below the minimum potency recommended by the World Organisation for Animal Health (OIE). Furthermore, the cross-reactive antibody titres against the heterologous challenge virus were poor (≤log10 0.9), even in those cattle that had received the full dose of vaccine. The geometric mean r1-value was 0.2 (95% CI 0.03-0.8), similar to the potency ratio of 0.04 (95% CI 0.004-0.3). Vaccination decreased viraemia and virus excretion compared to the unvaccinated controls. Our results indicate that this A/G-VII vaccine does not provide sufficient protection against viruses belonging to the A/IRN/05 lineage and therefore the A/G-VII vaccine strain cannot replace the A/IRN/05 vaccine strain but could be considered an additional strain for use in vaccines and antigen banks.

Anti-Drug Antibodies in Pigtailed Macaques Receiving HIV Broadly Neutralising Antibody PGT121.

Broadly neutralising antibodies (bNAbs) may play an important role in future strategies for HIV control. The development of anti-drug antibody (ADA) responses can reduce the efficacy of passively transferred bNAbs but the impact of ADA is imperfectly understood. We previously showed that therapeutic administration of the anti-HIV bNAb PGT121 (either WT or LALA version) controlled viraemia in pigtailed macaques with ongoing SHIV infection. We now report on 23 macaques that had multiple treatments with PGT121. We found that an increasing number of intravenous doses of PGT121 or human IgG1 isotype control antibodies (2-4 doses) results in anti-PGT121 ADA induction and low plasma concentrations of PGT121. ADA was associated with poor or absent suppression of SHIV viremia. Notably, ADA within macaque plasma recognised another human bNAb 10E8 but did not bind to the variable domains of PGT121, suggesting that ADA were primarily directed against the constant regions of the human antibodies. These findings have implications for the development of preclinical studies examining multiple infusions of human bNAbs.

Simultaneous Infection With Porcine Reproductive and Respiratory Syndrome and Influenza Viruses Abrogates Clinical Protection Induced by Live Attenuated Porcine Reproductive and Respiratory Syndrome Vaccination.

The porcine respiratory disease complex (PRDC) is responsible for significant economic losses in the pig industry worldwide. Porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza virus are major viral contributors to PRDC. Vaccines are cost-effective measures for controlling PRRS, however, their efficacy in the context of co-infections has been poorly investigated. In this study, we aimed to determine the effect of PRRSV-2 and swine influenza H3N2 virus co-infection on the efficacy of PRRSV modified live virus (MLV) vaccination, which is widely used in the field. Following simultaneous challenge with contemporary PRRSV-2 and H3N2 field isolates, we found that the protective effect of PRRS MLV vaccination on clinical disease and pathology was abrogated, although viral load was unaffected and antibody responses were enhanced. In contrast, co-infection in non-immunized animals reduced PRRSV-2 viremia and H3N2 virus load in the upper respiratory tract and potentiated T cell responses against both PRRSV-2 and H3N2 in the lung. Further analysis suggested that an upregulation of inhibitory cytokines gene expression in the lungs of vaccinated pigs may have influenced responses to H3N2 and PRRSV-2. These findings provide important insights into the effect of viral co-infections on PRRS vaccine efficacy that may help identify more effective vaccination strategies against PRDC in the field.

Safety and efficacy of a Bluetongue inactivated vaccine (serotypes 1 and 4) in sheep.

A new inactivated vaccine against Bluetongue virus (BTV) serotypes 1 and 4, was developed from field isolates. Safety and efficacy of the vaccine were evaluated in sheep by serological monitoring and virus nucleic acid detection after experimental infection of vaccinated animals. Seroconversion was observed in vaccinated animals at day 14 post vaccination (pv) with neutralizing antibody titer of 1.9 and 1.8 for serotypes 1 and 4, respectively. The titer increase significantly after the booster reaching 2.7 and persist one year >1.5 for both serotypes. After challenge with virulent isolates, vireamia was recorded in control animals, as evident by q-PCR with threshold cycles (Ct) ranging from 24 to 31 and peaked at day 10 post challenge, while no vireamia was detected in vaccinated animals. Vaccinated sheep were fully protected against the disease and infection.