Human parainfluenza virus 3 vaccine candidates attenuated by codon-pair deoptimization are immunogenic and protective in hamsters.

Human parainfluenza virus type 3 (HPIV3) is a major pediatric respiratory pathogen lacking available vaccines or antiviral drugs. We generated live-attenuated HPIV3 vaccine candidates by codon-pair deoptimization (CPD). HPIV3 open reading frames (ORFs) encoding the nucleoprotein (N), phosphoprotein (P), matrix (M), fusion (F), hemagglutinin-neuraminidase (HN), and polymerase (L) were modified singly or in combination to generate 12 viruses designated Min-N, Min-P, Min-M, Min-FHN, Min-L, Min-NP, Min-NPM, Min-NPL, Min-PM, Min-PFHN, Min-MFHN, and Min-PMFHN. CPD of N or L severely reduced growth in vitro and was not further evaluated. CPD of P or M was associated with increased and decreased interferon (IFN) response in vitro, respectively, but had little effect on virus replication. In Vero cells, CPD of F and HN delayed virus replication, but final titers were comparable to wild-type (wt) HPIV3. In human lung epithelial A549 cells, CPD F and HN induced a stronger IFN response, viral titers were reduced 100-fold, and the expression of F and HN proteins was significantly reduced without affecting N or P or the relative packaging of proteins into virions. Following intranasal infection in hamsters, replication in the nasal turbinates and lungs tended to be the most reduced for viruses bearing CPD F and HN, with maximum reductions of approximately 10-fold. Despite decreased in vivo replication (and lower expression of CPD F and HN in vitro), all viruses induced titers of serum HPIV3-neutralizing antibodies similar to wt and provided complete protection against HPIV3 challenge. In summary, CPD of HPIV3 yielded promising vaccine candidates suitable for further development.

Safety and Immunogenicity of an mRNA-Based hMPV/PIV3 Combination Vaccine in Seropositive Children.

OBJECTIVES: Human metapneumovirus (hMPV) and parainfluenza virus type 3 (PIV3) are common respiratory illnesses in children. The safety and immunogenicity of an investigational mRNA-based vaccine, mRNA-1653, encoding membrane-anchored fusion proteins of hMPV and PIV3, was evaluated in hMPV/PIV3-seropositive children. METHODS: In this phase 1b randomized, observer-blind, placebo-controlled, dose-ranging study, hMPV/PIV3-seropositive children were enrolled sequentially into 2 dose levels of mRNA-1653 administered 2 months apart; children aged 12 to 36 months were randomized (1:1) to receive 10-µg of mRNA-1653 or placebo and children aged 12 to 59 months were randomized (3:1) to receive 30-µg of mRNA-1653 or placebo. RESULTS: Overall, 27 participants aged 18 to 55 months were randomized; 15 participants received 10-µg of mRNA-1653 (n = 8) or placebo (n = 7), whereas 12 participants received 30-µg of mRNA-1653 (n = 9) or placebo (n = 3). mRNA-1653 was well-tolerated at both dose levels. The only reported solicited local adverse reaction was tenderness at injection site; solicited systemic adverse reactions included grade 1 or 2 chills, irritability, loss of appetite, and sleepiness. A single 10-µg or 30-µg mRNA-1653 injection increased hMPV and PIV3 neutralizing antibody titers (geometric mean fold-rise ratio over baseline: hMPV-A = 2.9-6.1; hMPV-B = 6.2-13.2; PIV3 = 2.8-3.0) and preF and postF binding antibody concentrations (geometric mean fold-rise ratio: hMPV preF = 5.3-6.1; postF = 4.6-6.5 and PIV3 preF = 13.9-14.2; postF = 11.0-12.1); a second injection did not further increase antibody levels in these seropositive children. Binding antibody responses were generally preF biased. CONCLUSIONS: mRNA-1653 was well-tolerated and boosted hMPV and PIV3 antibody levels in seropositive children aged 12 to 59 months, supporting the continued development of mRNA-1653 or its components for the prevention of hMPV and PIV3.

Human parainfluenza virus type 3 expressing the respiratory syncytial virus pre-fusion F protein modified for virion packaging yields protective intranasal vaccine candidates.

Human respiratory syncytial virus (RSV) and parainfluenza virus type 3 (HPIV3) are among the most common viral causes of childhood bronchiolitis and pneumonia worldwide, and lack effective antiviral drugs or vaccines. Recombinant (r) HPIV3 was modified to express the RSV fusion (F) glycoprotein, the major RSV neutralization and protective antigen, providing a live intranasal bivalent HPIV3/RSV vaccine candidate. This extends previous studies using a chimeric bovine-human PIV3 vector (rB/HPIV3). One advantage is that rHPIV3 expresses all of the HPIV3 antigens compared to only two for rB/HPIV3. In addition, the use of rHPIV3 as vector should avoid excessive attenuation following addition of the modified RSV F gene, which may occur with rB/HPIV3. To enhance its immunogenicity, RSV F was modified (i) to increase the stability of the prefusion (pre-F) conformation and (ii) by replacement of its transmembrane (TM) and cytoplasmic tail (CT) domains with those of HPIV3 F (H3TMCT) to increase incorporation in the vector virion. RSV F (+/- H3TMCT) was expressed from the first (F/preN) or the second (F/N-P) gene position of rHPIV3. The H3TMCT modification dramatically increased packaging of RSV F into the vector virion and, in hamsters, resulted in significant increases in the titer of high-quality serum RSV-neutralizing antibodies, in addition to the increase conferred by pre-F stabilization. Only F-H3TMCT/preN replication was significantly attenuated in the nasal turbinates by the RSV F insert. F-H3TMCT/preN, F/N-P, and F-H3TMCT/N-P provided complete protection against wt RSV challenge. F-H3TMCT/N-P exhibited the most stable and highest expression of RSV F, providing impetus for its further development.

Maternal vaccination with a novel chimeric glycoprotein formulated with a polymer-based adjuvant provides protection from human parainfluenza virus type 3 in newborn lambs.

Human parainfluenza virus 3 (PIV3) and respiratory syncytial virus (RSV) are major causative agents of serious respiratory tract illness in newborns and infants. Maternal vaccination could be a promising approach to provide immediate protection against severe PIV3 and RSV infection in young infants. Previously, we demonstrated that maternal immunization with a subunit vaccine consisting of the RSV fusion (F) protein formulated with TriAdj, an adjuvant consisting of poly(I:C), immune defense regulatory peptide and polyphosphazene, protects newborn lambs from RSV. In the present study we evaluated the protective efficacy of a novel bivalent RSV-PIV3 vaccine candidate, FRipScHN/TriAdj, as a maternal vaccine against PIV3 infection in a neonatal lamb model. This vaccine consists of the pre-fusion form of the RSV F protein linked to the haemagglutinin-neuraminidase (HN) of PIV3, formulated with TriAdj. First, we successfully established PIV3 infection in neonatal lambs. Lambs infected with human PIV3 showed gross pathology, bronchointerstitial pneumonia and viral replication in the lungs. Subsequently, ewes were immunized with FRipScHN/TriAdj. RSV FRipSc- and PIV3 HN-specific antibodies with virus-neutralizing activity were detected in both the serum and the colostrum of the vaccinated ewes. The newborn lambs had RSV- and PIV3- neutralizing antibodies in their serum, which demonstrates that maternal antibodies were transferred to the neonates. At three days of age, the newborn lambs received an intrapulmonary challenge with PIV3. The lung pathology and virus production were significantly reduced in lambs that had received PIV3-specific maternal antibodies compared to lambs born to non-vaccinated ewes. These results suggest that maternal vaccination with a bivalent FRipScHN/TriAdj vaccine might be an effective method to provide protection against both PIV3 and RSV in neonates.

Adenovirus 2, Bordetella bronchiseptica, and Parainfluenza Molecular Diagnostic Assay Results in Puppies After vaccination with Modified Live Vaccines.

BACKGROUND: Canine adenovirus 2, parainfluenza, and Bordetella bronchiseptica cause respiratory disease in dogs, and each has a modified live intranasal vaccine available. Molecular diagnostic assays to amplify specific nucleic acids are available for each of these agents. If positive molecular diagnostic assay results are common after vaccination, the positive predictive value of the diagnostic assays for disease would be decreased. OBJECTIVE: To determine the impact of administration of commercially available modified live topical adenovirus 2, B. bronchiseptica, and parainfluenza vaccine has on the results of a commercially available PCR panel. ANIMALS: Eight puppies from a research breeding facility negative for these pathogens. METHODS: Blinded prospective pilot study. Puppies were vaccinated with a single dose of modified live topical adenovirus 2, B. bronchiseptica, and parainfluenza and parenteral dose of adenovirus 2, canine distemper virus, and parvovirus. Nasal and pharyngeal swabs were collected on multiple days and submitted for PCR assay. RESULTS: Nucleic acids of all 3 organisms contained in the topical vaccine were detected from both samples multiple times through 28 days after vaccination with higher numbers of positive samples detected between days 3 and 10 after vaccination. CONCLUSIONS AND CLINICAL IMPORTANCE: Vaccine status should be considered when interpreting respiratory agent PCR results if modified live vaccines have been used. Development of quantitative PCR and wild-type sequencing are necessary to improve positive predictive value of these assays by distinguishing vaccinate from natural infection.

Safety and infectivity of two doses of live-attenuated recombinant cold-passaged human parainfluenza type 3 virus vaccine rHPIV3cp45 in HPIV3-seronegative young children.

BACKGROUND: Human parainfluenza virus type 3 (HPIV3) is a common cause of upper and lower respiratory tract illness in infants and young children. Live-attenuated cold-adapted HPIV3 vaccines have been evaluated in infants but a suitable interval for administration of a second dose of vaccine has not been defined. METHODS: HPIV3-seronegative children between the ages of 6 and 36 months were randomized 2:1 in a blinded study to receive two doses of 105 TCID50 (50% tissue culture infectious dose) of live-attenuated, recombinant cold-passaged human PIV3 vaccine (rHPIV3cp45) or placebo 6 months apart. Serum antibody levels were assessed prior to and approximately 4-6 weeks after each dose. Vaccine virus infectivity, defined as detection of vaccine-HPIV3 in nasal wash and/or a≥4-fold rise in serum antibody titer, and reactogenicity were assessed on days 3, 7, and 14 following immunization. RESULTS: Forty HPIV3-seronegative children (median age 13 months; range 6-35 months) were enrolled; 27 (68%) received vaccine and 13 (32%) received placebo. Infectivity was detected in 25 (96%) of 26 evaluable vaccinees following doses 1 and 9 of 26 subject (35%) following dose 2. Among those who shed virus, the median duration of viral shedding was 12 days (range 6-15 days) after dose 1 and 6 days (range 3-8 days) after dose 2, with a mean peak log10 viral titer of 3.4 PFU/mL (SD: 1.0) after dose 1 compared to 1.5 PFU/mL (SD: 0.92) after dose 2. Overall, reactogenicity was mild, with no difference in rates of fever and upper respiratory infection symptoms between vaccine and placebo groups. CONCLUSION: rHPIV3cp45 was immunogenic and well-tolerated in seronegative young children. A second dose administered 6 months after the initial dose was restricted in those previously infected with vaccine virus; however, the second dose boosted antibody responses and induced antibody responses in two previously uninfected children.

A replication-incompetent influenza virus bearing the HN glycoprotein of human parainfluenza virus as a bivalent vaccine.

Influenza virus and human parainfluenza virus (HPIV) are major etiologic agents of acute respiratory illness in young children. Inactivated and live attenuated influenza vaccines are approved in several countries, yet no vaccine is licensed for HPIV. We previously showed that a replication-incompetent PB2-knockout (PB2-KO) virus that possesses a reporter gene in the coding region of the PB2 segment can serve as a platform for a bivalent vaccine. To develop a bivalent vaccine against influenza and parainfluenza virus, here, we generated a PB2-KO virus possessing the hemagglutinin-neuraminidase (HN) glycoprotein of HPIV type 3 (HPIV3), a major surface antigen of HPIV, in its PB2 segment. We confirmed that this virus replicated only in PB2-expressing cells and expressed HN. We then examined the efficacy of this virus as a bivalent vaccine in a hamster model. High levels of virus-specific IgG antibodies in sera and IgA, IgG, and IgM antibodies in bronchoalveolar lavage fluids against both influenza virus and HPIV3 were detected from hamsters immunized with this virus. The neutralizing capability of these serum antibodies was also confirmed. Moreover, the immunized hamsters were completely protected from virus challenge with influenza virus or HPIV3. These results indicate that PB2-KO virus expressing the HN of HPIV3 has the potential to be a novel bivalent vaccine against influenza and human parainfluenza viruses.

Intake of specific fatty acids and fat alters growth, health, and titers following vaccination in dairy calves.

Typical fatty acid profiles of milk and milk replacer (MR) differ. Calf MR in the United States are made from animal fat, which are low in short- and medium-chain fatty acids and linolenic acid. Two 56-d trials compared a control MR containing 27% crude protein and formulated with 3 fat and fatty acid compositions. The 3 MR treatments were (1) only animal fat totaling 17% fat (CON), (2) animal fat supplemented with butyrate, medium-chain fatty acids, and linolenic acid using a commercial product (1.25% NeoTec4 MR; Provimi North America, Brookville, OH) totaling 17% fat (fatty acid-supplemented; FA-S), and (3) milk fat totaling 33% fat (MF). The MR were fed at 660 g of dry matter from d 0 to 42 and weaned. Starter (20% crude protein) and water were fed ad libitum for 56 d. Trial 1 utilized Holstein calves (24 female, 24 male) during summer months and trial 2 utilized Holstein calves (48 male) during fall months. Calves (41±1 kg of initial body weight; 2 to 3d of age) were sourced from a single farm and housed in a naturally ventilated nursery without added heat. Calves were in individual pens with straw bedding. Calf was the experimental unit. Data for each trial were analyzed as a completely randomized design with a 3 (MR treatment) × 2 (sex) factorial arrangement of treatments in trial 1 with repeated measures and as a completely randomized design with 3 MR treatments in trial 2 with repeated measures. Preplanned contrast statements of treatments CON versus FA-S and CON versus MF were used to separate means. We found no interactions of MR treatment by sex. Calf average daily gain, hip width change, and feed efficiency differed (CONFA-S). Titers to bovine respiratory parainfluenza-3 and bovine virus diarrhea type 1 (vaccinations to these pathogens were on d 7 and 28) in serum samples taken on d 49 and 56 differed (CONFA-S; CONFA-S; CON>MF). Calves fed FA-S and MF had improved growth and feed efficiency compared with calves fed CON, whereas calves fed FA-S also had improved measurements related to health and immunity.

Evaluation of two chimeric bovine-human parainfluenza virus type 3 vaccines in infants and young children.

Human parainfluenza virus type 3 (HPIV3) is an important cause of lower respiratory tract illness in children, yet a licensed vaccine or antiviral drug is not available. We evaluated the safety, tolerability, infectivity, and immunogenicity of two intranasal, live-attenuated HPIV3 vaccines, designated rHPIV3-N(B) and rB/HPIV3, that were cDNA-derived chimeras of HPIV3 and bovine PIV3 (BPIV3). These were evaluated in adults, HPIV3 seropositive children, and HPIV3 seronegative children. A total of 112 subjects participated in these studies. Both rB/HPIV3 and rHPIV3-N(B) were highly restricted in replication in adults and seropositive children but readily infected seronegative children, who shed mean peak virus titers of 10(2.8) vs. 10(3.7)pfu/mL, respectively. Although rB/HPIV3 was more restricted in replication in seronegative children than rHPIV3-N(B), it induced significantly higher titers of hemagglutination inhibition (HAI) antibodies against HPIV3. Taken together, these data suggest that the rB/HPIV3 vaccine is the preferred candidate for further clinical development.

The cDNA-derived investigational human parainfluenza virus type 3 vaccine rcp45 is well tolerated, infectious, and immunogenic in infants and young children.

BACKGROUND: Human parainfluenza virus type 3 (HPIV3) is an important yet underappreciated cause of lower respiratory tract illness in children, and a licensed vaccine is not yet available. METHODS: A live-attenuated investigational HPIV3 vaccine virus designated rcp45 was derived from cDNA by using reverse genetics. rcp45 is genetically similar to the biologically derived cp45 vaccine virus and contains all of the known attenuating mutations of cp45, but has the advantage of a short, well-characterized passage history. We evaluated the tolerability, infectivity, and immunogenicity of 2 intranasal doses of rcp45 administered 4 to 10 weeks apart in a placebo-controlled, double-blind trial. A total of 45 infants and children between 6 and 36 months of age participated in this study. Tolerability and antibody responses to vaccine or placebo were assessed in all recipients. Infectivity was assessed by quantitation of vaccine virus shedding in a subset of vaccinated children. RESULTS: rcp45 was well tolerated and highly infectious in HPIV3-seronegative children. A second dose of vaccine administered 4 to 10 weeks after the first dose was restricted in replication and did not boost serum antibody responses. The stability of 9 cp45 mutations, including the 6 major attenuating mutations, was examined and confirmed for viral isolates from 10 children. CONCLUSIONS: The level of attenuation and immunogenicity of cDNA-derived rcp45 is comparable to what was previously observed with the biologically derived cp45 vaccine, and preliminary data suggest that the attenuating mutations in this vaccine virus are genetically stable. Continued clinical development of rcp45 is warranted.

A randomized, double-blind, placebo-controlled, phase 1/2a study of the safety and immunogenicity of a live, attenuated human parainfluenza virus type 3 vaccine in healthy infants.

OBJECTIVE: To evaluate the safety, tolerability, immunogenicity, and viral shedding profiles of a recombinant, live, attenuated human parainfluenza virus type 3 (HPIV3) vaccine, rHPIV3cp45, in healthy HPIV3-seronegative infants 6 to <12 months of age. METHODS: In this double-blind, multicenter study, subjects were randomized 2:1 to receive a 10(5)TCID(50) dose of rHPIV3cp45 (n=20) or placebo (n=10) at enrollment and at 2 and 4 months after the first dose. Blood for evaluation of antibody to HPIV3 was collected at baseline and approximately 1 month after each dose. Solicited adverse events (SEs) and unsolicited adverse events (AEs) were collected on days 0-28 after each dose. Nasal wash samples for vaccine virus shedding were collected 3 times after each dose (7-10, 12-18, and 28-34 days post dose) and at unscheduled illness visits. Subjects were followed for 180 days after the last dose. RESULTS: Vaccine virus was shed by 85% of vaccine recipients after dose 1, by 1 subject after dose 2, and was not shed by any subject after dose 3. The highest titer of shed virus was detected on day 7 after dose 1. The attenuation phenotype and the genotype of the vaccine virus were stable in shed virus. Seroresponse (≥ 4-fold rise in HPIV3 antibody from baseline) occurred in 61% of subjects after dose 1 and in 77% after dose 3. Either seroresponse or shedding occurred in 95% of vaccine subjects. Adverse events were similar in vaccine and placebo recipients. CONCLUSION: The safety, shedding, and immunogenicity profiles of rHPIV3cp45 in HPIV3-seronegative infants 6 to <12 months of age support further development of this vaccine.

[Evaluation of the immune response after vaccination against distemper at a mink (Mustela vison) farm in Argentina]. / Observaciones sobre el plan de vacunación contra el distemper en visones (Mustela vison) en un criadero de Argentina.

Distemper virus causes a disease affecting minks with respiratory, gastrointestinal, neurological and skin symptoms and showing high morbidity and mortality, mainly among puppies. It is controlled through immunization, using vaccines that are supplied for mink use. The aim of this work was to determine the seroneutralization titer against the distemper virus at a mink farm in Argentina. The antibody kinetics obtained after vaccination in 27 adult animals, as well as the duration of colostrum-transferred antibodies in 10 puppies were determined. All vaccinated adult minks showed protective titers up to at least 3 months after vaccination, and 37.5% significantly reduced their antibody levels, 12 months after vaccination. Only 20% of the puppies showed protective levels of colostrum-transferred antibodies at the age of 7 weeks, while non-detectable levels of antibodies were found when puppies reached 11 weeks old. Vaccination performed in these puppies at the age of 13 weeks, elicited protective seroneutralization titers. These results show that vaccination induces a satisfactory humoral immune response in our environment, and support the convenience of vaccinating dams annually before the beginning of the breeding season. The vaccination plan in puppies is also discussed.

A novel human parainfluenza virus type 1 (HPIV1) with separated P and C genes is useful for generating C gene mutants for evaluation as live-attenuated virus vaccine candidates.

A novel recombinant human parainfluenza virus type 1 (rHPIV1), rHPIV1-C+P, in which the overlapping open reading frames of the C and P genes were separated in order to introduce mutations into the C gene without affecting P, was generated. Infectious rHPIV1-C+P was readily recovered and replicated as efficiently as HPIV1 wild type (wt) in vitro and in African green monkeys (AGMs). rHPIV1-C+P expressed increased levels of C protein and, surprisingly, activated the type I IFN and apoptosis responses more strongly than HPIV1 wt. rHPIV1-C+P provided a useful backbone for recovering an attenuated P/C gene mutation (Delta 84-85), which was previously unrecoverable, likely due to detrimental effects of the deletion on the P protein. rHPIV1-C(Delta 84-85)+P and an additional mutant, rHPIV1-C(Delta 169-170)+P, were found to replicate to similar titers in vitro and to activate the type I IFN and apoptosis responses to a similar degree as rHPIV1-C+P. rHPIV1-C(Delta 84-85)+P was found to be highly attenuated in AGMs, and all viruses were immunogenic and effective in protecting AGMs against challenge with HPIV1 wt. rHPIV1-C(Delta 84-85)+P will be investigated as a potential live-attenuated vaccine candidate for HPIV1.

Phase-I study MEDI-534, of a live, attenuated intranasal vaccine against respiratory syncytial virus and parainfluenza-3 virus in seropositive children.

A live, attenuated respiratory syncytial virus and parainfluenza virus type 3 vaccine was evaluated in healthy respiratory syncytial virus/parainfluenza virus type 3 seropositive children aged 1 to 9 years. Three cohorts of 40 children were randomized 1:1 to receive 10, 10, or 10 median tissue culture infectious dose50 MEDI-534 vaccine or placebo. The vaccine's safety profile was similar to placebo, no viral shedding was detected, and the vaccine was minimally immunogenic.

Current status of vaccines for parainfluenza virus infections.

Parainfluenza viruses (PIV) have been generally disregarded as pathogens in spite of their importance in pediatric lower respiratory illness. Because PIVs account for 17% of hospitalized illness associated virus isolation, the development of PIV vaccine would be a major advance in preventing lower respiratory tract infection in infants and young children. We will review in detail several PIV vaccine candidates and recent newer approaches to PIV vaccine development. Intranasally administered bovine PIV3 (bPIV3) vaccine and cold-adapted PIV3 vaccine have been evaluated throughout the pediatric age spectrum. BPIV3 does not give a robust response to the heterotypic human strain although seroconversion rate to bPIV3 is 57-65%. However, bPIV3 vaccine is being used as an attenuated backbone for insertion of human PIV3 hemagglutinin-neuraminidase and fusion (F) proteins and a surface protein, F, of respiratory syncytial virus. The effectiveness of this vaccine against both PIV3 and RSV challenge has been demonstrated in African green monkeys. The cold-adapted PIV3 vaccine has been extensively evaluated and is safe and immunogenic in seronegative children with a seroconversion rate of 79%. These promising candidates deserve to enter into efficacy trials both for their ability to prevent PIV3 disease and as a model of protection against respiratory illness by mucosal vaccination.

Development of recombinant Sendai virus vaccines for prevention of human parainfluenza and respiratory syncytial virus infections.

Respiratory syncytial virus (RSV) and human parainfluenza viruses (hPIVs) are the most important causes of hospitalization for viral respiratory tract diseases in infants and young children. Unfortunately, there are currently no licensed vaccines for prevention of these infections. Researchers at St. Jude Children's Research Hospital are now developing Sendai virus (SV), a natural respiratory pathogen of mice, as a Jennerian vaccine for hPIV-1, and as a vaccine backbone for the prevention of RSV and other hPIVs. Unmodified SV is currently being tested in the clinic. Thus far, the vaccine has been well tolerated. Preclinical studies also continue and have demonstrated that intranasal vaccinations with recombinant SV expressing an RSV antigen are sufficient to activate high-magnitude RSV-specific neutralizing B- and T-cell activities in a cotton rat system. Furthermore, vaccinated animals are completely protected against RSV challenges. As clinical safety studies progress, St. Jude Children's Research Hospital researchers are also working to formulate a SV-based cocktail vaccine designed to prevent several hPIV and RSV infections in humans.

Development of a PIV-vectored RSV vaccine: preclinical evaluation of safety, toxicity, and enhanced disease and initial clinical testing in healthy adults.

MEDI-534 is a bivalent live attenuated vaccine candidate against human respiratory syncytial virus (hRSV) and human parainfluenza virus type 3 (hPIV3) that was previously shown to be immunogenic and to protect rodents and African green monkeys from wild-type (wt) hRSV challenge. We performed further preclinical evaluations to address the safety of MEDI-534 prior to human testing. MEDI-534 did not predispose rodents to enhanced RSV disease following wt-RSV challenge, and the tissue tropism of the chimeric virus was confined to the respiratory tract. Representative clinical trial material did not produce toxicity in rats. In adults, MEDI-534 was highly restricted in replication, did not boost RSV and PIV3 antibody titers, and produced no medically significant vaccine-related adverse events thereby warranting further evaluation in pediatric populations.

Sendai virus recombinant vaccine expressing hPIV-3 HN or F elicits protective immunity and combines with a second recombinant to prevent hPIV-1, hPIV-3 and RSV infections.

The human parainfluenza viruses (hPIVs) and respiratory syncytial virus (RSV) are the leading causes of serious respiratory illness in the human pediatric population. Despite decades of research, there are currently no licensed vaccines for either the hPIV or RSV pathogens. Here we describe the testing of hPIV-3 and RSV candidate vaccines using Sendai virus (SeV, murine PIV-1) as a vector. SeV was selected as the vaccine backbone, because it has been shown to elicit robust and durable immune activities in animal studies, and has already advanced to human safety trials as a xenogenic vaccine for hPIV-1. Two new SeV-based hPIV-3 vaccine candidates were first generated by inserting either the fusion (F) gene or hemagglutinin-neuraminidase (HN) gene from hPIV-3 into SeV. The resultant rSeV-hPIV3-F and rSeV-hPIV3-HN vaccines expressed their inserted hPIV-3 genes upon infection. The inoculation of either vaccine into cotton rats elicited binding and neutralizing antibody activities, as well as interferon-gamma-producing T cells. Vaccination of cotton rats resulted in protection against subsequent challenges with either homologous or heterologous hPIV-3. Furthermore, vaccination of cotton rats with a mixture of rSeV-hPIV3-HN and a previously described recombinant SeV expressing the F protein of RSV resulted in protection against three different challenge viruses: hPIV-3, hPIV-1 and RSV. Results encourage the continued development of the candidate recombinant SeV vaccines to combat serious respiratory infections of children.

Long-term protection in hamsters against human parainfluenza virus type 3 following mucosal or combinations of mucosal and systemic immunizations with chimeric alphavirus-based replicon particles.

No licensed vaccines are available to protect against parainfluenza virus type 3 (PIV3), a significant health risk for infants. In search of a safe vaccine, we used an alphavirus-based chimeric vector, consisting of Sindbis virus (SIN) structural proteins and Venezuelan equine encephalitis virus (VEE) replicon RNA, expressing the PIV3 hemagglutinin-neuraminidase (HN) glycoprotein (VEE/SIN-HN). We compared different routes of intramuscular (i.m.), intranasal (i.n.), or combined i.n. and i.m. immunizations with VEE/SIN-HN in hamsters. Six months after the final immunization, all hamsters were protected against live PIV3 i.n. challenge in nasal turbinates and lungs. This protection appeared to correlate with antibodies in serum, nasal turbinates and lungs. This is the first report demonstrating mucosal protection against PIV3 for an extended time following immunizations with an RNA replicon delivery system.