Evaluation of a Live-Attenuated Human Parainfluenza Type 1 Vaccine in Adults and Children

Evaluation of a Live-Attenuated Human Parainfluenza Virus Type 2 Vaccine in Adults and Children

We conducted a phase I clinical trial of the live-attenuated recombinant human parainfluenza virus type 2 (HPIV2) vaccine candidate rHPIV2-15C/948L/∆1724 sequentially in adults, HPIV2-seropositive children, and HPIV2-seronegative children, the target population for vaccination. rHPIV2-15C/948L/∆1724 was appropriately restricted in replication in adults and HPIV2-seropositive children but was overattenuated for HPIV2-seronegative children.

Intracellular immunoglobulin A (icIgA) in protective immunity and vaccines

Virus neutralization at respiratory mucosal surfaces is important in the prevention of infection. Mucosal immunity is mediated mainly by extracellular secretory immunoglobulin A (sIgA) and its role has been well studied. However, the protective role of intracellular specific IgA (icIgA) is less well defined. Initially, in vitro studies using epithelial cell lines with surface expressed polymeric immunoglobulin receptor (pIgR) in transwell culture chambers have shown that icIgA can neutralize influenza, parainfluenza, HIV, rotavirus and measles viruses. This effect appears to involve an interaction between polymeric immunoglobulin A (pIgA) and viral particles within an intracellular compartment, since IgA is transported across the polarized cell. Co-localization of specific icIgA with influenza virus in patients' (virus culture positive) respiratory epithelial cells using well-characterized antisera was initially reported in 2018. This review provides a summary of in vitro studies with icIgA on colocalization and neutralization of the above five viruses. Two other highly significant respiratory infectious agents with severe global impacts viz. SARS-2 virus (CoViD pandemic) and the intracellular bacterium-Mycobacterium tuberculosis-are discussed. Further studies will provide more detailed understanding of the mechanisms and kinetics of icIgA neutralization in relation to viral entry and early replication steps with a specific focus on mucosal infections. This will inform the design of more effective vaccines against infectious agents transmitted via the mucosal route.

Vaccines for the common cold

BACKGROUND

The common cold is a spontaneously remitting infection of the upper respiratory tract, characterised by a runny nose, nasal congestion, sneezing, cough, malaise, sore throat, and fever (usually < 37.8 ºC). Whilst the common cold is generally not harmful, it is a cause of economic burden due to school and work absenteeism. In the United States, economic loss due to the common cold is estimated at more than USD 40 billion per year, including an estimate of 70 million workdays missed by employees, 189 million school days missed by children, and 126 million workdays missed by parents caring for children with a cold. Additionally, data from Europe show that the total cost per episode may be up to EUR 1102. There is also a large expenditure due to inappropriate antimicrobial prescription. Vaccine development for the common cold has been difficult due to antigenic variability of the common cold viruses; even bacteria can act as infective agents. Uncertainty remains regarding the efficacy and safety of interventions for preventing the common cold in healthy people, thus we performed an update of this Cochrane Review, which was first published in 2011 and updated in 2013 and 2017.

OBJECTIVES

To assess the clinical effectiveness and safety of vaccines for preventing the common cold in healthy people.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (April 2022), MEDLINE (1948 to April 2022), Embase (1974 to April 2022), CINAHL (1981 to April 2022), and LILACS (1982 to April 2022). We also searched three trials registers for ongoing studies, and four websites for additional trials (April 2022). We did not impose any language or date restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of any virus vaccine compared with placebo to prevent the common cold in healthy people.

DATA COLLECTION AND ANALYSIS

We used Cochrane's Screen4Me workflow to assess the initial search results. Four review authors independently performed title and abstract screening to identify potentially relevant studies. We retrieved the full-text articles for those studies deemed potentially relevant, and the review authors independently screened the full-text reports for inclusion in the review, recording reasons for exclusion of the excluded studies. Any disagreements were resolved by discussion or by consulting a third review author when needed. Two review authors independently collected data on a data extraction form, resolving any disagreements by consensus or by involving a third review author. We double-checked data transferred into Review Manager 5 software. Three review authors independently assessed risk of bias using RoB 1 tool as outlined in the Cochrane Handbook for Systematic Reviews of Interventions. We carried out statistical analysis using Review Manager 5. We did not conduct a meta-analysis, and we did not assess publication bias. We used GRADEpro GDT software to assess the certainty of the evidence and to create a summary of findings table.  MAIN RESULTS: We did not identify any new RCTs for inclusion in this update. This review includes one RCT conducted in 1965 with an overall high risk of bias. The RCT included 2307 healthy young men in a military facility, all of whom were included in the analyses, and compared the effect of three adenovirus vaccines (live, inactivated type 4, and inactivated type 4 and 7) against a placebo (injection of physiological saline or gelatin capsule). There were 13 (1.14%) events in 1139 participants in the vaccine group, and 14 (1.19%) events in 1168 participants in the placebo group. Overall, we do not know if there is a difference between the adenovirus vaccine and placebo in reducing the incidence of the common cold (risk ratio 0.95, 95% confidence interval 0.45 to 2.02; very low-certainty evidence). Furthermore, no difference in adverse events when comparing live vaccine preparation with placebo was reported. We downgraded the certainty of the evidence to very low due to unclear risk of bias, indirectness because the population of this study was only young men, and imprecision because confidence intervals were wide and the number of events was low. The included study did not assess vaccine-related or all-cause mortality.  AUTHORS' CONCLUSIONS: This Cochrane Review was based on one study with very low-certainty evidence, which showed that there may be no difference between the adenovirus vaccine and placebo in reducing the incidence of the common cold. We identified a need for well-designed, adequately powered RCTs to investigate vaccines for the common cold in healthy people. Future trials on interventions for preventing the common cold should assess a variety of virus vaccines for this condition, and should measure such outcomes as common cold incidence, vaccine safety, and mortality (all-cause and related to the vaccine).

Global burden of acute lower respiratory infection associated with human parainfluenza virus in children younger than 5 years for 2018: a systematic review and meta-analysis

BACKGROUND

Human parainfluenza virus (hPIV) is a common virus in childhood acute lower respiratory infections (ALRI). However, no estimates have been made to quantify the global burden of hPIV in childhood ALRI. We aimed to estimate the global and regional hPIV-associated and hPIV-attributable ALRI incidence, hospital admissions, and mortality for children younger than 5 years and stratified by 0-5 months, 6-11 months, and 12-59 months of age.

METHODS

We did a systematic review of hPIV-associated ALRI burden studies published between Jan 1, 1995, and Dec 31, 2020, found in MEDLINE, Embase, Global Health, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Global Health Library, three Chinese databases, and Google search, and also identified a further 41 high-quality unpublished studies through an international research network. We included studies reporting community incidence of ALRI with laboratory-confirmed hPIV; hospital admission rates of ALRI or ALRI with hypoxaemia in children with laboratory-confirmed hPIV; proportions of patients with ALRI admitted to hospital with laboratory-confirmed hPIV; or in-hospital case-fatality ratios (hCFRs) of ALRI with laboratory-confirmed hPIV. We used a modified Newcastle-Ottawa Scale to assess risk of bias. We analysed incidence, hospital admission rates, and hCFRs of hPIV-associated ALRI using a generalised linear mixed model. Adjustment was made to account for the non-detection of hPIV-4. We estimated hPIV-associated ALRI cases, hospital admissions, and in-hospital deaths using adjusted incidence, hospital admission rates, and hCFRs. We estimated the overall hPIV-associated ALRI mortality (both in-hospital and out-hospital mortality) on the basis of the number of in-hospital deaths and care-seeking for child pneumonia. We estimated hPIV-attributable ALRI burden by accounting for attributable fractions for hPIV in laboratory-confirmed hPIV cases and deaths. Sensitivity analyses were done to validate the estimates of overall hPIV-associated ALRI mortality and hPIV-attributable ALRI mortality. The systematic review protocol was registered on PROSPERO (CRD42019148570).

FINDINGS

203 studies were identified, including 162 hPIV-associated ALRI burden studies and a further 41 high-quality unpublished studies. Globally in 2018, an estimated 18·8 million (uncertainty range 12·8-28·9) ALRI cases, 725 000 (433 000-1 260 000) ALRI hospital admissions, and 34 400 (16 400-73 800) ALRI deaths were attributable to hPIVs among children younger than 5 years. The age-stratified and region-stratified analyses suggested that about 61% (35% for infants aged 0-5 months and 26% for 6-11 months) of the hospital admissions and 66% (42% for infants aged 0-5 months and 24% for 6-11 months) of the in-hospital deaths were in infants, and 70% of the in-hospital deaths were in low-income and lower-middle-income countries. Between 73% and 100% (varying by outcome) of the data had a low risk in study design; the proportion was 46-65% for the adjustment for health-care use, 59-77% for patient groups excluded, 54-93% for case definition, 42-93% for sampling strategy, and 67-77% for test methods. Heterogeneity in estimates was found between studies for each outcome.

INTERPRETATION

We report the first global burden estimates of hPIV-associated and hPIV-attributable ALRI in young children. Globally, approximately 13% of ALRI cases, 4-14% of ALRI hospital admissions, and 4% of childhood ALRI mortality were attributable to hPIV. These numbers indicate a potentially notable burden of hPIV in ALRI morbidity and mortality in young children. These estimates should encourage and inform investment to accelerate the development of targeted interventions.

FUNDING

Bill & Melinda Gates Foundation.

Structural Insight into the Interaction of Sendai Virus C Protein with Alix To Stimulate Viral Budding

The Sendai virus (SeV), belonging to the Respirovirus genus of the family Paramyxoviridae, harbors an accessory protein, named C protein, which facilitates the viral pathogenicity in mice. In addition, the C protein is known to stimulate the budding of virus-like particles through the binding to the host ALG-2 interacting protein X (Alix), a component of the endosomal sorting complexes required for transport (ESCRT) machinery. However, siRNA-mediated gene knockdown studies suggested that neither Alix nor C protein are related to the SeV budding. In the present study, we determined the crystal structure of a complex comprising of the C-terminal half of the C protein (Y3) and the Bro1 domain of Alix at a resolution of 2.2 Å, to investigate the role of the association in the SeV budding. The structure revealed that a novel consensus sequence, LxxW, which is conserved among the Respirovirus C proteins, is important for the Alix-binding. SeV possessing a mutated C protein with a reduced Alix-binding affinity showed impaired virus production, which correlated with the binding affinity. Infectivity analysis showed a 160-fold reduction at 12 h post-infection compared with non-mutated virus, while C protein competes with CHMP4, one subunit of the ESCRT-III complex, on the binding to Alix. Altogether, these results highlight the critical role of C protein in the SeV budding. IMPORTANCE Human parainfluenza virus type I (hPIV1) is a respiratory pathogen affecting in young children, immunocompromised patients, and the elderly, with no available vaccines or antiviral drugs. Sendai virus (SeV), a murine counterpart of hPIV1, has been extensively studied to determine the molecular and biological properties of hPIV1. These viruses possess a multifunctional accessory protein, C protein, which is essential for stimulating the viral reproduction, however, its role in budding remains controversial. In the present study, the crystal structure of the C-terminal half of the SeV C protein associated with the Bro1 domain of Alix, a component of a cell membrane modulating machinery ESCRT, was elucidated. Based on the structure, we designed mutated C proteins with different binding affinity to Alix, and showed that the interaction between C and Alix is vital for the viral budding. These findings provide new insights into the development of a new antiviral drugs against hPIV1.

Engineering of Live Chimeric Vaccines against Human Metapneumovirus

Human metapneumovirus (HMPV) is an important human pathogen that, along with respiratory syncytial virus (RSV), is a major cause of respiratory tract infections in young infants. Development of an effective vaccine against Pneumoviruses has proven to be particularly difficult; despite over 50 years of research in this field, no vaccine against HMPV or RSV is currently available. Recombinant chimeric viruses expressing antigens of other viruses can be generated by reverse genetics and used for simultaneous immunization against more than one pathogen. This approach can result in the development of promising vaccine candidates against HMPV, and several studies have indeed validated viral vectors expressing HMPV antigens. In this review, we summarize current efforts in generating recombinant chimeric vaccines against HMPV, and we discuss their potential optimization based on the correspondence with RSV studies.

Immunity-targeted approaches to the management of chronic and recurrent upper respiratory tract disorders in children

Background

Upper respiratory tract infections (URTIs), including rhinitis, nasopharyngitis, tonsillitis and otitis media (OM), comprise of 88% of total respiratory infections, especially in children. Therefore effective prevention and treatment of RTIs remain a high priority worldwide. Preclinical and clinical data highlight the rationale for the use and effectiveness of immunity‐targeted approaches, including targeted immunisations and non‐specific immunomodulation in the prevention and management of recurrent upper RTIs.

Objective of review

The idea of this review was to summarise the current evidence and address key questions concerning the use of conservative and immunity‐targeted approaches to recurrent and chronic URTIs, with a focus on the paediatric population.

Search strategy/Evaluation method

Literature searches were conducted in March 2017 and updated in September 2017 using: Academic Search Complete; CENTRAL; Health Source: Nursing/Academic Edition; MEDLINE; clinicaltrials.gov; and Cochrane databases. In total, 84 articles were retrieved and reviewed. Two independent researchers focused on primary and secondary endpoints in systematic reviews, meta‐analyses and randomised, controlled trials, using immunity‐directed strategies as the control group or within a subpopulation of larger studies. Existing guidelines and interventional/observational studies on novel applications were also included.

Results

Children are particularly susceptible to RTIs due to the relative immaturity of their immune systems, as well as other potential predisposing factors such as day care attendance and/or toxic environmental factors (eg increased pathogenic microbial exposure and air pollutants). Recurrent URTIs can affect otherwise healthy children, leading to clinical sequelae and complications, including the development of chronic conditions or the need for surgery. Available pre‐clinical and clinical data highlight the rationale for the use and effectiveness of immunity‐targeted approaches, including targeted immunisations (flu and pneumococcal vaccines) and non‐specific immunomodulation (bacterial lysates), in the prevention and management of recurrent croup, tonsillitis, otitis media, recurrent acute rhinosinusitis and chronic rhinosinusitis.

Conclusions

In this review, we summarise the current evidence and provide data demonstrating that some immunity‐targeted strategies, including vaccination and immunomodulation, have proved effective in the treatment and prevention of recurrent and chronic URTIs in children.

The contribution of viruses and bacteria to community-acquired pneumonia in vaccinated children: a casecontrol study

INTRODUCTION

Respiratory pathogens associated with childhood pneumonia are often detected in the upper respiratory tract of healthy children, making their contribution to pneumonia difficult to determine. We aimed to determine the contribution of common pathogens to pneumonia adjusting for rates of asymptomatic detection to inform future diagnosis, treatment and preventive strategies.

METHODS

A case-control study was conducted among children <18 years in Perth, Western Australia. Cases were children hospitalised with radiologically confirmed pneumonia; controls were healthy children identified from outpatient and local immunisation clinics. Nasopharyngeal swabs were collected and tested for 14 respiratory viruses and 6 bacterial species by Polymerase chain reaction (PCR). For each pathogen, adjusted odds ratio (aOR; 95% CI) was calculated using multivariate logistic regression and population-attributable fraction (95% CI) for pneumonia was estimated.

RESULTS

From May 2015 to October 2017, 230 cases and 230 controls were enrolled. At least one respiratory virus was identified in 57% of cases and 29% of controls (aOR: 4.7; 95% CI: 2.8 to 7.8). At least one bacterial species was detected in 72% of cases and 80% of controls (aOR: 0.7; 95% CI: 0.4 to 1.2). Respiratory syncytial virus (RSV) detection was most strongly associated with pneumonia (aOR: 58.4; 95% CI: 15.6 to 217.5). Mycoplasma pneumoniae was the only bacteria associated with pneumonia (aOR: 14.5; 95% CI: 2.2 to 94.8). We estimated that RSV, human metapneumovirus (HMPV), influenza, adenovirus and Mycoplasma pneumoniae were responsible for 20.2% (95% CI: 14.6 to 25.5), 9.8% (5.6% to 13.7%), 6.2% (2.5% to 9.7%), 4% (1.1% to 7.1%) and 7.2% (3.5% to 10.8%) of hospitalisations for childhood pneumonia, respectively.

CONCLUSIONS

Respiratory viruses, particularly RSV and HMPV, are major contributors to pneumonia in Australian children.

T Lymphocytes as Measurable Targets of Protection and Vaccination Against Viral Disorders

Continuous epidemiological surveillance of existing and emerging viruses and their associated disorders is gaining importance in light of their abilities to cause unpredictable outbreaks as a result of increased travel and vaccination choices by steadily growing and aging populations. Close surveillance of outbreaks and herd immunity are also at the forefront, even in industrialized countries, where previously eradicated viruses are now at risk of re-emergence due to instances of strain recombination, contractions in viral vector geographies, and from their potential use as agents of bioterrorism. There is a great need for the rational design of current and future vaccines targeting viruses, with a strong focus on vaccine targeting of adaptive immune effector memory T cells as the gold standard of immunity conferring long-lived protection against a wide variety of pathogens and malignancies. Here, we review viruses that have historically caused large outbreaks and severe lethal disorders, including respiratory, gastric, skin, hepatic, neurologic, and hemorrhagic fevers. To observe trends in vaccinology against these viral disorders, we describe viral genetic, replication, transmission, and tropism, host-immune evasion strategies, and the epidemiology and health risks of their associated syndromes. We focus on immunity generated against both natural infection and vaccination, where a steady shift in conferred vaccination immunogenicity is observed from quantifying activated and proliferating, long-lived effector memory T cell subsets, as the prominent biomarkers of long-term immunity against viruses and their associated disorders causing high morbidity and mortality rates.

Attenuated Human Parainfluenza Virus Type 1 Expressing the Respiratory Syncytial Virus (RSV) Fusion (F) Glycoprotein from an Added Gene: Effects of Prefusion Stabilization and Packaging of RSV F

Human respiratory syncytial virus (RSV) is the most prevalent worldwide cause of severe respiratory tract infection in infants and young children. Human parainfluenza virus type 1 (HPIV1) also causes severe pediatric respiratory illness, especially croup. Both viruses lack vaccines. Here, we describe the preclinical development of a bivalent RSV/HPIV1 vaccine based on a recombinant HPIV1 vector, attenuated by a stabilized mutation, that expresses RSV F protein modified for increased stability in the prefusion (pre-F) conformation by previously described disulfide bond (DS) and hydrophobic cavity-filling (Cav1) mutations. RSV F was expressed from the first or second gene position as the full-length protein or as a chimeric protein with its transmembrane and cytoplasmic tail (TMCT) domains substituted with those of HPIV1 F in an effort to direct packaging in the vector particles. All constructs were recovered by reverse genetics. The TMCT versions of RSV F were packaged in the rHPIV1 particles much more efficiently than their full-length counterparts. In hamsters, the presence of the RSV F gene, and in particular the TMCT versions, was attenuating and resulted in reduced immunogenicity. However, the vector expressing full-length RSV F from the pre-N position was immunogenic for RSV and HPIV1. It conferred complement-independent high-quality RSV-neutralizing antibodies at titers similar to those of wild-type RSV and provided protection against RSV challenge. The vectors exhibited stable RSV F expression in vitro and in vivo In conclusion, an attenuated rHPIV1 vector expressing a pre-F-stabilized form of RSV F demonstrated promising immunogenicity and should be further developed as an intranasal pediatric vaccine.IMPORTANCE RSV and HPIV1 are major viral causes of acute pediatric respiratory illness for which no vaccines or suitable antiviral drugs are available. The RSV F glycoprotein is the major RSV neutralization antigen. We used a rHPIV1 vector, bearing a stabilized attenuating mutation, to express the RSV F glycoprotein bearing amino acid substitutions that increase its stability in the pre-F form, the most immunogenic form that elicits highly functional virus-neutralizing antibodies. RSV F was expressed from the pre-N or N-P gene position of the rHPIV1 vector as a full-length protein or as a chimeric form with its TMCT domain derived from HPIV1 F. TMCT modification greatly increased packaging of RSV F into the vector particles but also increased vector attenuation in vivo, resulting in reduced immunogenicity. In contrast, full-length RSV F expressed from the pre-N position was immunogenic, eliciting complement-independent RSV-neutralizing antibodies and providing protection against RSV challenge.

The Role of Human Parainfluenza Virus Infections in the Immunopathology of the Respiratory Tract

Viral infections are leading causes of both upper and lower airway acute illness in all age groups of healthy persons, and have also been implicated in the acute exacerbations of chronic respiratory disorders like asthma and COPD. Human rhinovirus, respiratory syncytial virus, influenza virus and coronavirus have been considered as the most important respiratory pathogens and relatively little attention has been paid to the role of parainfluenza viruses (hPIVs). Human parainfluenza viruses are single-stranded RNA viruses belonging to the paramyxovirus family that may evoke lower respiratory infections in infants, children and immunocompromised individuals. Among non-immune compromised adults, hPIV infection typically causes mild disease manifested as upper respiratory tract symptoms and is infrequently associated with severe croup or pneumonia. Moreover, hPIV infection may be associated with viral exacerbations of chronic airway diseases, asthma or COPD or chronic rhinosinusitis. In this review, we summarized the basic epidemiology and immunology of hPIVs and addressed the more recent data implicating the role of parainfluenza viruses in the exacerbation of chronic airway disorders.

Clinical and epidemiological characteristics of human parainfluenza virus infections of children in southern Taiwan

BACKGROUND

Human parainfluenza viruses (HPIV) 1-4 had been analyzed as being one of the most frequent causes of hospitalizations for young children with respiratory tract illnesses.

METHODS

This retrospective study was performed from children virologically confirmed as HPIV infection through throat swab or nasopharyngeal aspirates at a tertiary care university hospital, between January 2012 and December 2014. HPIV4 was not checked and analyzed, due to not include in the commercial kit. The demographic, epidemiological, clinical presentations, diagnosis, treatment, outcomes, and laboratory data were analyzed.

RESULTS

Totally 398 cases were enrolled, including 39 (9.8%) of HPIV1, 67 (16.8%) of HPIV2, and 292 (73.4%) of HPIV3. The mean age of HPIV-infected children was 2.9 year-old, and 50.5% were among one to three year-old. A total of 56.8% HPIV3-infected children were among one to three years old, however, no HPIV2-infected children was younger than one year-old. The HPIV1-infected patients were more common to develop wheezing and diagnose as acute bronchiolitis. HPIV2-infected children were more likely to have hoarseness (23.9%), and were associated with croup (25.4%). HPIV3 was isolated from two fatal cases, with neurological underlying diseases.

CONCLUSION

The impact caused by HPIVs infections is significant in hospitalized children. In the current study, our results contribute to the epidemiologic, clinical and laboratory information of HPIV infection in children in the important areas of respiratory tract infection that could support the development of optimization management.

Vaccines for the common cold

BACKGROUND

The common cold is a spontaneously remitting infection of the upper respiratory tract, characterised by a runny nose, nasal congestion, sneezing, cough, malaise, sore throat, and fever (usually < 37.8º C). The widespread morbidity caused by the common cold worldwide is related to its ubiquitousness rather than its severity. The development of vaccines for the common cold has been difficult because of antigenic variability of the common cold virus and the indistinguishable multiple other viruses and even bacteria acting as infective agents. There is uncertainty regarding the efficacy and safety of interventions for preventing the common cold in healthy people. This is an update of a Cochrane review first published in 2011 and previously updated in 2013.

OBJECTIVES

To assess the clinical effectiveness and safety of vaccines for preventing the common cold in healthy people.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (September 2016), MEDLINE (1948 to September 2016), Embase (1974 to September 2016), CINAHL (1981 to September 2016), and LILACS (1982 to September 2016). We also searched three trials registers for ongoing studies and four websites for additional trials (February 2017). We included no language or date restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of any virus vaccines compared with placebo to prevent the common cold in healthy people.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated methodological quality and extracted trial data. We resolved disagreements by discussion or by consulting a third review author.

MAIN RESULTS

We found no additional RCTs for inclusion in this update. This review includes one RCT dating from the 1960s with an overall high risk of bias. The RCT included 2307 healthy participants, all of whom were included in analyses. This trial compared the effect of an adenovirus vaccine against placebo. No statistically significant difference in common cold incidence was found: there were 13 (1.14%) events in 1139 participants in the vaccines group and 14 (1.19%) events in 1168 participants in the placebo group (risk ratio 0.95, 95% confidence interval 0.45 to 2.02; P = 0.90). No adverse events related to the live vaccine were reported. The quality of the evidence was low due to limitations in methodological quality and a wide 95% confidence interval.

AUTHORS' CONCLUSIONS

This Cochrane Review was based on one study with low-quality evidence. We found no conclusive results to support the use of vaccines for preventing the common cold in healthy people compared with placebo. We identified a need for well-designed, adequately powered RCTs to investigate vaccines for the common cold in healthy people. Any future trials on medical treatments for preventing the common cold should assess a variety of virus vaccines for this condition. Outcome measures should include common cold incidence, vaccine safety, and mortality related to the vaccine.

Vaccines in the Prevention of Viral Pneumonia

Pneumonia is of great global public health importance. Viral infections play both direct and indirect parts in its cause across the globe. Influenza is a leading cause of viral pneumonia in both children and adults, and respiratory syncytial virus is increasingly recognized as causing disease at both extremes of age. Vaccination offers the best prospect for prevention but current influenza vaccines do not provide universal and durable protection, and require yearly reformulation. In the future, it is hoped that influenza vaccines will give better and universal protection, and that new vaccines can be found for other causes of viral pneumonia.

Features of Circulating Parainfluenza Virus Required for Growth in Human Airway

Respiratory paramyxoviruses, including the highly prevalent human parainfluenza viruses, cause the majority of childhood croup, bronchiolitis, and pneumonia, yet there are currently no vaccines or effective treatments. Paramyxovirus research has relied on the study of laboratory-adapted strains of virus in immortalized cultured cell lines. We show that findings made in such systems about the receptor interaction and viral fusion requirements for entry and fitness—mediated by the receptor binding protein and the fusion protein—can be drastically different from the requirements for infection in vivo. Here we carried out whole-genome sequencing and genomic analysis of circulating human parainfluenza virus field strains to define functional and structural properties of proteins of circulating strains and to identify the genetic basis for properties that confer fitness in the field. The analysis of clinical strains suggests that the receptor binding-fusion molecule pairs of circulating viruses maintain a balance of properties that result in an inverse correlation between fusion in cultured cells and growth in vivo. Future analysis of entry mechanisms and inhibitory strategies for paramyxoviruses will benefit from considering the properties of viruses that are fit to infect humans, since a focus on viruses that have adapted to laboratory work provides a distinctly different picture of the requirements for the entry step of infection.

Mechanistic information about viral infection—information that impacts antiviral and vaccine development—is generally derived from viral strains grown under laboratory conditions in immortalized cells. This study uses whole-genome sequencing of clinical strains of human parainfluenza virus 3—a globally important respiratory paramyxovirus—in cell systems that mimic the natural human host and in animal models. By examining the differences between clinical isolates and laboratory-adapted strains, the sequence differences are correlated to mechanistic differences in viral entry. For this ubiquitous and pathogenic respiratory virus to infect the human lung, modulation of the processes of receptor engagement and fusion activation occur in a manner quite different from that carried out by the entry glycoprotein-expressing pair of laboratory strains. These marked contrasts in the viral properties necessary for infection in cultured immortalized cells and in natural host tissues and animals will influence future basic and clinical studies.

How I treat respiratory viral infections in the setting of intensive chemotherapy or hematopoietic cell transplantation

The widespread use of multiplex molecular diagnostics has led to a significant increase in the detection of respiratory viruses in patients undergoing cytotoxic chemotherapy and hematopoietic cell transplantation (HCT). Respiratory viruses initially infect the upper respiratory tract and then progress to lower respiratory tract disease in a subset of patients. Lower respiratory tract disease can manifest itself as airflow obstruction or viral pneumonia, which can be fatal. Infection in HCT candidates may require delay of transplantation. The risk of progression differs between viruses and immunosuppressive regimens. Risk factors for progression and severity scores have been described, which may allow targeting treatment to high-risk patients. Ribavirin is the only antiviral treatment option for noninfluenza respiratory viruses; however, high-quality data demonstrating its efficacy and relative advantages of the aerosolized versus oral form are lacking. There are significant unmet needs, including data defining the virologic characteristics and clinical significance of human rhinoviruses, human coronaviruses, human metapneumovirus, and human bocavirus, as well as the need for new treatment and preventative options.

Attenuated Human Parainfluenza Virus Type 1 (HPIV1) Expressing the Fusion Glycoprotein of Human Respiratory Syncytial Virus (RSV) as a Bivalent HPIV1/RSV Vaccine

Live attenuated recombinant human parainfluenza virus type 1 (rHPIV1) was investigated as a vector to express the respiratory syncytial virus (RSV) fusion (F) glycoprotein, to provide a bivalent vaccine against RSV and HPIV1. The RSV F gene was engineered to include HPIV1 transcription signals and inserted individually into three gene locations in each of the two attenuated rHPIV1 backbones. Each backbone contained a single previously described attenuating mutation that was stabilized against deattenuation, specifically, a non-temperature-sensitive deletion mutation involving 6 nucleotides in the overlapping P/C open reading frames (ORFs) (C(Δ170)) or a temperature-sensitive missense mutation in the L ORF (L(Y942A)). The insertion sites in the genome were pre-N (F1), N-P (F2), or P-M (F3) and were identical for both backbones. In vitro, the presence of the F insert reduced the rate of virus replication, but the final titers were the same as the final titer of wild-type (wt) HPIV1. High levels of RSV F expression in cultured cells were observed with rHPIV1-C(Δ170)-F1, -F2, and -F3 and rHPIV1-L(Y942A)-F1. In hamsters, the rHPIV1-C(Δ170)-F1, -F2, and -F3 vectors were moderately restricted in the nasal turbinates, highly restricted in lungs, and genetically stable in vivo. Among the C(Δ170) vectors, the F1 virus was the most immunogenic and protective against wt RSV challenge. The rHPIV1-L(Y942A) vectors were highly restricted in vivo and were not detectably immunogenic or protective, indicative of overattenuation. The C(Δ170)-F1 construct appears to be suitably attenuated and immunogenic for further development as a bivalent intranasal pediatric vaccine.

IMPORTANCE

There are no vaccines for the pediatric respiratory pathogens RSV and HPIV. We are developing live attenuated RSV and HPIV vaccines for use in virus-naive infants. Live attenuated RSV strains in particular are difficult to develop due to their poor growth and physical instability, but these obstacles could be avoided by the use of a vaccine vector. We describe the development and preclinical evaluation of live attenuated rHPIV1 vectors expressing the RSV F protein. Two different attenuated rHPIV1 backbones were each engineered to express RSV F from three different gene positions. The rHPIV1-C(Δ170)-F1 vector, bearing an attenuating deletion mutation (C(Δ170)) in the P/C gene and expressing RSV F from the pre-N position, was attenuated, stable, and immunogenic against the RSV F protein and HPIV1 in the hamster model and provided substantial protection against RSV challenge. This study provides a candidate rHPIV1-RSV-F vaccine virus suitable for continued development as a bivalent vaccine against two major childhood pathogens.