Illumination of parainfluenza virus infection and transmission in living animals reveals a tissue-specific dichotomy

Immunogenicity and Protective Efficacy of a Single Intranasal Dose Vectored Vaccine Based on Sendai Virus (Moscow Strain) against SARS-CoV-2 Variant of Concern

The mouse paramyxovirus Sendai, which is capable of limited replication in human bronchial epithelial cells without causing disease, is well suited for the development of vector-based intranasal vaccines against respiratory infections, including SARS-CoV-2. Using the Moscow strain of the Sendai virus, we developed a vaccine construct, Sen-Sdelta(M), which expresses the full-length spike (S) protein of the SARS-CoV-2 delta variant. A single intranasal delivery of Sen-Sdelta(M) to Syrian hamsters and BALB/c mice induced high titers of virus-neutralizing antibodies specific to the SARS-CoV-2 delta variant. A significant T-cell response, as determined by IFN-γ ELISpot and ICS methods, was also demonstrated in the mouse model. Mice and hamsters vaccinated with Sen-Sdelta(M) were well protected against SARS-CoV-2 challenge. The viral load in the lungs and nasal turbinates, measured by RT-qPCR and TCID50 assay, decreased dramatically in vaccinated groups. The most prominent effect was revealed in a highly sensitive hamster model, where no tissue samples contained detectable levels of infectious SARS-CoV-2. These results indicate that Sen-Sdelta(M) is a promising candidate as a single-dose intranasal vaccine against SARS-CoV-2, including variants of concern.

Prevention of respiratory virus transmission by resident memory CD8+ T cells

An ideal vaccine both attenuates virus growth and disease in infected individuals and reduces the spread of infections in the population, thereby generating herd immunity. Although this strategy has proved successful by generating humoral immunity to measles, yellow fever and polio, many respiratory viruses evolve to evade pre-existing antibodies1. One approach for improving the breadth of antiviral immunity against escape variants is through the generation of memory T cells in the respiratory tract, which are positioned to respond rapidly to respiratory virus infections2-6. However, it is unknown whether memory T cells alone can effectively surveil the respiratory tract to the extent that they eliminate or greatly reduce viral transmission following exposure of an individual to infection. Here we use a mouse model of natural parainfluenza virus transmission to quantify the extent to which memory CD8+ T cells resident in the respiratory tract can provide herd immunity by reducing both the susceptibility of acquiring infection and the extent of transmission, even in the absence of virus-specific antibodies. We demonstrate that protection by resident memory CD8+ T cells requires the antiviral cytokine interferon-γ (IFNγ) and leads to altered transcriptional programming of epithelial cells within the respiratory tract. These results suggest that tissue-resident CD8+ T cells in the respiratory tract can have important roles in protecting the host against viral disease and limiting viral spread throughout the population.

Vaccine induced memory CD8+ T cells efficiently prevent viral transmission from the respiratory tract

Introduction

Mucosal immunization eliciting local T-cell memory has been suggested for improved protection against respiratory infections caused by viral variants evading pre-existing antibodies. However, it remains unclear whether T-cell targeted vaccines suffice for prevention of viral transmission and to which extent local immunity is important in this context.

Methods

To study the impact of T-cell vaccination on the course of viral respiratory infection and in particular the capacity to inhibit viral transmission, we used a mouse model involving natural murine parainfluenza infection with a luciferase encoding virus and an adenovirus based nucleoprotein targeting vaccine.

Results and discussion

Prior intranasal immunization inducing strong mucosal CD8+ T cell immunity provided an almost immediate shut-down of the incipient infection and completely inhibited contact based viral spreading. If this first line of defense did not operate, as in parentally immunized mice, recirculating T cells participated in accelerated viral control that reduced the intensity of inter-individual transmission. These observations underscore the importance of pursuing the development of mucosal T-cell inducing vaccines for optimal protection of the individual and inhibition of inter-individual transmission (herd immunity), while at the same time explain why induction of a strong systemic T-cell response may still impact viral transmission.

A recombinant murine-like rotavirus with Nano-Luciferase expression reveals tissue tropism, replication dynamics, and virus transmission

Rotaviruses (RVs) are one of the main causes of severe gastroenteritis, diarrhea, and death in children and young animals. While suckling mice prove to be highly useful small animal models of RV infection and pathogenesis, direct visualization tools are lacking to track the temporal dynamics of RV replication and transmissibility in vivo. Here, we report the generation of the first recombinant murine-like RV that encodes a Nano-Luciferase reporter (NLuc) using a newly optimized RV reverse genetics system. The NLuc-expressing RV was replication-competent in cell culture and both infectious and virulent in neonatal mice in vivo. Strong luciferase signals were detected in the proximal and distal small intestines, colon, and mesenteric lymph nodes. We showed, via a noninvasive in vivo imaging system, that RV intestinal replication peaked at days 2 to 5 post infection. Moreover, we successfully tracked RV transmission to uninoculated littermates as early as 3 days post infection, 1 day prior to clinically apparent diarrhea and 3 days prior to detectable fecal RV shedding in the uninoculated littermates. We also observed significantly increased viral replication in Stat1 knockout mice that lack the host interferon signaling. Our results suggest that the NLuc murine-like RV represents a non-lethal powerful tool for the studies of tissue tropism and host and viral factors that regulate RV replication and spread, as well as provides a new tool to facilitate the testing of prophylactic and therapeutic interventions in the future.

Quantifying dose-, strain-, and tissue-specific kinetics of parainfluenza virus infection

Human parainfluenza viruses (HPIVs) are a leading cause of acute respiratory infection hospitalization in children, yet little is known about how dose, strain, tissue tropism, and individual heterogeneity affects the processes driving growth and clearance kinetics. Longitudinal measurements are possible by using reporter Sendai viruses, the murine counterpart of HPIV 1, that express luciferase, where the insertion location yields a wild-type (rSeV-luc(M-F*)) or attenuated (rSeV-luc(P-M)) phenotype. Bioluminescence from individual animals suggests that there is a rapid increase in expression followed by a peak, biphasic clearance, and resolution. However, these kinetics vary between individuals and with dose, strain, and whether the infection was initiated in the upper and/or lower respiratory tract. To quantify the differences, we translated the bioluminescence measurements from the nasopharynx, trachea, and lung into viral loads and used a mathematical model together a nonlinear mixed effects approach to define the mechanisms distinguishing each scenario. The results confirmed a higher rate of virus production with the rSeV-luc(M-F*) virus compared to its attenuated counterpart, and suggested that low doses result in disproportionately fewer infected cells. The analyses indicated faster infectivity and infected cell clearance rates in the lung and that higher viral doses, and concomitantly higher infected cell numbers, resulted in more rapid clearance. This parameter was also highly variable amongst individuals, which was particularly evident during infection in the lung. These critical differences provide important insight into distinct HPIV dynamics, and show how bioluminescence data can be combined with quantitative analyses to dissect host-, virus-, and dose-dependent effects.

Human parainfluenza viruses (HPIVs) cause acute respiratory infections and can lead to the hospitalization of children. HPIV infection severity may vary due to dose, strain, patient, and whether the infection initiates within the upper or lower respiratory tract. There is a need to determine how the rates of virus spread and clearance change in different infection scenarios in order to better understand varying clinical manifestations. The significance of our research is in identifying the dominant mechanisms driving strain-, dose-, and tissue-specific HPIV infection kinetics, and in pairing bioluminescence data with quantitative analyses to determine how the same virus can yield patient-specific outcomes. This work enhances our understanding of HPIV infection and broadens our knowledge viral dynamics in the upper and lower respiratory tracts.

Sendai Virus-Vectored Vaccines That Express Envelope Glycoproteins of Respiratory Viruses

Human respiratory syncytial virus (HRSV), human metapneumovirus (HMPV), and human parainfluenza viruses (HPIVs) are leading causes of respiratory disease in young children, the elderly, and individuals of all ages with immunosuppression. Vaccination strategies against these pneumoviruses and paramyxoviruses are vast in number, yet no licensed vaccines are available. Here, we review development of Sendai virus (SeV), a versatile pediatric vaccine that can (a) serve as a Jennerian vaccine against HPIV1, (b) serve as a recombinant vaccine against HRSV, HPIV2, HPIV3, and HMPV, (c) accommodate foreign genes for viral glycoproteins in multiple intergenic positions, (d) induce durable, mucosal, B-cell, and T-cell immune responses without enhanced immunopathology, (e) protect cotton rats, African green monkeys, and chimpanzees from infection, and (f) be formulated into a vaccine cocktail. Clinical phase I safety trials of SeV have been completed in adults and 3–6-year-old children. Clinical testing of SeVRSV, an HRSV fusion (F) glycoprotein gene recombinant, has also been completed in adults. Positive results from these studies, and collaborative efforts with the National Institutes of Health and the Serum Institute of India assist advanced development of SeV-based vaccines. Prospects are now good for vaccine successes in infants and consequent protection against serious viral disease.

Pathogenicity and transmissibility of a novel respirovirus isolated from a Malayan pangolin

The identification of SARS-CoV-2-like viruses in Malayan pangolins (Manis javanica) has focused attention on these endangered animals and the viruses they carry. We successfully isolated a novel respirovirus from the lungs of a dead Malayan pangolin. Similar to murine respirovirus, the full-length genome of this novel virus was 15 384 nucleotides comprising six genes in the order 3'-(leader)-NP-P-M-F-HN-l-(trailer)-5'. Phylogenetic analysis revealed that this virus belongs to the genus Respirovirus and is most closely related to murine respirovirus. Notably, animal infection experiments indicated that the pangolin virus is highly pathogenic and transmissible in mice, with inoculated mice having variable clinical symptoms and a fatality rate of 70.37 %. The virus was found to replicate in most tissues with the exception of muscle and heart. Contact transmission of the virus was 100 % efficient, although the mice in the contact group displayed milder symptoms, with the virus mainly being detected in the trachea and lungs. The isolation of a novel respirovirus from the Malayan pangolin provides new insight into the evolution and distribution of this important group of viruses and again demonstrates the potential infectious disease threats faced by endangered pangolins.

Primary Swine Respiratory Epithelial Cell Lines for the Efficient Isolation and Propagation of Influenza A Viruses

Influenza virus isolation from clinical samples is critical for the identification and characterization of circulating and emerging viruses. Yet efficient isolation can be difficult. In these studies, we isolated primary swine nasal and tracheal respiratory epithelial cells and immortalized swine nasal epithelial cells (siNEC) and tracheal epithelial cells (siTEC) that retained the abilities to form tight junctions and cilia and to differentiate at the air-liquid interface like primary cells. Critically, both human and swine influenza viruses replicated in the immortalized cells, which generally yielded higher-titer viral isolates from human and swine nasal swabs, supported the replication of isolates that failed to grow in Madin-Darby canine kidney (MDCK) cells, and resulted in fewer dominating mutations during viral passaging than MDCK cells.IMPORTANCE Robust in vitro culture systems for influenza virus are critically needed. MDCK cells, the most widely used cell line for influenza isolation and propagation, do not adequately model the respiratory tract. Therefore, many clinical isolates, both animal and human, are unable to be isolated and characterized, limiting our understanding of currently circulating influenza viruses. We have developed immortalized swine respiratory epithelial cells that retain the ability to differentiate and can support influenza replication and isolation. These cell lines can be used as additional tools to enhance influenza research and vaccine development.

A NanoLuc Luciferase Reporter Pseudorabies Virus for Live Imaging and Quantification of Viral Infection

Pseudorabies (PR), also known as Aujeszky's disease, is an acute infectious disease of pigs, resulting in significant economic losses to the pig industry in many countries. Since 2011, PR outbreaks have occurred in many Bartha-K61-vaccinated pig farms in China. The emerging pseudorabies virus (PRV) variants possess higher pathogenicity in pigs and mice than the strains isolated before. Here, a recombinant PRV (rPRVTJ-NLuc) stably expressing the NanoLuc (NLuc) luciferase fusion with the red fluorescent protein (DsRed) was constructed to trace viral replication and spread in mice. Moreover, both DsRed and NLuc luciferases were stably expressed in the infected cells, and there was no significant difference between wild-type and recombinant viruses in both growth kinetics and pathogenicity. Seven-week-old BALB/c mice were infected with 10³ 50% tissue culture infective dose rPRVTJ-NLuc and subjected to daily imaging. The mice infected with rPRVTJ-NLuc displayed robust bioluminescence that started 4 days postinfection (dpi), bioluminescence signal increased over time, peaked at 5 dpi, remained detectable for at least 6 dpi, and disappeared at 7 dpi, meanwhile, the increased flux accompanied by the spread of the virus from the injection site to the superior respiratory tract. However, the signal was also observed in the spinal cord, trigeminal ganglion, and partial region of the brain from separated tissues, not in living mice. Our results depicted a new approach to rapidly access the replication and pathogenicity of emerging PRVs in mice.

The Challenges of Vaccine Development against Betacoronaviruses: Antibody Dependent Enhancement and Sendai Virus as a Possible Vaccine Vector

To design an effective and safe vaccine against betacoronaviruses, it is necessary to use their evolutionarily conservative antigenic determinants that will elicit the combination of strong humoral and cell-mediated immune responses. Targeting such determinants minimizes the risk of antibody-dependent enhancement of viral infection. This phenomenon was observed in animal trials of experimental vaccines against SARS-CoV-1 and MERS-CoV that were developed based on inactivated coronavirus or vector constructs expressing the spike protein (S) of the virion. The substitution and glycosylation of certain amino acids in the antigenic determinants of the S-protein, as well as its conformational changes, can lead to the same effect in a new experimental vaccine against SARS-CoV-2. Using more conservative structural and accessory viral proteins for the vaccine antigenic determinants will help to avoid this problem. This review outlines approaches for developing vaccines against the new SARS-CoV-2 coronavirus that are based on non-pathogenic viral vectors. For efficient prevention of infections caused by respiratory pathogens the ability of the vaccine to stimulate mucosal immunity in the respiratory tract is important. Such a vaccine can be developed using non-pathogenic Sendai virus vector, since it can be administered intranasally and induce a mucosal immune response that strengthens the antiviral barrier in the respiratory tract and provides reliable protection against infection.

Visualization of chikungunya virus infection in vitro and in vivo

Chikungunya virus (CHIKV), a mosquito-borne alphavirus, has become an important re-emerging pathogen with its rapid spread to many non-endemic areas. The lack of effective vaccines and antiviral agents is largely attributed to the elusive infection and dissemination dynamics in vivo. In this study, we designed and developed a novel, replication-competent, CHIKV reporter virus (CHIKV-iRFP) encoding a near infrared fluorescent protein (iRFP). In vitro and in vivo characterization demonstrated that CHIKV-iRFP retained similar replication and virulence phenotypes to its parental virus. Neonatal BABL/c mice and IFNAR^−/− A129 mice were highly susceptible to CHIKV-iRFP infection. Following intracranial (i.c.) inoculation, CHIKV-iRFP efficiently replicated and disseminated into whole body, resulting in rapid death in an age-dependent manner. Remarkably, upon footpad injection, CHIKV-iRFP readily disseminated from footpad to head and whole skeleton, with a specific tropism for bone marrow. Taken together, this novel reporter virus provides a powerful tool to track real time CHIKV replication and to test the in vivo efficacy of vaccines and antiviral therapeutics.

Development of Stable Rotavirus Reporter Expression Systems

Engineered recombinant viruses expressing reporter genes have been developed for real-time monitoring of replication and for mass screening of antiviral inhibitors. Recently, we reported using a reverse genetics system to develop the first recombinant reporter rotaviruses (RVs) that expressed NanoLuc (NLuc) luciferase. Here, we describe a strategy for developing stable reporter RVs expressing luciferase and green or red fluorescent proteins. The reporter genes were inserted into the open reading frame of NSP1 and expressed as a fusion with an NSP1 peptide consisting of amino acids 1 to 27. The stability of foreign genes within the reporter RV strains harboring a shorter chimeric NSP1-reporter gene was greater than that of those in the original reporter RV strain, independent of the transgene inserted. The improved reporter RV was used to screen for neutralizing monoclonal antibodies (MAbs). Sequence analysis of escape mutants from one MAb clone (clone 29) identified an amino acid substitution (arginine to glycine) at position 441 in the VP4 protein, which resides within neutralizing epitope 5-1 in the VP5* fragment. Furthermore, to express a native reporter protein lacking NSP1 amino acids 1 to 27, the 5'- and 3'-terminal region sequences were modified to restore the predicted secondary RNA structure of the NSP1-reporter chimeric gene. These data demonstrate the utility of reporter RVs for live monitoring of RV infections and also suggest further applications (e.g., RV vaccine vectors, which can induce mucosal immunity against intestinal pathogens).IMPORTANCE Development of reporter RVs has been hampered by the lack of comprehensive reverse genetics systems. Recently, we developed a plasmid-based reverse genetics system that enables generation of reporter RVs expressing NLuc luciferase. The prototype reporter RV had some disadvantages (i.e., the transgene was unstable and was expressed as a fusion protein with a partial NSP1 peptide); however, the improved reporter RV overcomes these problems through modification of the untranslated region of the reporter-NSP1 chimeric gene. This strategy for generating stable reporter RVs could be expanded to diverse transgenes and be used to develop RV transduction vectors. Also, the data improve our understanding of the importance of 5'- and 3'-terminal sequences in terms of genome replication, assembly, and packaging.

Directed Evolution of an Influenza Reporter Virus To Restore Replication and Virulence and Enhance Noninvasive Bioluminescence Imaging in Mice

Reporter viruses provide a powerful tool to study infection, yet incorporating a nonessential gene often results in virus attenuation and genetic instability. Here, we used directed evolution of a luciferase-expressing pandemic H1N1 (pH1N1) 2009 influenza A virus in mice to restore replication kinetics and virulence, increase the bioluminescence signal, and maintain reporter gene expression. An unadapted pH1N1 virus with NanoLuc luciferase inserted into the 5' end of the PA gene segment grew to titers 10-fold less than those of the wild type in MDCK cells and in DBA/2 mice and was less virulent. For 12 rounds, we propagated DBA/2 lung samples with the highest bioluminescence-to-titer ratios. Every three rounds, we compared in vivo replication, weight loss, mortality, and bioluminescence. Mouse-adapted virus after 9 rounds (MA-9) had the highest relative bioluminescence signal and had wild-type-like fitness and virulence in DBA/2 mice. Using reverse genetics, we discovered fitness was restored in virus rPB2-MA9/PA-D479N by a combination of PA-D479N and PB2-E158G amino acid mutations and PB2 noncoding mutations C1161T and C1977T. rPB2-MA9/PA-D479N has increased mRNA transcription, which helps restore wild-type-like phenotypes in DBA/2 and BALB/c mice. Overall, the results demonstrate that directed evolution that maximizes foreign-gene expression while maintaining genetic stability is an effective method to restore wild-type-like in vivo fitness of a reporter virus. Virus rPB2-MA9/PA-D479N is expected to be a useful tool for noninvasive imaging of pH1N1 influenza virus infection and clearance while analyzing virus-host interactions and developing new therapeutics and vaccines.IMPORTANCE Influenza viruses contribute to 290,000 to 650,000 deaths globally each year. Infection is studied in mice to learn how the virus causes sickness and to develop new drugs and vaccines. During experiments, scientists have needed to euthanize groups of mice at different times to measure the amount of infectious virus in mouse tissues. By inserting a foreign gene that causes infected cells to light up, scientists could see infection spread in living mice. Unfortunately, adding an extra gene not needed by the virus slowed it down and made it weaker. Here, we used a new strategy to restore the fitness and lethality of an influenza reporter virus; we adapted it to mouse lungs and selected for variants that had the greatest light signal. The adapted virus can be used to study influenza virus infection, immunology, and disease in living mice. The strategy can also be used to adapt other viruses.

A Simple and Robust Approach for Evaluation of Antivirals Using a Recombinant Influenza Virus Expressing Gaussia Luciferase

Influenza A virus (IAV) causes seasonal epidemics and occasional but devastating pandemics, which are major public health concerns. Because the effectiveness of seasonal vaccines is highly variable and the currently available drugs are limited in their efficacy because of the emergence of drug resistance, there is an urgent need to develop novel antivirals. In this study, we characterized a recombinant IAV-carrying Gaussia luciferase (Gluc) gene and determined its potential as a tool for evaluating therapeutics. We demonstrated that this recombinant IAV is replication-competent in tissue culture and pathogenic in mice, although it is slightly attenuated compared to the parental virus. Luciferase expression correlated well with virus propagation both in vitro and in vivo, providing a simple measure for viral replication in tissue culture and in mouse lungs. To demonstrate the utility of this virus, ribavirin and oseltamivir phosphate were used to treat the IAV-infected cells and mice, and we observed the dose-dependent inhibition of viral replication by a luciferase assay. Moreover, the decreased luciferase expression in the infected lungs could predict the protective efficacy of antiviral interventions as early as day 2 post virus challenge. In summary, this study provides a new and quantitative approach to evaluate antivirals against IAV.

Clinical and Molecular Epidemiology of Human Parainfluenza Viruses 1-4 in Children from Viet Nam

HPIVs are serologically and genetically grouped into four species that account for up to 10% of all hospitalizations due to acute respiratory infection in children under the age of five. Genetic and epidemiological data for the four HPIVs derived from two pediatric cohorts in Viet Nam are presented. Respiratory samples were screened for HPIV1-4 by real-time PCR. Demographic and clinical data of patients infected with different HPIV were compared. We used a hemi-nested PCR approach to generate viral genome sequences from HPIV-positive samples and conducted a comprehensive phylogenetic analysis. In total, 170 samples tested positive for HPIV. HPIV3 was most commonly detected in our cohort and 80 co-detections of HPIV with other respiratory viruses were found. Phylogenetic analyses suggest local endemic circulation as well as punctuated introductions of new HPIV lineages. Viral gene flow analysis revealed that Viet Nam is a net importer of viral genetic diversity. Epidemiological analyses imply similar disease severity for all HPIV species. HPIV sequences from Viet Nam formed local clusters and were interspersed with sequences from diverse geographic regions. Combined, this new knowledge will help to investigate global HPIV circulation patterns in more detail and ultimately define more suitable vaccine strains.

Development of a reverse genetics system for Sosuga virus allows rapid screening of antiviral compounds

Sosuga virus (SOSV) is a recently discovered zoonotic paramyxovirus isolated from a single human case in 2012; it has been ecologically and epidemiologically associated with transmission by the Egyptian rousette bat (Rousettus aegyptiacus). Bats have long been recognized as sources of novel zoonotic pathogens, including highly lethal paramyxoviruses like Nipah virus (NiV) and Hendra virus (HeV). The ability of SOSV to cause severe human disease supports the need for studies on SOSV pathogenesis to better understand the potential impact of this virus and to identify effective treatments. Here we describe a reverse genetics system for SOSV comprising a minigenome-based assay and a replication-competent infectious recombinant reporter SOSV that expresses the fluorescent protein ZsGreen1 in infected cells. First, we used the minigenome assay to rapidly screen for compounds inhibiting SOSV replication at biosafety level 2 (BSL-2). The antiviral activity of candidate compounds was then tested against authentic viral replication using the reporter SOSV at BSL-3. We identified several compounds with anti-SOSV activity, several of which also inhibit NiV and HeV. Alongside its utility in screening for potential SOSV therapeutics, the reverse genetics system described here is a powerful tool for analyzing mechanisms of SOSV pathogenesis, which will facilitate our understanding of how to combat the potential public health threats posed by emerging bat-borne paramyxoviruses.

Dynamics of Sendai Virus Spread, Clearance, and Immunotherapeutic Efficacy after Hematopoietic Cell Transplant Imaged Noninvasively in Mice

There are no approved vaccines or virus-specific treatments for human parainfluenza viruses (HPIVs), which have recently been reclassified into the species Human respirovirus 1, Human respirovirus 3, Human rubulavirus 2, and Human rubulavirus 4 These viruses cause morbidity and mortality in immunocompromised patients, including those undergoing hematopoietic cell transplant (HCT). No small-animal models for noninvasive imaging of respiratory virus infection in the HCT host exist, despite the utility that such a system would offer to monitor prolonged infection, its clearance, and treatment options. We used a luciferase-expressing reporter virus to noninvasively image in mice the infection of murine respirovirus (strain Sendai virus [SeV]), the murine counterpart of HPIV1. Independent of disease severity, the clearance of infection began approximately 21 days after HCT, largely due to the recovery of CD8+ T cells. Immunotherapy with granulocyte colony-stimulating factor (G-CSF) and adoptive transfer of natural killer (NK) cells provided a limited therapeutic benefit. Treatment with a fusion (F) protein-specific monoclonal antibody arrested the spread of lung infection and reduced the disease severity even when treatment was delayed to up to 10 days postinfection but had little observable effect on upper respiratory tract infection. Adoptive transfer of virus-specific T cells at 10 days postinfection accelerated the clearance by 5 days, reduced the extent of infection throughout the respiratory tract, and reduced the disease severity. Overall, the results support investigation of the clinical treatment of respiratory virus infection in the HCT host with monoclonal antibodies and adoptive T-cell transfer; the imaging system should be extendable to other respiratory viruses, such as respiratory syncytial virus and influenza virus.IMPORTANCE Parainfluenza viruses are a major cause of disease and death due to respiratory virus infection in the immunocompromised host, including those undergoing bone marrow transplantation. There are currently no effective treatment measures. We noninvasively imaged mice that were undergoing a bone marrow transplant and infected with Sendai virus, a murine parainfluenza virus (respirovirus). For the first time, we show the therapeutic windows of adoptive T-cell therapy and treatment with a monoclonal antibody to the fusion (F) protein in clearing Sendai virus from the respiratory tract and reducing disease severity. Mice tolerated these treatments without any detectable toxicity. These findings pave the way for studies assessing the safety of T-cell therapy against parainfluenza virus in humans. Adoptive T-cell therapy against other blood-borne viruses in humans has been shown to be safe and effective. Our model of noninvasive imaging in mice that had undergone a bone marrow transplant may be well suited to track other respiratory virus infections and develop novel preventive and therapeutic strategies.

Delineating morbillivirus entry, dissemination and airborne transmission by studying in vivo competition of multicolor canine distemper viruses in ferrets

Identification of cellular receptors and characterization of viral tropism in animal models have vastly improved our understanding of morbillivirus pathogenesis. However, specific aspects of viral entry, dissemination and transmission remain difficult to recapitulate in animal models. Here, we used three virologically identical but phenotypically distinct recombinant (r) canine distemper viruses (CDV) expressing different fluorescent reporter proteins for in vivo competition and airborne transmission studies in ferrets (Mustela putorius furo). Six donor ferrets simultaneously received three rCDVs expressing green, red or blue fluorescent proteins via conjunctival (ocular, Oc), intra-nasal (IN) or intra-tracheal (IT) inoculation. Two days post-inoculation sentinel ferrets were placed in physically separated adjacent cages to assess airborne transmission. All donor ferrets developed lymphopenia, fever and lethargy, showed progressively increasing systemic viral loads and were euthanized 14 to 16 days post-inoculation. Systemic replication of virus inoculated via the Oc, IN and IT routes was detected in 2/6, 5/6 and 6/6 ferrets, respectively. In five donor ferrets the IT delivered virus dominated, although replication of two or three different viruses was detected in 5/6 animals. Single lymphocytes expressing multiple fluorescent proteins were abundant in peripheral blood and lymphoid tissues, demonstrating the occurrence of double and triple virus infections. Transmission occurred efficiently and all recipient ferrets showed evidence of infection between 18 and 22 days post-inoculation of the donor ferrets. In all cases, airborne transmission resulted in replication of a single-colored virus, which was the dominant virus in the donor ferret. This study demonstrates that morbilliviruses can use multiple entry routes in parallel, and co-infection of cells during viral dissemination in the host is common. Airborne transmission was efficient, although transmission of viruses expressing a single color suggested a bottleneck event. The identity of the transmitted virus was not determined by the site of inoculation but by the viral dominance during dissemination.

Zoonotic Potential of Emerging Paramyxoviruses: Knowns and Unknowns

The risk of spillover of enzootic paramyxoviruses and the susceptibility of recipient human and domestic animal populations are defined by a broad collection of ecological and molecular factors that interact in ways that are not yet fully understood. Nipah and Hendra viruses were the first highly lethal zoonotic paramyxoviruses discovered in modern times, but other paramyxoviruses from multiple genera are present in bats and other reservoirs that have unknown potential to spillover into humans. We outline our current understanding of paramyxovirus reservoir hosts and the ecological factors that may drive spillover, and we explore the molecular barriers to spillover that emergent paramyxoviruses may encounter. By outlining what is known about enzootic paramyxovirus receptor usage, mechanisms of innate immune evasion, and other host-specific interactions, we highlight the breadth of unexplored avenues that may be important in understanding paramyxovirus emergence.

Luciferase-tagged wild-type and tropism-deficient mouse cytomegaloviruses reveal early dynamics of host colonization following peripheral challenge

Cytomegaloviruses (CMVs) establish persistent, systemic infections and cause disease by maternal-foetal transfer, suggesting that their dissemination is a key target for antiviral intervention. Late clinical presentation has meant that human CMV (HCMV) dissemination is not well understood. Murine CMV (MCMV) provides a tractable model. Whole mouse imaging of virus-expressed luciferase has proved a useful way to track systemic infections. MCMV, in which the abundant lytic gene M78 was luciferase-tagged via a self-cleaving peptide (M78-LUC), allowed serial, unbiased imaging of systemic and peripheral infection without significant virus attenuation. Ex vivo luciferase imaging showed greater sensitivity than plaque assay, and revealed both well-known infection sites (the lungs, lymph nodes, salivary glands, liver, spleen and pancreas) and less explored sites (the bone marrow and upper respiratory tract). We applied luciferase imaging to tracking MCMV lacking M33, a chemokine receptor conserved in HCMV and a proposed anti-viral drug target. M33-deficient M78-LUC colonized normally in peripheral sites and local draining lymph nodes but spread poorly to the salivary gland, suggesting a defect in vascular transport consistent with properties of a chemokine receptor.

Non-invasive Imaging of Sendai Virus Infection in Pharmacologically Immunocompromised Mice: NK and T Cells, but not Neutrophils, Promote Viral Clearance after Therapy with Cyclophosphamide and Dexamethasone

In immunocompromised patients, parainfluenza virus (PIV) infections have an increased potential to spread to the lower respiratory tract (LRT), resulting in increased morbidity and mortality. Understanding the immunologic defects that facilitate viral spread to the LRT will help in developing better management protocols. In this study, we immunosuppressed mice with dexamethasone and/or cyclophosphamide then monitored the spread of viral infection into the LRT by using a noninvasive bioluminescence imaging system and a reporter Sendai virus (murine PIV type 1). Our results show that immunosuppression led to delayed viral clearance and increased viral loads in the lungs. After cessation of cyclophosphamide treatment, viral clearance occurred before the generation of Sendai-specific antibody responses and coincided with rebounds in neutrophils, T lymphocytes, and natural killer (NK) cells. Neutrophil suppression using anti-Ly6G antibody had no effect on infection clearance, NK-cell suppression using anti-NK antibody delayed clearance, and T-cell suppression using anti-CD3 antibody resulted in no clearance (chronic infection). Therapeutic use of hematopoietic growth factors G-CSF and GM-CSF had no effect on clearance of infection. In contrast, treatment with Sendai virus-specific polysera or a monoclonal antibody limited viral spread into the lungs and accelerated clearance. Overall, noninvasive bioluminescence was shown to be a useful tool to study respiratory viral progression, revealing roles for NK and T cells, but not neutrophils, in Sendai virus clearance after treatment with dexamethasone and cyclophosphamide. Virus-specific antibodies appear to have therapeutic potential.

Fluorescent and Bioluminescent Reporter Myxoviruses

The advent of virus reverse genetics has enabled the incorporation of genetically encoded reporter proteins into replication-competent viruses. These reporters include fluorescent proteins which have intrinsic chromophores that absorb light and re-emit it at lower wavelengths, and bioluminescent proteins which are luciferase enzymes that react with substrates to produce visible light. The incorporation of these reporters into replication-competent viruses has revolutionized our understanding of molecular virology and aspects of viral tropism and transmission. Reporter viruses have also enabled the development of high-throughput assays to screen antiviral compounds and antibodies and to perform neutralization assays. However, there remain technical challenges with the design of replication-competent reporter viruses, and each reporter has unique advantages and disadvantages for specific applications. This review describes currently available reporters, design strategies for incorporating reporters into replication-competent paramyxoviruses and orthomyxoviruses, and the variety of applications for which these tools can be utilized both in vitro and in vivo.

The Emerging Duck Flavivirus Is Not Pathogenic for Primates and Is Highly Sensitive to Mammalian Interferon Antiviral Signaling

Flaviviruses pose a significant threat to both animals and humans. Recently, a novel flavivirus, duck Tembusu virus (DTMUV), was identified to be the causative agent of a serious duck viral disease in Asia. Its rapid spread, expanding host range, and uncertain transmission routes have raised substantial concerns regarding its potential threats to nonavian hosts, including humans. Here, we demonstrate that DTMUV is not pathogenic for nonhuman primates and is highly sensitive to mammal type I interferon (IFN) signaling. In vitro assays demonstrated that DTMUV infected and replicated efficiently in various mammalian cell lines. Further tests in mice demonstrated high neurovirulence and the age-dependent neuroinvasiveness of the virus. In particular, the inoculation of DTMUV into rhesus monkeys did not result in either viremia or apparent clinical symptoms, although DTMUV-specific humoral immune responses were detected. Furthermore, we revealed that although avian IFN failed to inhibit DTMUV in avian cells, DTMUV was more sensitive to the antiviral effects of type I interferon than other known human-pathogenic flaviviruses. Knockout of the type I IFN receptor in mice caused apparent viremia, viscerotropic disease, and mortality, indicating a vital role of IFN signaling in protection against DTMUV infection. Collectively, we provide direct experimental evidence that this novel avian-origin DTMUV possesses a limited capability to establish infection in immunocompetent primates due to its decreased antagonistic activity in the mammal IFN system. Furthermore, our findings highlight the potential risk of DTMUV infection in immunocompromised individuals and warrant studies on the cross-species transmission and pathogenesis of this novel flavivirus.

IMPORTANCE

Mosquito-borne flaviviruses comprise a large group of pathogenic and nonpathogenic members. The pathogenic flaviviruses include dengue, West Nile, and Japanese encephalitis viruses, and the nonpathogenic flaviviruses normally persist in a natural cycle and rarely cause disease in humans. A novel flavivirus, DTMUV (also known as duck egg drop syndrome flavivirus [DEDSV]) was identified in 2012 in ducks and then rapidly spread to several Asian countries. This new flavivirus was then shown to infect multiple avian species, resulting in neurological symptoms with unknown routes of transmission. There is public concern regarding its potential transmission from birds to humans and other nonavian hosts. Our present study shows that the mammalian IFN system can efficiently eliminate DTMUV infection and that the emergence of severe DTMUV-associated disease in mammals, especially humans, is unlikely. Currently, DTMUV infection mostly affects avian species.

Sendai virus as a backbone for vaccines against RSV and other human paramyxoviruses

Human paramyxoviruses are the etiological agents for life-threatening respiratory virus infections of infants and young children. These viruses, including respiratory syncytial virus (RSV), the human parainfluenza viruses (hPIV1-4) and human metapneumovirus (hMPV), are responsible for millions of serious lower respiratory tract infections each year worldwide. There are currently no standard treatments and no licensed vaccines for any of these pathogens. Here we review research with which Sendai virus, a mouse parainfluenza virus type 1, is being advanced as a Jennerian vaccine for hPIV1 and as a backbone for RSV, hMPV and other hPIV vaccines for children.

TRIM32 Senses and Restricts Influenza A Virus by Ubiquitination of PB1 Polymerase

Polymerase basic protein 1 (PB1) is the catalytic core of the influenza A virus (IAV) RNA polymerase complex essential for viral transcription and replication. Understanding the intrinsic mechanisms which block PB1 function could stimulate development of new anti-influenza therapeutics. Affinity purification coupled with mass spectrometry (AP-MS) was used to identify host factors interacting with PB1. Among PB1 interactors, the E3 ubiquitin ligase TRIM32 interacts with PB1 proteins derived from multiple IAV strains. TRIM32 senses IAV infection by interacting with PB1 and translocates with PB1 to the nucleus following influenza infection. Ectopic TRIM32 expression attenuates IAV infection. Conversely, RNAi depletion and knockout of TRIM32 increase susceptibility of tracheal and lung epithelial cells to IAV infection. Reconstitution of trim32^-/- mouse embryonic fibroblasts with TRIM32, but not a catalytically inactive mutant, restores viral restriction. Furthermore, TRIM32 directly ubiquitinates PB1, leading to PB1 protein degradation and subsequent reduction of polymerase activity. Thus, TRIM32 is an intrinsic IAV restriction factor which senses and targets the PB1 polymerase for ubiquitination and protein degradation. TRIM32 represents a model of intrinsic immunity, in which a host protein directly senses and counters viral infection in a species specific fashion by directly limiting viral replication.

Influenza A virus presents a continued threat to global health with considerable economic and social impact. Vaccinations against influenza are not always effective, and many influenza strains have developed resistance to current antiviral drugs. Thus, it is imperative to find new strategies for the prevention and treatment of influenza. Influenza RNA-dependent RNA polymerase is a multifunctional protein essential for both transcription and replication of the viral genome. However, we have little understanding of the mechanisms regulating viral RNA polymerase activity or the innate cellular defenses against this critical viral enzyme. We describe how the E3 ubiquitin ligase, TRIM32, inhibits the activity of the influenza RNA polymerase and defends respiratory epithelial cells against infection with influenza A viruses. TRIM32 directly senses the PB1 subunit of the influenza virus RNA polymerase complex and targets it for ubiquitination and proteasomal degradation, thereby reducing viral polymerase activity.

Visualizing real-time influenza virus infection, transmission and protection in ferrets

Influenza transmission efficiency in ferrets is vital for risk-assessment studies. However, the inability to monitor viral infection and transmission dynamics in real time only provides a glimpse into transmissibility. Here we exploit a replication-competent influenza reporter virus to investigate dynamics of infection/transmission in ferrets. Bioluminescent imaging of ferrets infected with A/California/04/2009 H1N1 virus (CA/09) encoding NanoLuc (NLuc) luciferase provides the first real-time snapshot of influenza infection/transmission. Luminescence in the respiratory tract and in less well-characterized extra-pulmonary sites is observed, and imaging identifies infections in animals that would have otherwise been missed by traditional methods. Finally, the reporter virus significantly increases the speed and sensitivity of virological and serological assays. Thus, bioluminescent imaging of influenza infections rapidly determines intra-host dissemination, inter-host transmission and viral load, revealing infection dynamics and pandemic potential of the virus. These results have important implications for antiviral drug susceptibility, vaccine efficacy, transmissibility and pathogenicity studies.

Ferrets are the main animal model used for research on influenza transmission. Here, the authors investigate the dynamics of infection and transmission in ferrets using a replication-competent influenza reporter virus and real-time bioluminescence imaging.

Relationships among dissemination of primary parainfluenza virus infection in the respiratory tract, mucosal and peripheral immune responses, and protection from reinfection: a noninvasive bioluminescence-imaging study

Respiratory paramyxoviruses such as respiratory syncytial virus (RSV) and human parainfluenza virus type 1 (HPIV1) to HPIV4 infect virtually all children by the age of 2 to 5 years, leading to partial but incomplete protection from reinfection. Here, we used luciferase-expressing reporter Sendai viruses (the murine counterpart of HPIV1) to noninvasively measure primary infection, immune responses, and protection from reinfection by either a lethal challenge or natural transmission in living mice. Both nonattenuated and attenuated reporter Sendai viruses were used, and three inoculation strategies were employed: intramuscular (i.m.), intranasal (i.n.) at a low dose and low volume, and i.n. at a high dose and high volume. High-dose, high-volume i.n. inoculation resulted in the highest levels of antibody responses and protection from reinfection. Low-dose, low-volume i.n. inoculation afforded complete protection from contact transmission and protection from morbidity, mortality, and viral growth during lethal challenge. i.m. inoculation was inferior to i.n. inoculation at inducing antibody responses and protection from challenge. For individual mice and across groups, the levels of serum binding and neutralizing antibody responses correlated with primary infection and protection from reinfection in the lungs. Contact transmission, the predominant mode of parainfluenza virus transmission, was modeled accurately by direct i.n. inoculation of Sendai virus at a low dose and low volume and was completely preventable by i.n. vaccination of an attenuated virus at a low dose and low volume. The data highlight differences in infection and protection from challenge in the upper versus lower respiratory tract and bear upon live attenuated vaccine development.

IMPORTANCE

There are currently no licensed vaccines against HPIVs and human RSV (HRSV), important respiratory pathogens of infants and children. Natural infection leads to partial but incomplete protective immunity, resulting in subsequent reinfections even in the absence of antigenic drift. Here, we used noninvasive bioluminescence imaging in a mouse model to dissect relationships among (i) the mode of inoculation, (ii) the dynamics of primary infection, (iii) consequent immune responses, and (iv) protection from high-dose, high-volume lethal challenge and contact transmission, which we find here to be similar to that of a mild low-dose, low-volume upper respiratory tract (URT)-biased infection. Our studies demonstrate the superiority of i.n. versus i.m. vaccination in protection against both lethal challenge and contact transmission. In addition to providing correlates of protection that will assist respiratory virus vaccine development, these studies extend the development of an increasingly used technique for the study of viral infection and immunity, noninvasive bioluminescence imaging.

Visualizing the replication of respiratory syncytial virus in cells and in living mice

Respiratory syncytial virus (RSV) is the most important cause of severe lower-respiratory tract disease in calves and young children, yet no human vaccine nor efficient curative treatments are available. Here we describe a recombinant human RSV reverse genetics system in which the red fluorescent protein (mCherry) or the firefly luciferase (Luc) genes are inserted into the RSV genome. Expression of mCherry and Luc are correlated with infection rate, allowing the monitoring of RSV multiplication in cell culture. Replication of the Luc-encoding virus in living mice can be visualized by bioluminescent imaging, bioluminescence being detected in the snout and lungs of infected mice after nasal inoculation. We propose that these recombinant viruses are convenient and valuable tools for screening of compounds active against RSV, and can be used as an extremely sensitive readout for studying effects of antiviral therapeutics in living mice.

A novel reporter system for neutralizing and enhancing antibody assay against dengue virus

Background

Dengue virus (DENV) still poses a global public health threat, and no vaccine or antiviral therapy is currently available. Antibody plays distinct roles in controlling DENV infections. Neutralizing antibody is protective against DENV infection, whereas sub-neutralizing concentration of antibody can increase DENV infection, termed antibody-dependent enhancement (ADE). Plaque-based assay represents the most widely accepted method measuring neutralizing or enhancing antibodies.

Results

In this study, a novel reporter virus-based system was developed for measuring neutralization and ADE activity. A stable Renilla luciferase reporter DENV (Luc-DENV) that can produce robust luciferase signals in BHK-21 and K562 cells were used to establish the assay and validated against traditional plaque-based assay. Luciferase value analysis using various known DENV-specific monoclonal antibodies showed good repeatability and a well linear correlation with conventional plaque-based assays. The newly developed assay was finally validated with clinical samples from infected animals and individuals.

Conclusions

This reporter virus-based assay for neutralizing and enhancing antibody evaluation is rapid, lower cost, and high throughput, and will be helpful for laboratory detection and epidemiological investigation for DENV antibodies.

Chimeric bovine/human parainfluenza virus type 3 expressing respiratory syncytial virus (RSV) F glycoprotein: effect of insert position on expression, replication, immunogenicity, stability, and protection against RSV infection

A recombinant chimeric bovine/human parainfluenza type 3 virus (rB/HPIV3) vector expressing the respiratory syncytial virus (RSV) fusion F glycoprotein previously exhibited disappointing levels of RSV F immunogenicity and genetic stability in children (D. Bernstein et al., Pediatr. Infect. Dis. J. 31:109-114, 2012; C.-F. Yang et al., Vaccine 31:2822-2827, 2013). To investigate parameters that might affect vaccine performance and stability, we constructed and characterized rB/HPIV3 viruses expressing RSV F from the first (pre-N), second (N-P), third (P-M), and sixth (HN-L) genome positions. There was a 30- to 69-fold gradient in RSV F expression from the first to the sixth position. The inserts moderately attenuated vector replication in vitro and in the upper and lower respiratory tracts of hamsters: this was not influenced by the level of RSV F expression and syncytium formation. Surprisingly, inserts in the second, third, and sixth positions conferred increased temperature sensitivity: this was greatest for the third position and was the most attenuating in vivo. Each rB/HPIV3 vector induced a high titer of neutralizing antibodies in hamsters against RSV and HPIV3. Protection against RSV challenge was greater for position 2 than for position 6. Evaluation of insert stability suggested that RSV F is under selective pressure to be silenced during vector replication in vivo, but this was not exacerbated by a high level of RSV F expression and generally involved a small percentage of recovered vector. Vector passaged in vitro accumulated mutations in the HN open reading frame, causing a dramatic increase in plaque size that may have implications for vaccine production and immunogenicity.

IMPORTANCE

The research findings presented here will be instrumental for improving the design of a bivalent pediatric vaccine for respiratory syncytial virus and parainfluenza virus type 3, two major causes of severe respiratory tract infection in infants and young children. Moreover, this knowledge has general application to the development and clinical evaluation of other mononegavirus vectors and vaccines.

Development and application of reporter-expressing mononegaviruses: current challenges and perspectives

Reverse genetics allows the generation of recombinant viruses entirely from cDNA. One application of this technology is the creation of reporter-expressing viruses, which greatly increase the detail and ease with which these viruses can be studied. However, there are a number of challenges when working with reporter-expressing viruses. Both the reporter protein itself as well as the genetic manipulations within the viral genome required for expression of this reporter can result in altered biological properties of the recombinant virus, and lead to attenuation in vitro and/or in vivo. Further, instability of reporter expression and purging of the genetic information encoding for the reporter from the viral genome can be an issue. Finally, a practical challenge for in vivo studies lies in the attenuation of light signals when traversing tissues. Novel expression strategies and the continued development of brighter, red and far-red shifted reporters and the increased use of bioluminescent reporters for in vivo applications promise to overcome some of these limitations in future. However, a "one size fits all" approach to the design of reporter-expressing viruses has thus far not been possible. Rather, a reporter suited to the intended application must be selected and an appropriate expression strategy and location for the reporter in the viral genome chosen. Still, attenuating effects of the reporter on viral fitness are difficult to predict and have to be carefully assessed with respect to the intended application. Despite these limitations the generation of suitable reporter-expressing viruses will become more common as technology and our understanding of the intricacies of viral gene expression and regulation improves, allowing deeper insight into virus biology both in living cells and in animals.

Highly sensitive real-time in vivo imaging of an influenza reporter virus reveals dynamics of replication and spread

The continual public health threat posed by the emergence of novel influenza viruses necessitates the ability to rapidly monitor infection and spread in experimental systems. To analyze real-time infection dynamics, we have created a replication-competent influenza reporter virus suitable for in vivo imaging. The reporter virus encodes the small and bright NanoLuc luciferase whose activity serves as an extremely sensitive readout of viral infection. This virus stably maintains the reporter construct and replicates in culture and in mice with near-native properties. Bioluminescent imaging of the reporter virus permits serial observations of viral load and dissemination in infected animals, even following clearance of a sublethal challenge. We further show that the reporter virus recapitulates known restrictions due to host range and antiviral treatment, suggesting that this technology can be applied to studying emerging influenza viruses and the impact of antiviral interventions on infections in vivo. These results describe a generalizable method to quickly determine the replication and pathogenicity potential of diverse influenza strains in animals.

Mode of parainfluenza virus transmission determines the dynamics of primary infection and protection from reinfection

Little is known about how the mode of respiratory virus transmission determines the dynamics of primary infection and protection from reinfection. Using non-invasive imaging of murine parainfluenza virus 1 (Sendai virus) in living mice, we determined the frequency, timing, dynamics, and virulence of primary infection after contact and airborne transmission, as well as the tropism and magnitude of reinfection after subsequent challenge. Contact transmission of Sendai virus was 100% efficient, phenotypically uniform, initiated and grew to robust levels in the upper respiratory tract (URT), later spread to the lungs, grew to a lower level in the lungs than the URT, and protected from reinfection completely in the URT yet only partially in the lungs. Airborne transmission through 7.6-cm and 15.2-cm separations between donor and recipient mice was 86%-100% efficient. The dynamics of primary infection after airborne transmission varied between individual mice and included the following categories: (a) non-productive transmission, (b) tracheal dominant, (c) tracheal initiated yet respiratory disseminated, and (d) nasopharyngeal initiated yet respiratory disseminated. Any previous exposure to Sendai virus infection protected from mortality and severe morbidity after lethal challenge. Furthermore, a higher level of primary infection in a given respiratory tissue (nasopharynx, trachea, or lungs) was inversely correlated with the level of reinfection in that same tissue. Overall, the mode of transmission determined the dynamics and tropism of primary infection, which in turn governed the level of seroconversion and protection from reinfection. These data are the first description of the dynamics of respiratory virus infection and protection from reinfection throughout the respiratory tracts of living animals after airborne transmission. This work provides a basis for understanding parainfluenza virus transmission and protective immunity and for developing novel vaccines and non-pharmaceutical interventions.

Anticipatory nausea and vomiting due to chemotherapy

As a specific variation of chemotherapy-induced nausea and vomiting, anticipatory nausea and vomiting (ANV) appears particularly linked to psychological processes. The three predominant factors related to ANV are classical conditioning; demographic and treatment-related factors; and anxiety or negative expectancies. Laboratory models have provided some support for these underlying mechanisms for ANV. ANV may be treated with medical or pharmacological interventions, including benzodiazepines and other psychotropic medications. However, behavioral treatments, including systematic desensitization, remain first line options for addressing ANV. Some complementary treatment approaches have shown promise in reducing ANV symptoms. Additional research into these approaches is needed. This review will address the underlying models of ANV and provide a discussion of these various treatment options.

Inhibition of primary clinical isolates of human parainfluenza virus by DAS181 in cell culture and in a cotton rat model

DAS181 is a novel drug in development for the treatment of influenza as well as human parainfluenza viruses (hPIVs). Previous studies demonstrated that DAS181 inhibited laboratory strains of hPIV, but no tests were conducted with primary clinical isolates of hPIV. To fill this gap, we studied six primary isolates including hPIV-2 and hPIV-3. First tests showed that the amplification of all viruses in vitro was reproducibly inhibited with DAS181 drug concentrations ranging between 0.1 and 1nM. An hPIV-3 primary clinical isolate was then tested in a cotton rat model for sensitivity to 0.3-1mg/kg drug treatments. Results showed that virus amplification in the lower respiratory tract was significantly and reproducibly inhibited by drug. Together, experiments demonstrated that DAS181 inhibited primary clinical isolates of hPIV in vitro and in vivo at doses similar to those previously described for inhibition of laboratory hPIV and influenza virus isolates.

Current pharmacotherapy for chemotherapy-induced nausea and vomiting in cancer patients

INTRODUCTION

Nausea and vomiting are two of the most frequent and troubling side effects patients experience during chemotherapy, interfering with compliance with cancer therapies and quality of life. While newly available treatments have improved our ability to manage nausea and vomiting, anticipatory and delayed nausea and vomiting are still major problems for patients receiving chemotherapy. Many cancer patients consider delaying future chemotherapy cycles and some contemplate stopping chemotherapy altogether because of their fear of experiencing further nausea and vomiting.

AREAS COVERED

The purpose of this article is to provide an overview of the pathopsychophysiology of chemotherapy-induced nausea and vomiting (CINV), the recommended guidelines for treatment, and current agents in late-stage clinical trials, and future research needs to address the continued challenges of treatment-related nausea and vomiting.

EXPERT OPINION

Despite advances in pharmaceutical and behavioral therapies, and the provision of standard clinical guidelines for effectively managing CINV, patients continue to experience it. Moreover, control of nausea, acute and delayed, and anticipatory nausea and vomiting remains an important, unmet need among cancer patients. It is critical to focus attention on better understanding the mechanisms underlying nausea, anticipatory symptoms and delayed symptoms.

In vivo bioluminescent imaging of influenza a virus infection and characterization of novel cross-protective monoclonal antibodies

Influenza A virus is a major human pathogen responsible for seasonal epidemics as well as pandemic outbreaks. Due to the continuing burden on human health, the need for new tools to study influenza virus pathogenesis as well as to evaluate new therapeutics is paramount. We report the development of a stable, replication-competent luciferase reporter influenza A virus that can be used for in vivo imaging of viral replication. This imaging is noninvasive and allows for the longitudinal monitoring of infection in living animals. We used this tool to characterize novel monoclonal antibodies that bind the conserved stalk domain of the viral hemagglutinin of H1 and H5 subtypes and protect mice from lethal disease. The use of luciferase reporter influenza viruses allows for new mechanistic studies to expand our knowledge of virus-induced disease and provides a new quantitative method to evaluate future antiviral therapies.

Influence of antigen insertion site and vector dose on immunogenicity and protective capacity in Sendai virus-based human parainfluenza virus type 3 vaccines

Recombinant Sendai virus (rSeV) was used as a live, attenuated vaccine vector for intranasal inoculation and mucosal expression of the hemagglutinin-neuraminidase (HN) surface glycoprotein of human parainfluenza virus type 3 (HPIV3). Two vaccine candidates rSeV-HPIV3HN(P-M) and rSeV-HPIV3(F-HN) were constructed in which the HPIV3 HN open reading frame and an additional gene junction was inserted in the P-M and F-HN gene junctions of rSeV, respectively. The rSeV-HPIV3HN(P-M) virus was attenuated compared to rSeV-HPIV3(F-HN) in LLC-MK2 cells, and yet both vaccine candidates grew to similar extents in NHBE cells and in the respiratory tracts of cotton rats. These results suggest that in vitro vector growth in NHBE cells more accurately predicts virus yield in cotton rats than does growth in LLC-MK2 cells. Both vaccine vectors elicited high levels of serum neutralizing antibodies and conferred protection from HPIV3 challenge in cotton rats. Compared to vaccination with a high dose (2,000,000 PFU), intranasal inoculation with a low dose (200 PFU) resulted in a 10-fold decrease in vector growth in the nasal cavity and trachea and a 50-fold decrease in the lungs. However, low-dose vaccination resulted in only modest decreases in anti-HPIV3 antibodies in sera and was sufficient to confer complete protection from HPIV3 challenge. Varying the HPIV3 antigen insertion site and vector dose allowed fine-tuning of the in vivo growth and immunogenicity of rSeV-based vaccines, but all four vaccination strategies tested resulted in complete protection from HPIV3 challenge. These results highlight the versatility of the rSeV platform for developing intranasally administered respiratory virus vaccines.

Measles virus infection of epithelial cells in the macaque upper respiratory tract is mediated by subepithelial immune cells

Measles virus (MV), one of the most contagious viruses infecting humans, causes a systemic infection leading to fever, immune suppression, and a characteristic maculopapular rash. However, the specific mechanism or mechanisms responsible for the spread of MV into the respiratory epithelium in the late stages of the disease are unknown. Here we show the crucial role of PVRL4 in mediating the spread of MV from immune to epithelial cells by generating a PVRL4 "blind" recombinant wild-type MV and developing a novel in vitro coculture model of B cells with primary differentiated normal human bronchial epithelial cells. We utilized the macaque model of measles to analyze virus distribution in the respiratory tract prior to and at the peak of MV replication. Expression of PVRL4 was widespread in both the lower and upper respiratory tract (URT) of macaques, indicating MV transmission can be facilitated by more than only epithelial cells of the trachea. Analysis of tissues collected at early time points after experimental MV infection demonstrated the presence of MV-infected lymphoid and myeloid cells contacting respiratory tract epithelium in the absence of infected epithelial cells, suggesting that these immune cells seed the infection in vivo. Thereafter, lateral cell-to-cell spread of MV led to the formation of large foci of infected cells in the trachea and high levels of MV infection in the URT, particularly in the nasal cavity. These novel findings have important implications for our understanding of the high transmissibility of measles.

Evolving treatment paradigms for chemotherapy-induced nausea and vomiting

BACKGROUND

Chemotherapy-induced nausea and vomiting (CINV) is one of the most debilitating toxicities associated with cancer treatment. Although effective antiemetic agents are available, their use in practice often is suboptimal.

METHODS

The author reviews the pathophysiology of CINV as well as the drug classes and cost considerations that should be incorporated into treatment planning.

RESULTS

Several drug classes, including 5-hydroxytryptamine-3 receptor antagonists, neurokinin-1 receptor antagonists, and corticosteroids, are effective, especially when used in combination. Older antiemetic agents, such as prochlorperazine and metoclopramide, as well as olanzapine may provide reasonable alternatives in certain settings.

CONCLUSIONS

Interventions for CINV should include standard-of-care antiemetics combined with corticosteroids. The cost of using older, less expensive antiemetics may be outweighed by the expenditures to rescue patients after suboptimal prophylaxis, as well as the indirect costs of missed work and lost productivity.

Imaging inflammation: molecular strategies to visualize key components of the inflammatory cascade, from initiation to resolution

Dysregulation of inflammation is central to the pathogenesis of innumerable human diseases. Understanding and tracking the critical events in inflammation are crucial for disease monitoring and pharmacological drug discovery and development. Recent progress in molecular imaging has provided novel insights into spatial associations, molecular events and temporal sequelae in the inflammatory process. While remaining a burgeoning field in pre-clinical research, increasing application in man affords researchers the opportunity to study disease pathogenesis in humans in situ thereby revolutionizing conventional understanding of pathophysiology and potential therapeutic targets. This review provides a description of commonly used molecular imaging modalities, including optical, radionuclide and magnetic resonance imaging, and details key advances and translational opportunities in imaging inflammation from initiation to resolution.

Sendai virus-based RSV vaccine protects African green monkeys from RSV infection

Respiratory syncytial virus (RSV) is a serious disease of children, responsible for an estimated 160,000 deaths per year worldwide. Despite the ongoing need for global prevention of RSV and decades of research, there remains no licensed vaccine. Sendai virus (SeV) is a mouse parainfluenza virus-type 1 which has been previously shown to confer protection against its human cousin, human parainfluenza virus-type 1 in African green monkeys (AGM). Here is described the study of a RSV vaccine (SeVRSV), produced by reverse genetics technology using SeV as a backbone to carry the full-length gene for RSV F. To test for immunogenicity, efficacy and safety, the vaccine was administered to AGM by intratracheal (i.t.) and intranasal (i.n.) routes. Control animals received the empty SeV vector or PBS. There were no booster immunizations. SeV and SeVRSV were cleared from the URT and LRT of vaccinated animals by day 10. Antibodies with specificities toward SeV and RSV were detected in SeVRSV primed animals as early as day ten after immunizations in both sera and nasal wash samples. One month after immunization all test and control AGM received an i.n. challenge with RSV-A2. SeVRSV-vaccinated animals exhibited reduced RSV in the URT compared to controls, and complete protection against RSV in the LRT. There were no clinically relevant adverse events associated with vaccination either before or after challenge. These data encourage advanced testing of the SeVRSV vaccine candidate in clinical trials for protection against RSV.