Protective efficacy of a plant-produced beta variant rSARS-CoV-2 VLP vaccine in golden Syrian hamsters

In the quest for heightened protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, we engineered a prototype vaccine utilizing the plant expression system of Nicotiana benthamiana, to produce a recombinant SARS-CoV-2 virus-like particle (VLP) vaccine presenting the S-protein from the Beta (B.1.351) variant of concern (VOC). This innovative vaccine, formulated with either a squalene oil-in-water emulsion or a synthetic CpG oligodeoxynucleotide adjuvant, demonstrated efficacy in a golden Syrian Hamster challenge model. The Beta VLP vaccine induced a robust humoral immune response, with serum exhibiting neutralization not only against SARS-CoV-2 Beta but also cross-neutralizing Delta and Omicron pseudoviruses. Protective efficacy was demonstrated, evidenced by reduced viral RNA copies and mitigated weight loss and lung damage compared to controls. This compelling data instills confidence in the creation of a versatile platform for the local manufacturing of potential pan-sarbecovirus vaccines, against evolving viral threats.

Proteomic and genetic analyses of influenza A viruses identify pan-viral host targets

Influenza A Virus (IAV) is a recurring respiratory virus with limited availability of antiviral therapies. Understanding host proteins essential for IAV infection can identify targets for alternative host-directed therapies (HDTs). Using affinity purification-mass spectrometry and global phosphoproteomic and protein abundance analyses using three IAV strains (pH1N1, H3N2, H5N1) in three human cell types (A549, NHBE, THP-1), we map 332 IAV-human protein-protein interactions and identify 13 IAV-modulated kinases. Whole exome sequencing of patients who experienced severe influenza reveals several genes, including scaffold protein AHNAK, with predicted loss-of-function variants that are also identified in our proteomic analyses. Of our identified host factors, 54 significantly alter IAV infection upon siRNA knockdown, and two factors, AHNAK and coatomer subunit COPB1, are also essential for productive infection by SARS-CoV-2. Finally, 16 compounds targeting our identified host factors suppress IAV replication, with two targeting CDK2 and FLT3 showing pan-antiviral activity across influenza and coronavirus families. This study provides a comprehensive network model of IAV infection in human cells, identifying functional host targets for pan-viral HDT.

LSDV-Vectored SARS-CoV-2 S and N Vaccine Protects against Severe Clinical Disease in Hamsters

The SARS-CoV-2 pandemic demonstrated the need for potent and broad-spectrum vaccines. This study reports the development and testing of a lumpy skin disease virus (LSDV)-vectored vaccine against SARS-CoV-2, utilizing stabilized spike and conserved nucleocapsid proteins as antigens to develop robust immunogenicity. Construction of the vaccine (LSDV-SARS2-S,N) was confirmed by polymerase chain reaction (PCR) amplification and sequencing. In vitro characterization confirmed that cells infected with LSDV-SARS2-S,N expressed SARS-CoV-2 spike and nucleocapsid protein. In BALB/c mice, the vaccine elicited high magnitude IFN-γ ELISpot responses (spike: 2808 SFU/10⁶ splenocytes) and neutralizing antibodies (ID₅₀ = 6552). Testing in hamsters, which emulate human COVID-19 disease progression, showed the development of high titers of neutralizing antibodies against the Wuhan and Delta SARS-CoV-2 variants (Wuhan ID₅₀ = 2905; Delta ID₅₀ = 4648). Additionally, hamsters vaccinated with LSDV-SARS2-S,N displayed significantly less weight loss, lung damage, and reduced viral RNA copies following SARS-CoV-2 infection with the Delta variant as compared to controls, demonstrating protection against disease. These data demonstrate that LSDV-vectored vaccines display promise as an effective SARS-CoV-2 vaccine and as a potential vaccine platform for communicable diseases in humans and animals. Further efficacy testing and immune response analysis, particularly in non-human primates, are warranted.

A plant-produced SARS-CoV-2 spike protein elicits heterologous immunity in hamsters

Molecular farming of vaccines has been heralded as a cheap, safe and scalable production platform. In reality, however, differences in the plant biosynthetic machinery, compared to mammalian cells, can complicate the production of viral glycoproteins. Remodelling the secretory pathway presents an opportunity to support key post-translational modifications, and to tailor aspects of glycosylation and glycosylation-directed folding. In this study, we applied an integrated host and glyco-engineering approach, NXS/T Generation™, to produce a SARS-CoV-2 prefusion spike trimer in Nicotiana benthamiana as a model antigen from an emerging virus. The size exclusion-purified protein exhibited a characteristic prefusion structure when viewed by transmission electron microscopy, and this was indistinguishable from the equivalent mammalian cell-produced antigen. The plant-produced protein was decorated with under-processed oligomannose N-glycans and exhibited a site occupancy that was comparable to the equivalent protein produced in mammalian cell culture. Complex-type glycans were almost entirely absent from the plant-derived material, which contrasted against the predominantly mature, complex glycans that were observed on the mammalian cell culture-derived protein. The plant-derived antigen elicited neutralizing antibodies against both the matched Wuhan and heterologous Delta SARS-CoV-2 variants in immunized hamsters, although titres were lower than those induced by the comparator mammalian antigen. Animals vaccinated with the plant-derived antigen exhibited reduced viral loads following challenge, as well as significant protection from SARS-CoV-2 disease as evidenced by reduced lung pathology, lower viral loads and protection from weight loss. Nonetheless, animals immunized with the mammalian cell-culture-derived protein were better protected in this challenge model suggesting that more faithfully reproducing the native glycoprotein structure and associated glycosylation of the antigen may be desirable.

Common and species-specific molecular signatures, networks, and regulators of influenza virus infection in mice, ferrets, and humans

Molecular responses to influenza A virus (IAV) infections vary between mammalian species. To identify conserved and species-specific molecular responses, we perform a comparative study of transcriptomic data derived from blood cells, primary epithelial cells, and lung tissues collected from IAV-infected humans, ferrets, and mice. The molecular responses in the human host have unique functions such as antigen processing that are not observed in mice or ferrets. Highly conserved gene coexpression modules across the three species are enriched for IAV infection-induced pathways including cell cycle and interferon (IFN) signaling. TDRD7 is predicted as an IFN-inducible host factor that is up-regulated upon IAV infection in the three species. TDRD7 is required for antiviral IFN response, potentially modulating IFN signaling via the JAK/STAT/IRF9 pathway. Identification of the common and species-specific molecular signatures, networks, and regulators of IAV infection provides insights into host-defense mechanisms and will facilitate the development of novel therapeutic interventions against IAV infection.

Functional landscape of SARS-CoV-2 cellular restriction

A deficient interferon (IFN) response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been implicated as a determinant of severe coronavirus disease 2019 (COVID-19). To identify the molecular effectors that govern IFN control of SARS-CoV-2 infection, we conducted a large-scale gain-of-function analysis that evaluated the impact of human IFN-stimulated genes (ISGs) on viral replication. A limited subset of ISGs were found to control viral infection, including endosomal factors inhibiting viral entry, RNA binding proteins suppressing viral RNA synthesis, and a highly enriched cluster of endoplasmic reticulum (ER)/Golgi-resident ISGs inhibiting viral assembly/egress. These included broad-acting antiviral ISGs and eight ISGs that specifically inhibited SARS-CoV-2 and SARS-CoV-1 replication. Among the broad-acting ISGs was BST2/tetherin, which impeded viral release and is antagonized by SARS-CoV-2 Orf7a protein. Overall, these data illuminate a set of ISGs that underlie innate immune control of SARS-CoV-2/SARS-CoV-1 infection, which will facilitate the understanding of host determinants that impact disease severity and offer potential therapeutic strategies for COVID-19.

High burden of viral respiratory co-infections in a cohort of children with suspected pulmonary tuberculosis

Background

The presentation of pulmonary tuberculosis (PTB) in young children is often clinically indistinguishable from other common respiratory illnesses, which are frequently infections of viral aetiology. As little is known about the role of viruses in children with PTB, we investigated the prevalence of respiratory viruses in children with suspected PTB at presentation and follow-up.

Methods

In an observational cohort study, children < 13 years were routinely investigated for suspected PTB in Cape Town, South Africa between December 2015 and September 2017 and followed up for 24 weeks. Nasopharyngeal aspirates (NPAs) were tested for respiratory viruses using multiplex PCR at enrolment, week 4 and 8.

Results

Seventy-three children were enrolled [median age 22.0 months; (interquartile range 10.0–48.0); 56.2% male and 17.8% HIV-infected. Anti-tuberculosis treatment was initiated in 54.8%; of these 50.0% had bacteriologically confirmed TB. At enrolment, ≥1 virus were detected in 95.9% (70/73) children; most commonly human rhinovirus (HRV) (74.0%). HRV was more frequently detected in TB cases (85%) compared to ill controls (60.6%) (p = 0.02). Multiple viruses were detected in 71.2% of all children; 80% of TB cases and 60.6% of ill controls (p = 0.07). At follow-up, ≥1 respiratory virus was detected in 92.2% (47/51) at week 4, and 94.2% (49/52) at week 8.

Conclusions

We found a high prevalence of viral respiratory co-infections in children investigated for PTB, irrespective of final PTB diagnosis, which remained high during follow up. Future work should include investigating the whole respiratory ecosystem in combination with pathogen- specific immune responses.

Functional Landscape of SARS-CoV-2 Cellular Restriction

A deficient interferon response to SARS-CoV-2 infection has been implicated as a determinant of severe COVID-19. To identify the molecular effectors that govern interferon control of SARS-CoV-2 infection, we conducted a large-scale gain-of-function analysis that evaluated the impact of human interferon stimulated genes (ISGs) on viral replication. A limited subset of ISGs were found to control viral infection, including endosomal factors that inhibited viral entry, nucleic acid binding proteins that suppressed viral RNA synthesis, and a highly enriched cluster of ER and Golgi-resident ISGs that inhibited viral translation and egress. These included the type II integral membrane protein BST2/tetherin, which was found to impede viral release, and is targeted for immune evasion by SARS-CoV-2 Orf7a protein. Overall, these data define the molecular basis of early innate immune control of viral infection, which will facilitate the understanding of host determinants that impact disease severity and offer potential therapeutic strategies for COVID-19.

An Influenza Virus Entry Inhibitor Targets Class II PI3 Kinase and Synergizes with Oseltamivir

Two classes of antivirals targeting the viral neuraminidase (NA) and endonuclease are currently the only clinically useful drugs for the treatment of influenza. However, resistance to both antivirals has been observed in clinical isolates, and there was widespread resistance to oseltamivir (an NA inhibitor) among H1N1 viruses prior to 2009. This potential for resistance and lack of diversity for antiviral targets highlights the need for new influenza antivirals with a higher barrier to resistance. In this study, we identified an antiviral compound, M85, that targets host kinases, epidermal growth factor receptor (EGFR), and phosphoinositide 3 class II β (PIK3C2β) and is not susceptible to resistance by viral mutations. M85 blocks endocytosis of influenza viruses and inhibits a broad-spectrum of viruses with minimal cytotoxicity. In vitro, we found that combinations of M85 and oseltamivir have strong synergism. In the mouse model for influenza, treatment with the combination therapy was more protective against a lethal viral challenge than oseltamivir alone, indicating that development of M85 could lead to combination therapies for influenza. Finally, through this discovery of M85 and its antiviral mechanism, we present the first description of PIK3C2β as a necessary host factor for influenza virus entry.

Baloxavir marboxil: the new influenza drug on the market

For the first time in nearly 20 years there is a new class of antiviral drug for influenza. The latest approved antiviral is baloxavir marboxil (trade name, Xofluza) which targets the endonuclease function of the viral PA polymerase subunit and prevents the transcription of viral mRNA. The most promising aspect of this new drug is its pharmacology which allows for effective treatment of influenza A or B virus infection with just a single dose. A clinical trial showed greater reductions in viral loads with baloxavir marboxil treatment compared with oseltamivir, although no difference in the time to alleviation of symptoms between these two drugs. With this new class of influenza drug comes exciting prospects for combination therapy with the neuraminidase inhibitors which may help to abate concerns about the development of resistance.

Transcription Elongation Can Affect Genome 3D Structure

How transcription affects genome 3D organization is not well understood. We found that during influenza A (IAV) infection, rampant transcription rapidly reorganizes host cell chromatin interactions. These changes occur at the ends of highly transcribed genes, where global inhibition of transcription termination by IAV NS1 protein causes readthrough transcription for hundreds of kilobases. In these readthrough regions, elongating RNA polymerase II disrupts chromatin interactions by inducing cohesin displacement from CTCF sites, leading to locus decompaction. Readthrough transcription into heterochromatin regions switches them from the inert (B) to the permissive (A) chromatin compartment and enables transcription factor binding. Data from non-viral transcription stimuli show that transcription similarly affects cohesin-mediated chromatin contacts within gene bodies. Conversely, inhibition of transcription elongation allows cohesin to accumulate at previously transcribed intragenic CTCF sites and to mediate chromatin looping and compaction. Our data indicate that transcription elongation by RNA polymerase II remodels genome 3D architecture.

Paramyxovirus V Proteins Interact with the RIG-I/TRIM25 Regulatory Complex and Inhibit RIG-I Signaling

Paramyxovirus V proteins are known antagonists of the RIG-I-like receptor (RLR)-mediated interferon induction pathway, interacting with and inhibiting the RLR MDA5. We report interactions between the Nipah virus V protein and both RIG-I regulatory protein TRIM25 and RIG-I. We also observed interactions between these host proteins and the V proteins of measles virus, Sendai virus, and parainfluenza virus. These interactions are mediated by the conserved C-terminal domain of the V protein, which binds to the tandem caspase activation and recruitment domains (CARDs) of RIG-I (the region of TRIM25 ubiquitination) and to the SPRY domain of TRIM25, which mediates TRIM25 interaction with the RIG-I CARDs. Furthermore, we show that V interaction with TRIM25 and RIG-I prevents TRIM25-mediated ubiquitination of RIG-I and disrupts downstream RIG-I signaling to the mitochondrial antiviral signaling protein. This is a novel mechanism for innate immune inhibition by paramyxovirus V proteins, distinct from other known V protein functions such as MDA5 and STAT1 antagonism.IMPORTANCE The host RIG-I signaling pathway is a key early obstacle to paramyxovirus infection, as it results in rapid induction of an antiviral response. This study shows that paramyxovirus V proteins interact with and inhibit the activation of RIG-I, thereby interrupting the antiviral signaling pathway and facilitating virus replication.

Broad Spectrum Inhibitor of Influenza A and B Viruses Targeting the Viral Nucleoprotein

S119 was a top hit from an ultrahigh throughput screen performed to identify novel inhibitors of influenza virus replication. It showed a potent antiviral effect (50% inhibitory concentration, IC50 = 20 nM) and no detectable cytotoxicity (50% cytotoxic concentration, CC50 > 500 μM) to yield a selectivity index greater than 25 000. Upon investigation, we found that S119 selected for resistant viruses carrying mutations in the viral nucleoprotein (NP). These resistance mutations highlight a likely S119 binding site overlapping with but not identical to that found for the compound nucleozin. Mechanism of action studies revealed that S119 affects both the oligomerization state and cellular localization of the NP protein which has an impact on viral transcription, replication, and protein expression. Through a hit-to-lead structure-activity relationship (SAR) study, we found an analog of S119, named S119-8, which had increased breadth of inhibition against influenza A and B viruses accompanied by only a small loss in potency. Finally, in vitro viral inhibition assays showed a synergistic relationship between S119-8 and oseltamivir when they were combined, indicating the potential for future drug cocktails.

SMARCA2-regulated host cell factors are required for MxA restriction of influenza A viruses

The human interferon (IFN)-induced MxA protein is a key antiviral host restriction factor exhibiting broad antiviral activity against many RNA viruses, including highly pathogenic avian influenza A viruses (IAV) of the H5N1 and H7N7 subtype. To date the mechanism for how MxA exerts its antiviral activity is unclear, however, additional cellular factors are believed to be essential for this activity. To identify MxA cofactors we performed a genome-wide siRNA-based screen in human airway epithelial cells (A549) constitutively expressing MxA using an H5N1 reporter virus. These data were complemented with a proteomic screen to identify MxA-interacting proteins. The combined data identified SMARCA2, the ATPase subunit of the BAF chromatin remodeling complex, as a crucial factor required for the antiviral activity of MxA against IAV. Intriguingly, our data demonstrate that although SMARCA2 is essential for expression of some IFN-stimulated genes (ISGs), and the establishment of an antiviral state, it is not required for expression of MxA, suggesting an indirect effect on MxA activity. Transcriptome analysis of SMARCA2-depleted A549-MxA cells identified a small set of SMARCA2-regulated factors required for activity of MxA, in particular IFITM2 and IGFBP3. These findings reveal that several virus-inducible factors work in concert to enable MxA restriction of IAV.

Influenza

Influenza is an infectious respiratory disease that, in humans, is caused by influenza A and influenza B viruses. Typically characterized by annual seasonal epidemics, sporadic pandemic outbreaks involve influenza A virus strains of zoonotic origin. The WHO estimates that annual epidemics of influenza result in ~1 billion infections, 3–5 million cases of severe illness and 300,000–500,000 deaths. The severity of pandemic influenza depends on multiple factors, including the virulence of the pandemic virus strain and the level of pre-existing immunity. The most severe influenza pandemic, in 1918, resulted in >40 million deaths worldwide. Influenza vaccines are formulated every year to match the circulating strains, as they evolve antigenically owing to antigenic drift. Nevertheless, vaccine efficacy is not optimal and is dramatically low in the case of an antigenic mismatch between the vaccine and the circulating virus strain. Antiviral agents that target the influenza virus enzyme neuraminidase have been developed for prophylaxis and therapy. However, the use of these antivirals is still limited. Emerging approaches to combat influenza include the development of universal influenza virus vaccines that provide protection against antigenically distant influenza viruses, but these vaccines need to be tested in clinical trials to ascertain their effectiveness.

The Next Wave of Influenza Drugs

Options for influenza therapy are currently limited to one class of drug, the neuraminidase inhibitors. Amidst concerns about drug resistance, much effort has been placed on the discovery of new drugs with distinct targets and mechanisms of action, with great success. There are now several candidates in late stage development which include small molecules targeting the three subunits of the viral polymerase complex and monoclonal antibodies targeting the hemagglutinin, as well as host-directed therapies. The availability of drugs with diverse mechanisms now opens the door to exploring combination therapies for influenza, and the range of administration routes presents more opportunities for treating hospitalized patients.

High-Throughput Minigenome System for Identifying Small-Molecule Inhibitors of Ebola Virus Replication

Ebola virus (EBOV), a member of the family Filoviridae, is a nonsegmented negative-sense RNA virus that causes severe, often lethal, disease in humans. EBOV RNA synthesis is carried out by a complex that includes several viral proteins. The function of this machinery is essential for viral gene expression and viral replication and is therefore a potential target for antivirals. We developed and optimized a high-throughput screening (HTS) assay based on an EBOV minigenome assay, which assesses the function of the polymerase complex. The assay is robust in 384-well format and displays a large signal to background ratio and high Z-factor values. We performed a pilot screen of 2080 bioactive compounds, identifying 31 hits (1.5% of the library) with >70% inhibition of EBOV minigenome activity. We further identified eight compounds with 50% inhibitory concentrations below their 50% cytotoxic concentrations, five of which had selectivity index (SI) values >10, suggesting specificity against the EBOV polymerase complex. These included an inhibitor of inosine monophosphate dehydrogenase, a target known to modulate the EBOV replication complex. They also included novel classes of inhibitors, including inhibitors of protein synthesis and hypoxia inducible factor-1. Five compounds were tested for their ability to inhibit replication of a recombinant EBOV that expresses GFP (EBOV-GFP), and four inhibited EBOV-GFP growth at sub-cytotoxic concentrations. These data demonstrate the utility of the HTS minigenome assay for drug discovery and suggest potential directions for antifiloviral drug development.

A Potent Anti-influenza Compound Blocks Fusion through Stabilization of the Prefusion Conformation of the Hemagglutinin Protein

An ultrahigh-throughput screen was performed to identify novel small molecule inhibitors of influenza virus replication. The screen employed a recombinant influenza A/WSN/33 virus expressing Renilla luciferase and yielded a hit rate of 0.5%, of which the vast majority showed little cytotoxicity at the inhibitory concentration. One of the top hits from this screen, designated S20, inhibits HA-mediated membrane fusion. S20 shows potent antiviral activity (IC₅₀ = 80 nM) and low toxicity (CC₅₀ = 40 μM), yielding a selectivity index of 500 and functionality against all of the group 1 influenza A viruses tested in this study, including the pandemic H1N1 and avian H5N1 viruses. Mechanism of action studies proved a direct S20–HA interaction and showed that S20 inhibits fusion by stabilizing the prefusion conformation of HA. In silico docking studies were performed, and the predicted binding site in HA2 corresponds with the area where resistance mutations occurred and correlates with the known role of this region in fusion. This high-throughput screen has yielded many promising new lead compounds, including S20, which will potentially shed light on the molecular mechanisms of viral infection and serve as research tools or be developed for clinical use as antivirals.

New-generation screening assays for the detection of anti-influenza compounds targeting viral and host functions

Current options for influenza antiviral therapy are limited to the neuraminidase inhibitors, and knowledge that high levels of oseltamivir resistance have been seen among previously circulating H1N1 viruses increases the urgency to find new influenza therapeutics. To feed this pipeline, assays that are appropriate for use in high-throughput screens are being developed and are discussed in this review. Particular emphasis is placed on cell-based assays that capture both inhibitors of viral functions as well as the host functions that facilitate optimal influenza virus replication. Success in this area has been fueled by a greater understanding of the genome structure of influenza viruses and the ability to generate replication-competent recombinant viruses that carry a reporter gene, allowing for easy monitoring of viral infection in a high-throughput setting. This article forms part of a symposium in Antiviral Research on "Treatment of influenza: targeting the virus or the host."

Identification of small molecules with type I interferon inducing properties by high-throughput screening

The continuous emergence of virus that are resistant to current anti-viral drugs, combined with the introduction of new viral pathogens for which no therapeutics are available, creates an urgent need for the development of novel broad spectrum antivirals. Type I interferon (IFN) can, by modulating the cellular expression profile, stimulate a non-specific antiviral state. The antiviral and adjuvant properties of IFN have been extensively demonstrated; however, its clinical application has been so far limited. We have developed a human cell-based assay that monitors IFN-β production for use in a high throughput screen. Using this assay we screened 94,398 small molecules and identified 18 compounds with IFN-inducing properties. Among these, 3 small molecules (C3, E51 and L56) showed activity not only in human but also in murine and canine derived cells. We further characterized C3 and showed that this molecule is capable of stimulating an anti-viral state in human-derived lung epithelial cells. Furthermore, the IFN-induction by C3 is not diminished by the presence of influenza A virus NS1 protein or hepatitis C virus NS3/4A protease, which make this molecule an interesting candidate for the development of a new type of broad-spectrum antiviral. In addition, the IFN-inducing properties of C3 also suggest its potential use as vaccine adjuvant.

A novel small molecule inhibitor of influenza A viruses that targets polymerase function and indirectly induces interferon

Influenza viruses continue to pose a major public health threat worldwide and options for antiviral therapy are limited by the emergence of drug-resistant virus strains. The antiviral cytokine, interferon (IFN) is an essential mediator of the innate immune response and influenza viruses, like many viruses, have evolved strategies to evade this response, resulting in increased replication and enhanced pathogenicity. A cell-based assay that monitors IFN production was developed and applied in a high-throughput compound screen to identify molecules that restore the IFN response to influenza virus infected cells. We report the identification of compound ASN2, which induces IFN only in the presence of influenza virus infection. ASN2 preferentially inhibits the growth of influenza A viruses, including the 1918 H1N1, 1968 H3N2 and 2009 H1N1 pandemic strains and avian H5N1 virus. In vivo, ASN2 partially protects mice challenged with a lethal dose of influenza A virus. Surprisingly, we found that the antiviral activity of ASN2 is not dependent on IFN production and signaling. Rather, its IFN-inducing property appears to be an indirect effect resulting from ASN2-mediated inhibition of viral polymerase function, and subsequent loss of the expression of the viral IFN antagonist, NS1. Moreover, we identified a single amino acid mutation at position 499 of the influenza virus PB1 protein that confers resistance to ASN2, suggesting that PB1 is the direct target. This two-pronged antiviral mechanism, consisting of direct inhibition of virus replication and simultaneous activation of the host innate immune response, is a unique property not previously described for any single antiviral molecule.

Influenza viruses are rapidly developing resistance against available anti-influenza drugs and consequently there is an urgent demand for new treatment approaches. We identified compound ASN2 in a high-throughput screen for molecules that are capable of inducing the antiviral cytokine interferon (IFN) in the presence of influenza virus infection. Normally, influenza virus blocks IFN production, an activity that is dependent on the viral NS1 protein and contributes to the ability of the virus to cause disease in an infected host. We show that ASN2 is a potent inhibitor of influenza A virus and can partially protect infected animals from disease and death. ASN2 acts by targeting influenza virus polymerase function which results in inhibition of virus replication, and as a consequence, NS1 expression. Thus the ability of ASN2 to induce IFN is a “side-effect”, albeit a desirable one, of polymerase inhibition. This combination of directly inhibiting the virus while also stimulating the host immune response is a novel property for an antiviral compound.

The host interactome of influenza virus presents new potential targets for antiviral drugs

Increasing antiviral drug resistance is a major concern for treating influenza, especially in a pandemic setting when the availability of a protective vaccine is uncertain. Resistance is often an issue with drugs directed at viral proteins and for small RNA viruses; there are also a limited number of viral proteins that are amenable to inhibition by a small molecule. A new approach that is gaining support is that cellular proteins, which facilitate virus replication, may be used as alternative targets. Whereas drugs directed at viral proteins tend to be virus-specific, drugs directed at host targets have the potential to have broad-spectrum antiviral activity as many viruses may share a dependency on that host function. For influenza virus, we have very limited knowledge of which cellular factors are involved in virus replication, let alone which of these have suitable properties to serve as drug targets. Through the use of high-throughput RNA interference screens, several studies have addressed this gap in our knowledge. The resulting datasets provide new insight into host pathways that are involved in the influenza virus replication cycle and identify specific host factors in these pathways that may serve as potential targets for future antiviral drug development.

Uncovering the global host cell requirements for influenza virus replication via RNAi screening

Influenza virus is reliant on numerous host cell functions during its replication cycle. RNA interference technology, applied on a genome-wide level, has identified human host factors that are necessary for efficient virus replication and provides new insight into how influenza virus interacts with its host at the molecular level.

Human host factors required for influenza virus replication

Influenza A virus is an RNA virus that encodes up to 11 proteins and this small coding capacity demands that the virus use the host cellular machinery for many aspects of its life cycle. Knowledge of these host cell requirements not only informs us of the molecular pathways exploited by the virus but also provides further targets that could be pursued for antiviral drug development. Here we use an integrative systems approach, based on genome-wide RNA interference screening, to identify 295 cellular cofactors required for early-stage influenza virus replication. Within this group, those involved in kinase-regulated signalling, ubiquitination and phosphatase activity are the most highly enriched, and 181 factors assemble into a highly significant host-pathogen interaction network. Moreover, 219 of the 295 factors were confirmed to be required for efficient wild-type influenza virus growth, and further analysis of a subset of genes showed 23 factors necessary for viral entry, including members of the vacuolar ATPase (vATPase) and COPI-protein families, fibroblast growth factor receptor (FGFR) proteins, and glycogen synthase kinase 3 (GSK3)-beta. Furthermore, 10 proteins were confirmed to be involved in post-entry steps of influenza virus replication. These include nuclear import components, proteases, and the calcium/calmodulin-dependent protein kinase (CaM kinase) IIbeta (CAMK2B). Notably, growth of swine-origin H1N1 influenza virus is also dependent on the identified host factors, and we show that small molecule inhibitors of several factors, including vATPase and CAMK2B, antagonize influenza virus replication.

Henipaviruses employ a multifaceted approach to evade the antiviral interferon response

Hendra and Nipah virus, which constitute the genus Henipavirus, are zoonotic paramyxoviruses that have been associated with sporadic outbreaks of severe disease and mortality in humans since their emergence in the late 1990s. Similar to other paramyxoviruses, their ability to evade the host interferon (IFN) response is conferred by the P gene. The henipavirus P gene encodes four proteins; the P, V, W and C proteins, which have all been described to inhibit the antiviral response. Further studies have revealed that these proteins have overlapping but unique properties which enable the virus to block multiple signaling pathways in the IFN response. The best characterized of these is the JAK-STAT signaling pathway which is targeted by the P, V and W proteins via an interaction with the transcription factor STAT1. In addition the V and W proteins can both limit virus-induced induction of IFN but they appear to do this via distinct mechanisms that rely on unique sequences in their C-terminal domains. The ability to generate recombinant Nipah viruses now gives us the opportunity to determine the precise role for each of these proteins and address their contribution to pathogenicity. Additionally, the question of whether these multiple anti-IFN strategies are all active in the different mammalian hosts for henipaviruses, particularly the fruit bat reservoir, warrants further exploration.

Modulation of influenza virus replication by alteration of sodium ion transport and protein kinase C activity

In recent years, increasing levels of resistance to the four FDA-approved anti-influenza virus drugs have been described and vaccine manufacturers have experienced demands that exceed their capacity. This situation underlines the urgent need for novel antivirals as well as innovations in vaccine production in preparation for the next influenza epidemic. Here we report the development of a cell-based high-throughput screen which we have used for the identification of compounds that modulate influenza virus growth either negatively or positively. We screened a library of compounds with known biological activity and identified distinct groups of inhibitors and enhancers that target sodium channels or protein kinase C (PKC). We confirmed these results in viral growth assays and find that treatment with a sodium channel opener or PKC inhibitor significantly reduces viral replication. In contrast, inhibition of sodium channels or activation of PKC leads to enhanced virus production in tissue culture. These diametrically opposing effects strongly support a role for PKC activity and the regulation of Na⁺ currents in influenza virus replication and both may serve as targets for antiviral drugs. Furthermore, we raise the possibility that compounds that result in increased viral titers may be beneficial for boosting the production of tissue culture-grown influenza vaccines.

Ebola virus VP24 binds karyopherin alpha1 and blocks STAT1 nuclear accumulation

Ebola virus (EBOV) infection blocks cellular production of alpha/beta interferon (IFN-alpha/beta) and the ability of cells to respond to IFN-alpha/beta or IFN-gamma. The EBOV VP35 protein has previously been identified as an EBOV-encoded inhibitor of IFN-alpha/beta production. However, the mechanism by which EBOV infection inhibits responses to IFNs has not previously been defined. Here we demonstrate that the EBOV VP24 protein functions as an inhibitor of IFN-alpha/beta and IFN-gamma signaling. Expression of VP24 results in an inhibition of IFN-induced gene expression and an inability of IFNs to induce an antiviral state. The VP24-mediated inhibition of cellular responses to IFNs correlates with the impaired nuclear accumulation of tyrosine-phosphorylated STAT1 (PY-STAT1), a key step in both IFN-alpha/beta and IFN-gamma signaling. Consistent with this proposed function for VP24, infection of cells with EBOV also confers a block to the IFN-induced nuclear accumulation of PY-STAT1. Further, VP24 is found to specifically interact with karyopherin alpha1, the nuclear localization signal receptor for PY-STAT1, but not with karyopherin alpha2, alpha3, or alpha4. Overexpression of VP24 results in a loss of karyopherin alpha1-PY-STAT1 interaction, indicating that the VP24-karyopherin alpha1 interaction contributes to the block to IFN signaling. These data suggest that VP24 is likely to be an important virulence determinant that allows EBOV to evade the antiviral effects of IFNs.

Nuclear localization of the Nipah virus W protein allows for inhibition of both virus- and toll-like receptor 3-triggered signaling pathways

The Nipah virus V and W proteins, which are encoded by the P gene via RNA editing, have a common N-terminal domain but unique C-terminal domains. They localize to the cytoplasm and nucleus, respectively, and have both been shown to function as inhibitors of JAK/STAT signaling. Here we report that V and W proteins also block virus activation of the beta interferon (IFN-beta) promoter and the IFN regulatory factor 3 (IRF3)-responsive IFN-stimulated gene 54 promoter. Surprisingly, only W protein shows strong inhibition of promoter activation in response to stimulation of Toll-like receptor 3 (TLR3) by extracellular double-stranded RNA. This activity is dependent on the nuclear localization of W protein. Within the unique C-terminal domain of W protein, we have identified a nuclear localization signal (NLS) that requires basic residues at positions 439, 440, and 442. This NLS is responsible for mediating the preferential interaction of W protein with karyopherin-alpha 3 and karyopherin-alpha 4. Nuclear localization of W protein therefore enables it to target both virus and TLR3 pathways, whereas the cytoplasmic V protein is restricted to inhibiting the virus pathway. We propose that this discrepancy is in part due to the V protein being less able to block signaling in response to the kinase, TBK-1, whereas both V and W can prevent promoter activation in response to IKKepsilon. We demonstrate that, when the TLR3 pathway is stimulated, the levels of phosphorylated IRF3 are reduced in the presence of W protein but not V protein, confirming the differential effects of these proteins and illustrating that W protein-mediated inhibition is due to a loss of active IRF3.

Nipah virus V and W proteins have a common STAT1-binding domain yet inhibit STAT1 activation from the cytoplasmic and nuclear compartments, respectively

In previous reports it was demonstrated that the Nipah virus V and W proteins have interferon (IFN) antagonist activity due to their ability to block signaling from the IFN-alpha/beta receptor (J. J. Rodriguez, J. P. Parisien, and C. M. Horvath, J. Virol. 76:11476-11483, 2002; M. S. Park et al., J. Virol. 77:1501-1511, 2003). The V, W, and P proteins are all encoded by the same viral gene and share an identical 407-amino-acid N-terminal region but have distinct C-terminal sequences. We now show that the P protein also has anti-IFN function, confirming that the common N-terminal domain is responsible for the antagonist activity. Truncation of this N-terminal domain revealed that amino acids 50 to 150 retain the ability to block IFN and to bind STAT1, a key component of the IFN signaling pathway. Subcellular localization studies demonstrate that the V and P proteins are predominantly cytoplasmic whereas the W protein is localized to the nucleus. In all cases, STAT1 colocalizes with the corresponding Nipah virus protein. These interactions are sufficient to inhibit STAT1 activation, as demonstrated by the lack of STAT1 phosphorylation on tyrosine 701 in IFN-stimulated cells expressing P, V, or W. Therefore, despite their common STAT1-binding domain, the Nipah virus V and P proteins act by retaining STAT1 in the cytoplasm while the W protein sequesters STAT1 in the nucleus, creating both a cytoplasmic and a nuclear block for STAT1. We also show that the IFN antagonist activity of the P protein is not as strong as that of V or W, perhaps explaining why Nipah virus has evolved to express these two edited products.

Characterisation of the differences between hepatitis C virus genotype 3 and 1 glycoproteins

Sequence variation in the envelope E1 and E2 glycoproteins of hepatitis C virus (HCV) could account for differences in disease pathogenesis in patients infected with different genotypes. A cDNA encoding the structural region of the hepatitis C polyprotein was constructed to match the majority sequence of viral RNA extracted from a patient infected with genotype 3a (designated strain HCV3a-Gla). The principal differences predicted between E2 of HCV3a-Gla and the corresponding H77c genotype 1a protein were that the former contained six more amino acids (361 vs. 355), but it had one fewer glycosylation site. Expression studies showed that, in common with the H77c glycoproteins, E1 and E2 from HCV3a-Gla localised to the endoplasmic reticulum (ER) membrane in both Huh-7 and BHK tissue culture cells and interacted to form native complexes. Analysis of the cross-reactivity of antibodies raised against glycoproteins of genotype 1a strains showed that three of five monoclonal antibodies that recognise linear epitopes were able to detect E2 from strain HCV3a-Gla. However, neither conformational E2 antibodies nor antibodies raised against E1 were able to detect the HCV3a-Gla glycoproteins. In receptor binding assays, E2 of HCV3a-Gla consistently failed to bind CD81, a putative cell receptor for HCV. Absence of binding to CD81 and lack of recognition by most antibodies raised to genotype 1a glycoproteins indicate important differences between these glycoproteins representative of genotypes 3a and 1a. These may be pertinent to the differences in response to interferon therapy and the prevalence of steatosis reported in patients infected with these genotypes.

Measurement of beryllium in lung tissue of a chronic beryllium disease case and cases with sarcoidosis

BACKGROUND

The clinical features of chronic beryllium disease (CBD) are similar to many other chronic lung diseases. In particular, it may be difficult to distinguish it from pulmonary sarcoidosis since the two conditions may be very alike in clinical, pathological and radiological features. Aim To determine if the amount of beryllium found in the lungs could be used to differentiate CBD from sarcoidosis and controls.

METHODS

Analyses for beryllium in the autopsied lung tissues of 29 cases and controls were carried out. The cases included one CBD, three confirmed sarcoidosis and 25 controls. Blocks of formalin-fixed tissues were analysed by an atomic absorption spectrophotometer equipped with a graphite furnace. A method for analysis of beryllium in air was modified to permit tissue analysis.

RESULTS

The CBD case had a much higher average beryllium level, but some individual results were similar to controls and patients with sarcoidosis.

CONCLUSION

The CBD case had beryllium levels within the range of values reported in the literature. The differentiation between CBD and sarcoidosis could not be made with reasonable assurance based only on the analytic result. Occupational history is very important in making a diagnosis of CBD, along with the analysis of tissues. Tissue analysis helped confirm the diagnosis of compensatable CBD in this particular case.

Newcastle disease virus (NDV)-based assay demonstrates interferon-antagonist activity for the NDV V protein and the Nipah virus V, W, and C proteins

We have generated a recombinant Newcastle disease virus (NDV) that expresses the green fluorescence protein (GFP) in infected chicken embryo fibroblasts (CEFs). This virus is interferon (IFN) sensitive, and pretreatment of cells with chicken alpha/beta IFN (IFN-alpha/beta) completely blocks viral GFP expression. Prior transfection of plasmid DNA induces an IFN response in CEFs and blocks NDV-GFP replication. However, transfection of known inhibitors of the IFN-alpha/beta system, including the influenza A virus NS1 protein and the Ebola virus VP35 protein, restores NDV-GFP replication. We therefore conclude that the NDV-GFP virus could be used to screen proteins expressed from plasmids for the ability to counteract the host cell IFN response. Using this system, we show that expression of the NDV V protein or the Nipah virus V, W, or C proteins rescues NDV-GFP replication in the face of the transfection-induced IFN response. The V and W proteins of Nipah virus, a highly lethal pathogen in humans, also block activation of an IFN-inducible promoter in primate cells. Interestingly, the amino-terminal region of the Nipah virus V protein, which is identical to the amino terminus of Nipah virus W, is sufficient to exert the IFN-antagonist activity. In contrast, the anti-IFN activity of the NDV V protein appears to be located in the carboxy-terminal region of the protein, a region implicated in the IFN-antagonist activity exhibited by the V proteins of mumps virus and human parainfluenza virus type 2.

Preclinical safety testing of DISC-hGMCSF to support phase I clinical trials in cancer patients

BACKGROUND

DISC-hGMCSF is a gH-deleted HSV-2 based vector expressing human GM-CSF that is being developed for cancer immunotherapy. To support first clinical use, a range of preclinical safety studies were performed using DISC-hGMCSF in addition to DISC-murine-GMCSF and the backbone vector, TA-HSV.

METHODS

The toxicity of the DISC vectors was assessed by repeated dose, neurovirulence and neuroinvasiveness studies in mice, and by safety studies in rabbits, guinea pigs and athymic nude mice. Studies were also conducted to determine whether the vector could establish latency in local ganglia in mice following intradermal injection, and whether it could reactivate from the latent state. The vector biodistribution following intravenous administration was also investigated in mice, using PCR to detect vector DNA.

RESULTS

The DISC vectors were essentially non-toxic in all the systems studied. No adverse reactions were seen in mice receiving four intravenous doses of DISC-mGMCSF and the results from studies of neurovirulence, neuroinvasiveness, local tolerance in rabbit, general safety in mice and guinea pigs and safety in athymic nude mice were consistent with DISC being unable to replicate and cause disease. The vector could establish latency in local ganglia in mice, but at low efficiency, and could not reactivate infectious virions. Following intravenous administration, vector DNA was widely distributed up to Day 28, but by Day 56 had disappeared from gonads and brain and was only found in blood and liver.

CONCLUSION

The panel of safety studies provided evidence that DISC-hGMCSF will be unable to replicate and cause disease, and has low toxicity in man. These data were presented to the Medicines Control Agency and the Gene Therapy Advisory Committee as part of the regulatory submissions for a clinical trial in melanoma patients. These submissions have been approved, and DISC-hGMCSF has now entered a phase I clinical trial in the UK by direct intratumoural injection.

Benzene and total hydrocarbons exposures in the downstream petroleum industries

A review of studies, including both articles published in peer-reviewed journals and reports that were not peer reviewed, regarding occupational exposure to benzene and total hydrocarbons in the downstream petroleum industry operations was performed. The objective was to provide a broad estimate of exposures by compiling exposure data according to the following categories: refinery, pipeline, marine, rail, bulk terminals and trucks, service stations, underground storage tanks, tank cleaning, and site remediations. The data in each category was divided into personal occupational long-term and short-term samples. The summarized data offers valuable assistance to hygienists by providing them with an estimate and range of exposures. The traditional 8-hour time-weighted average (TWA) exposure and the 40-hour workweek do not generally coincide with exposure periods applicable to workers in marine, pipeline, railcar, and trucking operations. They are more comparable with short-term exposure or task-based exposure assessments. The marine sector has a large number of high exposures. Although relatively few workers are exposed, their exposures to benzene and total hydrocarbons are sometimes an order of magnitude higher than the respective exposure limits. It is recommended that in the future, it would be preferable to do more task-based exposure assessments and fewer traditional TWA long-term exposure assessments within the various sectors of the downstream petroleum industry.

The amino acid sequence of the PKR-eIF2alpha phosphorylation homology domain of hepatitis C virus envelope 2 protein and response to interferon-alpha

A region of the hepatitis C virus (HCV) envelope 2 protein, the protein kinase, PKR and early initiation factor 2alpha phosphorylation homology domain (PePHD), may be important in interferon (IFN)-alpha resistance. The PePHD was amplified by polymerase chain reaction and sequenced, and the amino acid sequence derived from pretreatment serum of 14 genotype 3-infected patients with a range of responses to IFN-alpha therapy. Only 1 patient had a PePHD variant. IFN-resistant PePHD variants present at low titers in pretreatment serum should be selected by therapy; therefore, the PePHD amino acid sequence was also obtained from serum collected during or after treatment in 5 patients with breakthrough or relapse of HCV RNA positivity. No difference was found between the pre- and posttreatment PePHD sequences. Thus, it appears that pretreatment sequencing of the PePHD would not enable clinicians to predict the treatment response. There was no evidence that IFN therapy exerts selection pressure in this region.

S-alk(en)yl-L-cysteine sulfoxides, alliinase and aroma in Leucocoryne

Levels of S-alk(en)yl-L-cysteine sulfoxides, alliinase and enzymatically generated pyruvic acid were determined in the bulb, leaf and scape of five species and a natural hybrid of Leucocoryne (Liliaceae), a genus of ornamental geophytes indigenous to Chile. (+)-S-Methyl-L-cysteine sulfoxide (MCSO) was present in all plant parts of all species at levels between 0.09 and 1.41 mg g(-1) fr. wt. Trans-(+)-S-(1-propenyl)-L-cysteine sulfoxide (PRENCSO) was present in plant parts of three species only (L. angustipetala, L. oadorata and L. purpurea) at levels between 0.12 and 1.82 mg g(-1) fr. wt. No other S-alk(en)yl-L-cysteine sulfoxides were detected. Alliinase (EC 4.4.1.4) was detected in the leaf, bulb and scape of L. angustipetala and L. purpurea, only in the leaves of L. coquimbensis and L. purpurea x L. coquimbensis, and only in the bulb of L. odorata. Enzymatically generated pyruvic acid was detected in all plant parts of all species at levels between trace amounts and 5.33 micromol g(-1) fr. wt. As PRENCSO is produced only in Leucocoryne species exhibiting a strong and unpleasant onion-like aroma, it is probable that the enzymatic degradation of PRENCSO is the main cause of that aroma. Consequently, Leucocoryne cultivars should be selected in species and hybrids that lack the ability to synthesise PRENCSO.

A novel alliinase from onion roots. Biochemical characterization and cDNA cloning

We have purified a novel alliinase (EC 4.4.1.4) from roots of onion (Allium cepa L.). Two isoforms with alliinase activity (I and II) were separated by concanavalin A-Sepharose and had molecular masses of 52.7 (I) and 50.5 (II) kD on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 51 (I) and 57.5 (II) kD by gel filtration fast-protein liquid chromatography. Isoform I had an isoelectric point of 9.3, while isoform II had isoelectric points of 7.6, 7.9, 8.1, and 8.3. The isoforms differed in their glycosylation. Both contained xylose/fucose containing complex-type N-linked glycans, and isoform II also contained terminal mannose structures. Both isoforms had activity with S-alk(en)yl-L-cysteine sulfoxides. Unlike other allium alliinases, A. cepa root isoforms had cystine lyase activity. We cloned a gene from A. cepa root cDNA and show that it codes for A. cepa root alliinase protein. Homology to other reported allium alliinase genes is 50%. The gene coded for a protein of mass 51.2 kD, with two regions of deduced amino acid sequence identical to a 25- and a 40-amino acid region, as determined experimentally. The A. cepa root alliinase cDNA was expressed mainly in A. cepa roots. The structure and function of the alliinase gene family is discussed.

Complications with the use of carfentanil citrate and xylazine hydrochloride to immobilize domestic horses

Carfentanil citrate, the only opioid approved in the United States for immobilizing large exotic animals, increasingly has been used to chemically restrain exotic horses, such as Prezwalski's horses (Equus przewalskii) and wild horses (E caballus). Because carfentanil's duration of action is long and renarcotization may develop 2 to 24 hours after administration of antagonists, a study was designed to compare the physiologic effects of opioid antagonists, using domestic horses chemically restrained with xylazine hydrochloride and carfentanil. The study was terminated after the initial 3 horses developed severe tachycardia and hypertension, which resulted in the death of 1 horse from pulmonary edema. Although it was possible that the clinical findings in these horses may have resulted from use of an inadequate dosage of carfentanil or xylazine, or both, analysis of the results more likely indicated that domestic and exotic horses may respond differently to carfentanil, and domestic horses may not be a good model for use in studies of carfentanil.

Subclinical avian malaria infections in African black-footed penguins (Spheniscus demersus) and induction of parasite recrudescence

The subclinical and clinical Plasmodium elongatum and Plasmodium relictum infections of captive-reared African black-footed penguins (Spheniscus demersus) were evaluated in nine adult and 29 juvenile penguins in the Baltimore Zoo (Maryland, USA) during summer 1988 and winter 1989. Two diagnostic methods were used: Giemsa-stained thin blood films, and subinoculation of penguin blood into 1-day-old Peking ducklings. Chloroquine and primaquine treatment was applied to all parasitemic juvenile penguins. Twenty-nine parasite-free, juvenile penguins were monitored for parasitemia by Giemsa-stained thin blood films every two weeks for 26 weeks of their first outdoor exposure. Eighteen of 29 penguins experienced naturally acquired malaria; 14 were infected with P. elongatum, three with P. relictum, and one bird had a mixed P. relictum and P. elongatum infection. Eleven of 18 juveniles became parasitemic again after chloroquine and primaquine treatments. Based on Giemsa-stained thin blood smears and subinoculation of penguin blood into 1-day-old ducklings, performed in a mosquito-free environment in winter, nine adult penguins had no evidence of Plasmodium spp. infection. After dexmethasone-induced immunosuppression, four of six of these nonparasitemic adult penguins were found to be infected with P. relictum by the blood inoculation method.

Maternal antibodies against Plasmodium spp. in African black-footed penguin (Spheniscus demersus) chicks

Anti-Plasmodium spp. antibody titers of mating pairs of adult, captive-reared, African black-footed penguins (Spheniscus demersus) and their chicks were determined using the enzyme-linked-immunosorbent assay (ELISA). Two Plasmodium falciparum antigens were used for the ELISA: R32tet32 (sporozoite antigen), and crude red blood cell extract (CRBCE). Eighteen chicks were bled weekly for ten weeks starting with their day of hatching. The yolk sacs of two penguin eggs were biopsed for ELISA-detectable maternal antibodies (MAB). None of the 28 adult penguins were parasitemic by Giemsa-stained thin blood smear; however, all had anti-Plasmodium spp. immunoglobulins reacting with P. falciparum antigens. All 18 newly hatched chicks had anti-Plasmodium spp. MAB while housed in a mosquito-free environment. The level of MAB in the newly hatched chicks was correlated significantly (P < 0.001) with antibody level detected in their female parents (R32tet32: r = 0.87, CRBCE: r = 0.89). No correlation was found between antibody titers of the newly hatched chicks and their male parents. The level of maternal-fetal antibodies was regressed significantly (P < 0.001) over the 10-week period. Penguin chicks over 10 weeks of age had no anti-Plasmodium spp. MAB. Egg-yolk samples had significantly (P < 0.03) higher MAB titers than female parents that laid these eggs.

Hematologic characteristics of avian malaria cases in African black-footed penguins (Spheniscus demersus) during the first outdoor exposure season

Twenty-nine juvenile, captive-reared African black-footed penguins (Spheniscus demersus) were hematologically monitored every 2 wk over the period of 24 wk during their first outdoor exposure. Blood samples taken from the penguins were screened for 12 blood evaluation parameters. Parasitemic penguins were medically treated. Eighteen birds (62.1%) experienced naturally acquired malaria and 11 birds (37.9%) remained nonparasitemic. A total of 32 avian malaria episodes were noted; 25 (78.1%) were identified as Plasmodium elongatum, 5 (15.6%) as Plasmodium relictum, and 2 (6.3%) as Plasmodium spp. One P. elongatum (3.4%) and 3 P. relictum (10.3%) infections were fatal. All deaths occurred during the first episode of parasitemia. Gross lesions of the birds that died included hepatomegaly and splenomegaly. Interstitial pneumonia with schizonts was observed on histological examinations. The range, mean, and SD of 12 hematological parameters were determined for nonparasitemic and parasitemic penguins. Differences between these groups in total white blood cell (WBC) counts and relative lymphocytosis (LYMPHS) were not significant. The combined classes of total WBC counts (> 20.0 x 10(3)/microliters) and LYMPHS (> 60.0%) are not indicative of avian malaria infection in African penguins. No correlations were found between changes in the values of blood parameters with season or age of penguins. Treatment of parasitemic birds significantly reduced expected mortality from 50.0% to 13.8%.

An ELISA for detecting anti-Plasmodium spp. antibodies in African black-footed penguins (Spheniscus demersus)

An enzyme-linked immunosorbent assay (ELISA) utilizing 3 Plasmodium falciparum antigens, R32tet32, P.F.R27, and crude red blood cell extract, was developed for the detection of circulating anti-Plasmodium relictum or anti-Plasmodium elongatum antibodies in sera from naturally infected adult African black-footed penguins (Spheniscus demersus) at The Baltimore Zoo, Maryland. A concentration of 2.0 micrograms/ml of each antigen was optimal in terms of specificity, sensitivity, and test speed. It was possible to detect anti-Plasmodium spp. antibodies at a dilution of 10(-4.11). Low absorbance values (less than 0.050) of nonspecific background were observed. The binding efficacy of anti-penguin IgG coupled to alkaline phosphatase to antibodies in the penguin sera was significantly higher than the binding efficacy of anti-chicken IgG. All penguins, bled in the winter time, in controlled mosquito-free conditions had anti-Plasmodium spp. antibodies reactive with P. falciparum antigens. The penguins showed age-dependent variation in antibody levels. There was a decrease in antibody titration units that was significantly correlated with the number of outdoor exposure years experienced by the birds, despite the season-comparable epizootiologic conditions in their summer open-air habitat. We concluded that the decrease of anti-malarial antibodies could be explained by an antibody-mediated equilibrium of immunity in naturally immunized birds harboring endothelial-stage parasites. The ELISA described is sensitive, and it requires a minimal amount of equipment to collect the blood samples. The assay can be used for detecting and monitoring levels of anti-Plasmodium spp. antibodies in selected groups of penguins.

Effects of motor activity on children's intentional and incidental memory for spatial locations

Kindergartners (means = 57) and third graders (means = 8-7) encountered a large model town in 1 of 3 conditions of motor involvement with the environment: standing, riding, or walking. Half the children in each motor condition were instructed to remember the location of the buildings (international memory), while the remaining children were not given specific memory instructions (incidental memory). Only the kindergartners' accuracy increased as a function of the amount of motor activity. There was no difference between intentional and incidental memory conditions. It was concluded that: (1) Kindergartners depend on motor activity more than third graders to learn about the location of objects in an unfamiliar environment; and (2) the complexity of the spatial task was primarily responsible for equivalent performance in the intentional and incidental memory conditions.