CD151 Maintains Endolysosomal Protein Quality to Inhibit Vascular Inflammation

BACKGROUND

Tetraspanin CD151 is highly expressed in endothelia and reinforces cell adhesion, but its role in vascular inflammation remains largely unknown.

METHODS

In vitro molecular and cellular biological analyses on genetically modified endothelial cells, in vivo vascular biological analyses on genetically engineered mouse models, and in silico systems biology and bioinformatics analyses on CD151-related events.

RESULTS

Endothelial ablation of Cd151 leads to pulmonary and cardiac inflammation, severe sepsis, and perilous COVID-19, and endothelial CD151 becomes downregulated in inflammation. Mechanistically, CD151 restrains endothelial release of proinflammatory molecules for less leukocyte infiltration. At the subcellular level, CD151 determines the integrity of multivesicular bodies/lysosomes and confines the production of exosomes that carry cytokines such as ANGPT2 (angiopoietin-2) and proteases such as cathepsin-D. At the molecular level, CD151 docks VCP (valosin-containing protein)/p97, which controls protein quality via mediating deubiquitination for proteolytic degradation, onto endolysosomes to facilitate VCP/p97 function. At the endolysosome membrane, CD151 links VCP/p97 to (1) IFITM3 (interferon-induced transmembrane protein 3), which regulates multivesicular body functions, to restrain IFITM3-mediated exosomal sorting, and (2) V-ATPase, which dictates endolysosome pH, to support functional assembly of V-ATPase.

CONCLUSIONS

Distinct from its canonical function in strengthening cell adhesion at cell surface, CD151 maintains endolysosome function by sustaining VCP/p97-mediated protein unfolding and turnover. By supporting protein quality control and protein degradation, CD151 prevents proteins from (1) buildup in endolysosomes and (2) discharge through exosomes, to limit vascular inflammation. Also, our study conceptualizes that balance between degradation and discharge of proteins in endothelial cells determines vascular information. Thus, the IFITM3/V-ATPase-tetraspanin-VCP/p97 complexes on endolysosome, as a protein quality control and inflammation-inhibitory machinery, could be beneficial for therapeutic intervention against vascular inflammation.

N-dihydrogalactochitosan serves as an effective mucosal adjuvant for intranasal vaccine in combination with recombinant viral proteins against respiratory infection

Mucosal vaccinations for respiratory pathogens provide effective protection as they stimulate localized cellular and humoral immunities at the site of infection. Currently, the major limitation of intranasal vaccination is using effective adjuvants capable of withstanding the harsh environment imposed by the mucosa. Herein, we describe the efficacy of using a unique biopolymer, N-dihydrogalactochitosan (GC), as a nasal mucosal vaccine adjuvant against respiratory infections. Specifically, we mixed GC with recombinant SARS-CoV-2 trimeric spike (S) and nucleocapsid (NC) proteins to intranasally vaccinate K18-hACE2 transgenic mice, in comparison with Addavax (AV), an MF-59 equivalent. In contrast to AV, intranasal application of GC induces a robust, systemic antigen-specific antibody response and increases the number of T cells in the cervical lymph nodes. Moreover, GC+S+NC-vaccinated animals were largely resistant to the lethal SARS-CoV-2 challenge and experienced drastically reduced morbidity and mortality, with animal weights and behavior returning to normal 22 days post-infection. In contrast, animals intranasally vaccinated with AV+S+NC experienced severe weight loss, mortality, and respiratory distress, with none surviving beyond 6 days post-infection. Our findings demonstrate that GC can serve as a potent mucosal vaccine adjuvant against SARS-CoV-2 and potentially other respiratory viruses. STATEMENT OF SIGNIFICANCE: We demonstrated that a unique biopolymer, N-dihydrogalactochitosan (GC), was an effective nasal mucosal vaccine adjuvant against respiratory infections. Specifically, we mixed GC with recombinant SARS-CoV-2 trimeric spike (S) and nucleocapsid (NC) proteins to intranasally vaccinate K18-hACE2 transgenic mice, in comparison with Addavax (AV). In contrast to AV, GC induces a robust, systemic antigen-specific antibody response and increases the number of T cells in the cervical lymph nodes. About 90 % of the GC+S+NC-vaccinated animals survived the lethal SARS-CoV-2 challenge and remained healthy 22 days post-infection, while the AV+S+NC-vaccinated animals experienced severe weight loss and respiratory distress, and all died within 6 days post-infection. Our findings demonstrate that GC is a potent mucosal vaccine adjuvant against SARS-CoV-2 and potentially other respiratory viruses.

Single-cell transcriptomics reveals that tumor-infiltrating natural killer cells are activated by localized ablative immunotherapy and share anti-tumor signatures induced by immune checkpoint inhibitors

Rationale

Natural killer (NK) cells provide protective anti-cancer immunity. However, the cancer therapy induced activation gene signatures and pathways in NK cells remain unclear.

Methods

We applied a novel localized ablative immunotherapy (LAIT) by synergizing photothermal therapy (PTT) with intra-tumor delivering of the immunostimulant N-dihydrogalactochitosan (GC), to treat breast cancer using a mammary tumor virus-polyoma middle tumor-antigen (MMTV-PyMT) mouse model. We performed single-cell RNA sequencing (scRNAseq) analysis to unveil the cellular heterogeneity and compare the transcriptional alterations induced by PTT, GC, and LAIT in NK cells within the tumor microenvironment (TME).

Results

ScRNAseq showed that NK subtypes, including cycling, activated, interferon-stimulated, and cytotoxic NK cells. Trajectory analysis revealed a route toward activation and cytotoxicity following pseudotime progression. Both GC and LAIT elevated gene expression associated with NK cell activation, cytolytic effectors, activating receptors, IFN pathway components, and cytokines/chemokines in NK subtypes. Single-cell transcriptomics analysis using immune checkpoint inhibitor (ICI)-treated animal and human samples revealed that ICI-induced NK activation and cytotoxicity across several cancer types. Furthermore, ICI-induced NK gene signatures were also induced by LAIT treatment. We also discovered that several types of cancer patients had significantly longer overall survival when they had higher expression of genes in NK cells that were also specifically upregulated by LAIT.

Conclusion

Our findings show for the first time that LAIT activates cytotoxicity in NK cells and the upregulated genes positively correlate with beneficial clinical outcomes for cancer patients. More importantly, our results further establish the correlation between the effects of LAIT and ICI on NK cells, hence expanding our understanding of mechanism of LAIT in remodeling TME and shedding light on the potentials of NK cell activation and anti-tumor cytotoxic functions in clinical applications.

The Isolation and In Vitro Differentiation of Primary Fetal Baboon Tracheal Epithelial Cells for the Study of SARS-CoV-2 Host-Virus Interactions

The mucociliary airway epithelium lines the human airways and is the primary site of host-environmental interactions in the lung. Following virus infection, airway epithelial cells initiate an innate immune response to suppress virus replication. Therefore, defining the virus-host interactions of the mucociliary airway epithelium is critical for understanding the mechanisms that regulate virus infection, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Non-human primates (NHP) are closely related to humans and provide a model to study human disease. However, ethical considerations and high costs can restrict the use of in vivo NHP models. Therefore, there is a need to develop in vitro NHP models of human respiratory virus infection that would allow for rapidly characterizing virus tropism and the suitability of specific NHP species to model human infection. Using the olive baboon (Papio anubis), we have developed methodologies for the isolation, in vitro expansion, cryopreservation, and mucociliary differentiation of primary fetal baboon tracheal epithelial cells (FBTECs). Furthermore, we demonstrate that in vitro differentiated FBTECs are permissive to SARS-CoV-2 infection and produce a potent host innate-immune response. In summary, we have developed an in vitro NHP model that provides a platform for the study of SARS-CoV-2 infection and other human respiratory viruses.

Antigen Discovery for Next-Generation Pertussis Vaccines Using Immunoproteomics and Transposon-Directed Insertion Sequencing

BACKGROUND

Despite high vaccination rates, the United States has experienced a resurgence in reported cases of pertussis after switching to the acellular pertussis vaccine, indicating a need for improved vaccines that enhance infection control.

METHODS

Bordetella pertussis antigens recognized by convalescent-baboon serum and nasopharyngeal wash were identified by immunoproteomics and their subcellular localization predicted. Genes essential or important for persistence in the baboon airway were identified by transposon-directed insertion-site sequencing (TraDIS) analysis.

RESULTS

In total, 314 B. pertussis antigens were identified by convalescent baboon serum and 748 by nasopharyngeal wash. Thirteen antigens were identified as immunogenic in baboons, essential for persistence in the airway by TraDIS, and membrane-localized: BP0840 (OmpP), Pal, OmpA2, BP1485, BamA, Pcp, MlaA, YfgL, BP2197, BP1569, MlaD, ComL, and BP0183.

CONCLUSIONS

The B. pertussis antigens identified as immunogenic, essential for persistence in the airway, and membrane-localized warrant further investigation for inclusion in vaccines designed to reduce or prevent carriage of bacteria in the airway of vaccinated individuals.

Early and mid-gestation Zika virus (ZIKV) infection in the olive baboon (Papio anubis) leads to fetal CNS pathology by term gestation

Zika virus (ZIKV) infection in pregnancy can produce catastrophic teratogenic damage to the developing fetus including microcephaly and congenital Zika syndrome (CZS). We previously described fetal CNS pathology occurring by three weeks post-ZIKV inoculation in Olive baboons at mid-gestation, including neuroinflammation, loss of radial glia (RG), RG fibers, neuroprogenitor cells (NPCs) resulting in disrupted NPC migration. In the present study, we explored fetal brain pathologies at term gestation resulting from ZIKV exposure during either first or second trimester in the Olive baboon. In all dams, vRNA in whole blood resolved after 7 days post inoculation (dpi). One first trimester infected dam aborted at 5 dpi. All dams developed IgM and IgG response to ZIKV with ZIKV IgG detected in fetal serum. Placental pathology and inflammation were observed including disruption of syncytiotrophoblast layers, delayed villous maturation, partially or fully thrombosed vessels, calcium mineralization and fibrin deposits. In the uterus, ZIKV was detected in ¾ first trimester but not in second trimester infected dams. While ZIKV was not detected in any fetal tissue at term, all fetuses exhibited varying degrees of neuropathology. Fetal brains from ZIKV inoculated dams exhibited a range of gross brain pathologies including irregularities of the major gyri and sulci of the cerebral cortex and cerebellar pathology. Frontal cortices of ZIKV fetuses showed a general disorganization of the six-layered cortex with degree of disorganization varying among the fetuses from the two groups. Frontal cortices from ZIKV inoculation in the first but not second trimester exhibited increased microglia, and in both trimester ZIKV inoculation, increased astrocyte numbers (white matter). In the cerebellum, increased microglia were observed in fetuses from both first and second trimester inoculation. In first trimester ZIKV inoculation, decreased oligodendrocyte precursor cell populations were observed in fetal cerebellar white matter. In general, our observations are in accordance with those described in human ZIKV infected fetuses.

Western diet-induced shifts in the maternal microbiome are associated with altered microRNA expression in baboon placenta and fetal liver

Maternal consumption of a high-fat, Western-style diet (WD) disrupts the maternal/infant microbiome and contributes to developmental programming of the immune system and nonalcoholic fatty liver disease (NAFLD) in the offspring. Epigenetic changes, including non-coding miRNAs in the fetus and/or placenta may also underlie this risk. We previously showed that obese nonhuman primates fed a WD during pregnancy results in the loss of beneficial maternal gut microbes and dysregulation of cellular metabolism and mitochondrial dysfunction in the fetal liver, leading to a perturbed postnatal immune response with accelerated NAFLD in juvenile offspring. Here, we investigated associations between WD-induced maternal metabolic and microbiome changes, in the absence of obesity, and miRNA and gene expression changes in the placenta and fetal liver. After ~8-11 months of WD feeding, dams were similar in body weight but exhibited mild, systemic inflammation (elevated CRP and neutrophil count) and dyslipidemia (increased triglycerides and cholesterol) compared with dams fed a control diet. The maternal gut microbiome was mainly comprised of Lactobacillales and Clostridiales, with significantly decreased alpha diversity (P = 0.0163) in WD-fed dams but no community-wide differences (P = 0.26). At 0.9 gestation, mRNA expression of IL6 and TNF in maternal WD (mWD) exposed placentas trended higher, while increased triglycerides, expression of pro-inflammatory CCR2, and histological evidence for fibrosis were found in mWD-exposed fetal livers. In the mWD-exposed fetus, hepatic expression levels of miR-204-5p and miR-145-3p were significantly downregulated, whereas in mWD-exposed placentas, miR-182-5p and miR-183-5p were significantly decreased. Notably, miR-1285-3p expression in the liver and miR-183-5p in the placenta were significantly associated with inflammation and lipid synthesis pathway genes, respectively. Blautia and Ruminococcus were significantly associated with miR-122-5p in liver, while Coriobacteriaceae and Prevotellaceae were strongly associated with miR-1285-3p in the placenta; both miRNAs are implicated in pathways mediating postnatal growth and obesity. Our findings demonstrate that mWD shifts the maternal microbiome, lipid metabolism, and inflammation prior to obesity and are associated with epigenetic changes in the placenta and fetal liver. These changes may underlie inflammation, oxidative stress, and fibrosis patterns that drive NAFLD and metabolic disease risk in the next generation.

Characterization of the SARS-CoV-2 Host Response in Primary Human Airway Epithelial Cells from Aged Individuals

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19), a global pandemic characterized by an exaggerated immune response and respiratory illness. Age (>60 years) is a significant risk factor for developing severe COVID-19. To better understand the host response of the aged airway epithelium to SARS-CoV-2 infection, we performed an in vitro study using primary human bronchial epithelial cells from donors >67 years of age differentiated on an air–liquid interface culture. We demonstrate that SARS-CoV-2 infection leads to early induction of a proinflammatory response and a delayed interferon response. In addition, we observed changes in the genes and pathways associated with cell death and senescence throughout infection. In summary, our study provides new and important insights into the temporal kinetics of the airway epithelial innate immune response to SARS-CoV-2 in older individuals.

L-SIGN is a receptor on liver sinusoidal endothelial cells for SARS-CoV-2 virus

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a pandemic. Severe disease is associated with dysfunction of multiple organs, but some infected cells do not express ACE2, the canonical entry receptor for SARS-CoV-2. Here, we report that the C-type lectin receptor L-SIGN interacted in a Ca²⁺-dependent manner with high-mannose–type N-glycans on the SARS-CoV-2 spike protein. We found that L-SIGN was highly expressed on human liver sinusoidal endothelial cells (LSECs) and lymph node lymphatic endothelial cells but not on blood endothelial cells. Using high-resolution confocal microscopy imaging, we detected SARS-CoV-2 viral proteins within the LSECs from liver autopsy samples from patients with COVID-19. We found that both pseudo-typed virus enveloped with SARS-CoV-2 spike protein and authentic SARS-CoV-2 virus infected L-SIGN–expressing cells relative to control cells. Moreover, blocking L-SIGN function reduced CoV-2–type infection. These results indicate that L-SIGN is a receptor for SARS-CoV-2 infection. LSECs are major sources of the clotting factors vWF and factor VIII (FVIII). LSECs from liver autopsy samples from patients with COVID-19 expressed substantially higher levels of vWF and FVIII than LSECs from uninfected liver samples. Our data demonstrate that L-SIGN is an endothelial cell receptor for SARS-CoV-2 that may contribute to COVID-19–associated coagulopathy.

Intranasal and intrapulmonary vaccination with an M protein-deficient respiratory syncytial virus (RSV) vaccine improves clinical signs and reduces viral replication in infant baboons after an RSV challenge infection

Respiratory syncytial virus (RSV) is the major viral respiratory pathogen for human infants and children. Despite a severe global burden incurred by annual RSV epidemics, there is no licensed RSV vaccine. We have developed an RSV vaccine from a human RSV strain from which the gene for the viral M protein has been deleted ("Mnull RSV"). RSV infects airway cells and produces each of its proteins. The M protein is responsible for reassembling the various other synthesized viral proteins into new, intact virus. In the absence of the M protein, therefore, reassembly does not occur, and the Mnull RSV does not replicate. We vaccinated 2-week old infant baboons with Mnull RSV either intranasally (IN) or directly into the lung (intratracheal, or IT), then infected these animals by inoculating human RSV directly into the lung. IN vaccination induced inconsistent serum RSV neutralizing antibody (NA) responses, but provided moderate reductions in respiratory rates, overall signs of illness and viral replication in bronchoalveolar lavage (BAL) fluid following infection. Intratracheal vaccination induced much stronger RSV NA responses, which persisted for at least 4-6 months. Following RSV infection, animals vaccinated by the IT route had much greater reductions in tachypnea and work of breathing than animals vaccinated IN, and had undetectable amounts of virus in BAL fluids. These results support the further development of IT Mnull RSV vaccination to reduce the impact of RSV infection in humans.

The Impact of Advanced Age on Vaccine-Induced Tissue Immune Recall Responses

Infectious diseases account for one-third of deaths in individuals over the age of 65. Vaccines are a primary tool to combat infection, yet they are less effective in the aged population. Many have focused on vaccine-induced peripheral blood responses in old age; however, work from our lab demonstrates that immune responses to vaccination and infection in the periphery and local infection site (tissue) differ. To improve health outcomes in our aged population, we must study both systemic and tissue vaccine responses. We do so using a model of Mycobacterium bovis BCG vaccination and subsequent tuberculin skin test (TST) eight weeks after vaccination in adult and aged baboons. Vaccination generates BCG-specific immune cells that are recruited to the skin upon TST challenge, which we can study in skin biopsies reflecting tissue-specific responses. Three days or one week after TST we examine BCG-specific responses in skin biopsies. We also determine BCG-induced responses in the blood to compare tissue and systemic responses. We find increased oxidation and decreased production of immune proteins in aged baboon skin at the site of TST challenge, despite no alterations in antigen-specific peripheral blood mononuclear cell (PBMC) responses between age groups. Interestingly, cell migration assays show increased migration of PBMCs from aged BCG-vaccinated baboons, reinforcing the notion that systemic responses are not altered and that study of the tissue environment is important to understand responses to antigenic challenge with older age.

Local immune responses to tuberculin skin challenge in Mycobacterium bovis BCG-vaccinated baboons: a pilot study of younger and older animals

Individuals over the age of 65 are highly susceptible to infectious diseases, which account for one-third of deaths in this age group. Vaccines are a primary tool to combat infection, yet they are less effective in the elderly population. While many groups have aimed to address this problem by studying vaccine-induced peripheral blood responses in the elderly, work from our lab and others demonstrate that immune responses to vaccination and infectious challenge may differ between tissue sites and the periphery. In this pilot study, we established an in vivo delayed-type hypersensitivity model of Mycobacterium bovis BCG vaccination and tuberculin skin test in two adult and two aged baboons. Vaccination generates BCG-specific immune cells that are recruited to the skin upon tuberculin challenge. We tested short term recall responses (8 weeks post-vaccination) and long term recall responses (25 weeks post-vaccination) by performing skin punch biopsies around the site of tuberculin injection. In short term recall responses, we found increased oxidation and decreased production of immune proteins in aged baboon skin at the site of TST challenge, in comparison to adult skin. Differences between adult and aged animals normalized in the long term response to tuberculin. In vitro, aged peripheral blood mononuclear cells had increased migration and functional responses to antigen-specific stimulation, suggesting that age-related changes in the tissue in vivo impairs aged immune recall responses to antigenic challenge. These findings highlight the impact of age-associated changes in the local tissue environment in memory recall responses, which may be more broadly applied to the study of other tissues. Moreover, these findings should be considered in future studies aimed at understanding and improving aging immune responses to vaccination and tissue challenge.

Fifteen Years of Sm-p80-Based Vaccine Trials in Nonhuman Primates: Antibodies From Vaccinated Baboons Confer Protection in vivo and in vitro From Schistosoma mansoni and Identification of Putative Correlative Markers of Protection

Recent advances in systems biology have shifted vaccine development from a largely trial-and-error approach to an approach that promote rational design through the search for immune signatures and predictive correlates of protection. These advances will doubtlessly accelerate the development of a vaccine for schistosomiasis, a neglected tropical disease that currently affects over 250 million people. For over 15 years and with contributions of over 120 people, we have endeavored to test and optimize Sm-p80-based vaccines in the non-human primate model of schistosomiasis. Using RNA-sequencing on eight different Sm-p80-based vaccine strategies, we sought to elucidate immune signatures correlated with experimental protective efficacy. Furthermore, we aimed to explore the role of antibodies through in vivo passive transfer of IgG obtained from immunized baboons and in vitro killing of schistosomula using Sm-p80-specific antibodies. We report that passive transfer of IgG from Sm-p80-immunized baboons led to significant worm burden reduction, egg reduction in liver, and reduced egg hatching percentages from tissues in mice compared to controls. In addition, we observed that sera from Sm-p80-immunized baboons were able to kill a significant percent of schistosomula and that this effect was complement-dependent. While we did not find a universal signature of immunity, the large datasets generated by this study will serve as a substantial resource for further efforts to develop vaccine or therapeutics for schistosomiasis.

The role of old age on Mycobacterium bovis BCG vaccine-induced tissue immunity

Infections account for one-third of deaths in elderly individuals. Vaccines are a primary tool to combat infection, yet they are less effective in the elderly population. While many groups have aimed to address this problem by studying vaccine-induced peripheral blood responses in the elderly, work from our lab demonstrates that immune responses to vaccination and infectious challenge differ between tissue sites and the periphery. To improve health outcomes in our aged population, we must study vaccine-responses in both the periphery and the local infection site (the tissue). We study this through a delayed-type hypersensitivity model of Mycobacterium bovis BCG vaccination and subsequent tuberculin skin test (TST) eight weeks after vaccination in adult and elderly baboons. Vaccination generates BCG-specific immune cells that are recruited to the skin upon TST challenge which we can study in skin biopsies reflecting tissue specific responses. Three days or one week after TST we examine BCG-specific memory responses in the skin biopsies. We also determine BCG-induced responses in the blood to compare tissue and systemic responses. We find increased oxidation and decreased production of cytokines, chemokines and growth factors in aged baboon skin at the site of TST challenge, despite no alteration in vaccine-induced peripheral blood responses between age groups. Based on these findings, we anticipate that alterations in the skin of aged BCG-vaccinated baboons will hinder T cell migration to and function in the tissue, thus decreasing vaccine-induced tissue immunity.

Chronic whipworm infection exacerbates Schistosoma mansoni egg-induced hepatopathology in non-human primates

BACKGROUND

Schistosomiasis continues to inflict significant morbidity and mortality in the tropical and subtropical regions of the world. The disease endemicity overlaps with the transmission of other parasitic diseases. Despite the ubiquity of polyparasitism in tropical regions, particularly in rural communities, little is known about the impact of multiple helminth infections on disease progression. In this pilot study, we describe the influence of chronic Trichuris trichiura infection on Schistosoma mansoni egg-induced hepatopathology in infected baboons.

METHODS

Baboons with or without underlying whipworm infection were challenged with S. mansoni cercariae to establish schistosomiasis. Adult S. mansoni worms were recovered by perfusion and enumerated, hepatic granulomas were quantified via light microscopy, and transcriptional profiling of tissues were completed using RNA sequencing technologies.

RESULTS

Co-infection with both S. mansoni and T. trichiura resulted in higher female schistosome worm burden and significantly larger liver granuloma sizes. Systems biology analyses of peripheral blood mononuclear cells (PBMC) revealed pathways associated with increased liver damage in co-infected baboons.

CONCLUSIONS

Underlying chronic whipworm infection intensified schistosome egg-induced liver pathology in infected baboons. RNA-Seq analysis provided insight into pathways associated with increased liver damage, corroborating histological findings.

In vitro and In vivo Susceptibility of Baboons (Papio sp.) to Infection with and Apparent Antibody Reactivity to Simian Betaretrovirus (SRV)

Despite the lack of confirmed reports of an exogenous Simian betaretrovirus (SRV) isolated from baboons (Papio sp.), reports of simian endogenous gammaretrovirus (SERV) in baboons with complete genomes suggest that such viruses may be potentially infectious. In addition, serologic tests have repeatedly demonstrated antibody reactivity to SRV in baboons from multiple colonies. These findings complicate the management and use of such animals for research. To provide further insight into this situation, we performed in vitro and in vivo studies to determine if baboons are or can be infected with SRV. In our initial experiment, we were not able to isolate SRV from 6 seropositive or sero-indeterminate baboons by coculturing their peripheral blood mononuclear cells (PBMC) with macaque PBMC or permissive cell lines. In a subsequent experiment, we found that baboon PBMC infected in vitro with high dose SRV were permissive to virus replication. To test in vivo infectibil- ity, groups of naive baboons were infused intravenously with either (i) the same SRV tissue culture virus stocks used for the in vitro studies, (ii) SRV antibody positive and PCR positive macaque blood, (iii) SRV antibody positive or indeterminate, but PCR negative baboon blood, or (iv) SRV antibody and PCR negative baboon blood. Sustained SRV infection, as defined by reproducible PCR detection and/or antibody seroconversion, was confirmed in 2 of 3 baboons receiving tissue culture virus but not in any recipients of transfused blood from seropositive macaques or baboons. In conclusion, the data indicate that even though baboon cells can be infected experimentally with high doses of tissue culture grown SRV, baboons that are repeatedly SRV antibody positive and PCR negative are unlikely to be infected with exogenous SRV and thus are unlikely to transmit a virus that would threaten the SPF status of captive baboon colonies.

Neutralization of pertussis toxin by a single antibody prevents clinical pertussis in neonatal baboons

Pertussis continues to cause considerable infant mortality world-wide, which could be addressed in part by passive immunization strategies. Antibody hu1B7 is a candidate therapeutic that potently neutralizes pertussis toxin in vitro, prevents leukocytosis in mice and treats established disease in weanling baboons as part of an antibody cocktail. Here, we evaluated the potential for hu1B7 and an extended half-life hu1B7 variant to prevent death, leukocytosis and other clinical symptoms in a newborn baboon model that mimics many aspects of human disease. We administered a single antibody dose to newborn baboons five weeks prior to experimental infection. While all animals were heavily colonized with Bordetella pertussis, prophylaxed animals showed significantly greater survival (P < 0.005), delayed and suppressed leukocytosis (P < 0.01) and enhanced clinical outcomes, including coughing (P < 0.01), as compared to controls. Together, this work demonstrates that a single neutralizing anti-PTx antibody is sufficient to prevent clinical pertussis symptoms.

Maternal immunization with RSV fusion glycoprotein vaccine and substantial protection of neonatal baboons against respiratory syncytial virus pulmonary challenge

Globally, human respiratory syncytial virus (RSV) is a major cause of severe lower respiratory infection in infants and young children. There are no licensed vaccines despite the high worldwide disease burden. RSV fusion (F) glycoprotein vaccine is the most advanced candidate for maternal immunization. In this report, a baboon maternal immunization model was used to assess the immunogenicity and protection of infants against pulmonary challenge with human RSV/A. Vaccination in the third trimester produced high anti-RSV F IgG titers and virus-neutralizing antibodies. Infants born to immunized females had high levels of serum RSV antibodies that were comparable to maternal levels at birth and persisted for over 50 days with a half-life of 14-24 days. Furthermore, infants from immunized females and challenged with RSV/A were healthy, developed less severe disease, and had only mild pulmonary inflammatory changes whereas infants born to non-vaccinated females developed more severe disease with marked to moderate interstitial pneumonia, pulmonary edema, and bronchiolar obstruction. These results support the further development of the RSV F vaccine for maternal immunization.

Zika virus infection at mid-gestation results in fetal cerebral cortical injury and fetal death in the olive baboon

Zika virus (ZIKV) infection during pregnancy in humans is associated with an increased incidence of congenital anomalies including microcephaly as well as fetal death and miscarriage and collectively has been referred to as Congenital Zika Syndrome (CZS). Animal models for ZIKV infection in pregnancy have been developed including mice and non-human primates (NHPs). In macaques, fetal CZS outcomes from maternal ZIKV infection range from none to significant. In the present study we develop the olive baboon (Papio anubis), as a model for vertical transfer of ZIKV during pregnancy. Four mid-gestation, timed-pregnant baboons were inoculated with the French Polynesian ZIKV isolate (10⁴ ffu). This study specifically focused on the acute phase of vertical transfer. Dams were terminated at 7 days post infection (dpi; n = 1), 14 dpi (n = 2) and 21 dpi (n = 1). All dams exhibited mild to moderate rash and conjunctivitis. Viremia peaked at 5–7 dpi with only one of three dams remaining mildly viremic at 14 dpi. An anti-ZIKV IgM response was observed by 14 dpi in all three dams studied to this stage, and two dams developed a neutralizing IgG response by either 14 dpi or 21 dpi, the latter included transfer of the IgG to the fetus (cord blood). A systemic inflammatory response (increased IL2, IL6, IL7, IL15, IL16) was observed in three of four dams. Vertical transfer of ZIKV to the placenta was observed in three pregnancies (n = 2 at 14 dpi and n = 1 at 21 dpi) and ZIKV was detected in fetal tissues in two pregnancies: one associated with fetal death at ~14 dpi, and the other in a viable fetus at 21 dpi. ZIKV RNA was detected in the fetal cerebral cortex and other tissues of both of these fetuses. In the fetus studied at 21 dpi with vertical transfer of virus to the CNS, the frontal cerebral cortex exhibited notable defects in radial glia, radial glial fibers, disorganized migration of immature neurons to the cortical layers, and signs of pathology in immature oligodendrocytes. In addition, indices of pronounced neuroinflammation were observed including astrogliosis, increased microglia and IL6 expression. Of interest, in one fetus examined at 14 dpi without detection of ZIKV RNA in brain and other fetal tissues, increased neuroinflammation (IL6 and microglia) was observed in the cortex. Although the placenta of the 14 dpi dam with fetal death showed considerable pathology, only minor pathology was noted in the other three placentas. ZIKV was detected immunohistochemically in two placentas (14 dpi) and one placenta at 21 dpi but not at 7 dpi. This is the first study to examine the early events of vertical transfer of ZIKV in a NHP infected at mid-gestation. The baboon thus represents an additional NHP as a model for ZIKV induced brain pathologies to contrast and compare to humans as well as other NHPs.

Zika virus is endemic in the Americas, primarily spread through mosquitos and sexual contact. Zika virus infection during pregnancy in women is associated with a variety of fetal pathologies now referred to as Congenital Zika Syndrome (CZS), with the most severe pathology being fetal microcephaly. Developing model organisms that faithfully recreate Zika infection in humans is critical for future development of treatments and preventions. In our present study, we infected Olive baboons at mid-gestation with Zika virus and studied the acute period of viremia and transfer of Zika virus to the fetus during the first three weeks after infection to better understand the timing and mechanisms of transfer of ZIKV across the placenta, leading to CZS. We observed Zika virus transfer to fetuses resulting in fetal death in one pregnancy and in a second pregnancy, significant damage to the frontal cortex of the fetal brain at a critical period of neurodevelopment in primates. Thus, the baboon provides a promising new non-human primate model to further compare and contrast the consequences of Zika virus infection in pregnancy to humans and other non-human primates.

Translational Model of Zika Virus Disease in Baboons

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus with devastating outcomes seen recently in the Americas due to the association of maternal ZIKV infection with fetal microcephaly and other fetal malformations not previously associated with flavivirus infections. Here, we have developed the olive baboon (Papio anubis) as a nonhuman primate (NHP) translational model for the study of ZIKV pathogenesis and associated disease outcomes to contrast and compare with humans and other major NHPs, such as macaques. Following subcutaneous inoculation of adult male and nonpregnant female baboons, viremia was detected at 3 and 4 days postinfection (dpi) with the concordant presentation of a visible rash and conjunctivitis, similar to human ZIKV infection. Furthermore, virus was detected in the mucosa and cerebrospinal fluid. A robust ZIKV-specific IgM and IgG antibody response was also observed in all the animals. These data show striking similarity between humans and the olive baboon following infection with ZIKV, suggesting our model is a suitable translational NHP model to study ZIKV pathogenesis and potential therapeutics.IMPORTANCE ZIKV was first identified in 1947 in a sentinel rhesus monkey in Uganda and subsequently spread to Southeast Asia. Until 2007, only a small number of cases were reported, and ZIKV infection was relatively minor until the South Pacific and Brazilian outbreaks, where more severe outcomes were reported. Here, we present the baboon as a nonhuman primate model for contrast and comparison with other published animal models of ZIKV, such as the mouse and macaque species. Baboons breed year round and are not currently a primary nonhuman primate species used in biomedical research, making them more readily available for studies other than human immunodeficiency virus studies, which many macaque species are designated for. This, taken together with the similarities baboons have with humans, such as immunology, reproduction, genetics, and size, makes the baboon an attractive NHP model for ZIKV studies in comparison to other nonhuman primates.

Sm-p80-based schistosomiasis vaccine: double-blind preclinical trial in baboons demonstrates comprehensive prophylactic and parasite transmission-blocking efficacy

Schistosomiasis is of public health importance to an estimated one billion people in 79 countries. A vaccine is urgently needed. Here, we report the results of four independent, double-blind studies of an Sm-p80-based vaccine in baboons. The vaccine exhibited potent prophylactic efficacy against transmission of Schistosoma mansoni infection and was associated with significantly less egg-induced pathology, compared with unvaccinated control animals. Specifically, the vaccine resulted in a 93.45% reduction of pathology-producing female worms and significantly resolved the major clinical manifestations of hepatic/intestinal schistosomiasis by reducing the tissue egg-load by 89.95%. A 35-fold decrease in fecal egg excretion in vaccinated animals, combined with an 81.51% reduction in hatching of eggs into the snail-infective stage (miracidia), demonstrates the parasite transmission-blocking potential of the vaccine. Substantially higher Sm-p80 expression in female worms and Sm-p80-specific antibodies in vaccinated baboons appear to play an important role in vaccine-mediated protection. Preliminary analyses of RNA sequencing revealed distinct molecular signatures of vaccine-induced effects in baboon immune effector cells. This study provides comprehensive evidence for the effectiveness of an Sm-p80-based vaccine for schistosomiasis.

Sm-p80-based vaccine trial in baboons: efficacy when mimicking natural conditions of chronic disease, praziquantel therapy, immunization, and Schistosoma mansoni re-encounter

Sm-p80-based vaccine efficacy for Schistosoma mansoni was evaluated in a baboon model of infection and disease. The study was designed to replicate a human vaccine implementation scenario for endemic regions in which vaccine would be administered following drug treatment of infected individuals. In our study, the Sm-p80-based vaccine reduced principal pathology producing hepatic egg burdens by 38.0% and egg load in small and large intestines by 72.2% and 49.4%, respectively, in baboons. Notably, hatching rates of eggs recovered from liver and small and large intestine of vaccinated animals were significantly reduced, by 60.4%, 48.6%, and 82.3%, respectively. Observed reduction in egg maturation/hatching rates was supported by immunofluorescence and confocal microscopy showing unique differences in Sm-p80 expression in worms of both sexes and matured eggs. Vaccinated baboons had a 64.5% reduction in urine schistosome circulating anodic antigen, a parameter that reflects worm numbers/health status in infected hosts. Preliminary analyses of RNA sequencing revealed unique genes and canonical pathways associated with establishment of chronic disease, praziquantel-mediated parasite killing, and Sm-p80-mediated protection in vaccinated baboons. Overall, our study demonstrated efficacy of the Sm-p80 vaccine and provides insight into some of the epistatic interactions associated with protection.

Maternal Vaccination With a Monocomponent Pertussis Toxoid Vaccine Is Sufficient to Protect Infants in a Baboon Model of Whooping Cough

Background

Bordetella pertussis is a human pathogen responsible for serious respiratory illness. The disease is most severe in infants too young to be vaccinated with most hospitalizations and deaths occurring within this age group. The Advisory Committee on Immunization Practices recommended immunization of pregnant women to protect infants from birth until their first vaccination at 6-8 weeks of age. We previously demonstrated that maternal vaccination with licensed acellular pertussis vaccines protected newborn baboons from disease. We hypothesized that protection was due to toxin-neutralizing, maternal anti-pertussis toxin antibodies and predicted that maternal vaccination with a pertussis toxoid (PTx)-only vaccine would protect newborns from disease.

Methods

Infant baboons born to unvaccinated mothers or mothers vaccinated with a PTx-only vaccine were challenged with B. pertussis at 5 weeks of age and followed for infection and signs of disease.

Results

Although all challenged infants were heavily colonized, the infant baboons born to mothers vaccinated with PTx-only vaccine were free from clinical disease following exposure to B. pertussis. In contrast, disease was observed in infants born to unvaccinated mothers.

Conclusions

Our results demonstrated that maternal vaccination with a PTx-only vaccine is sufficient to protect newborn baboons from disease following exposure to pertussis.

Apnea induction for invasive lung function testing in infant olive baboons: Comparison of intravenous propofol versus hyperventilation

BACKGROUND

In various types of pulmonary research, pulmonary function testing (PFT) is performed to quantify the severity of lung disease. Induction of apnea and positive pressure ventilation are required for accurate PFT measurements in non-cooperative subjects. We compared two methods of apnea induction in infant olive baboons (Papio anubis).

METHODS

Pulmonary function testing results were compared during apnea induced by hyperventilation (CO₂ washout) vs. intravenous propofol (1 dose 10 mg/kg). PFT was evaluated using a hot-wire pneumotachometer incorporated within an Avea ventilator in nine 1-month-old baboons.

RESULTS

Propofol induced apnea faster and more reliably. In both groups, PFT values passed the statistical equivalence test and were not significantly different (Student's t-test). There was a trend toward less data variability after propofol administration.

CONCLUSIONS

Intravenous propofol was non-inferior to CO₂ washout for apnea induction in infant olive baboons. Propofol induced apnea faster and more reliably and yielded less variable PFT results.

Live Attenuated Pertussis Vaccine BPZE1 Protects Baboons Against Bordetella pertussis Disease and Infection

Evidence suggests that the resurgence of pertussis in many industrialized countries may result from the failure of current vaccines to prevent nasopharyngeal colonization by Bordetella pertussis, the principal causative agent of whooping cough. Here, we used a baboon model to test the protective potential of the novel, live attenuated pertussis vaccine candidate BPZE1. A single intranasal/intratracheal inoculation of juvenile baboons with BPZE1 resulted in transient nasopharyngeal colonization and induction of immunoglobulin G and immunoglobulin A to all antigens tested, while causing no adverse symptoms or leukocytosis. When BPZE1-vaccinated baboons were challenged with a high dose of a highly virulent B. pertussis isolate, they were fully protected against disease, whereas naive baboons developed illness (with 1 death) and leukocytosis. Total postchallenge nasopharyngeal virulent bacterial burden of vaccinated animals was substantially reduced (0.002%) compared to naive controls, providing promising evidence in nonhuman primates that BPZE1 protects against both pertussis disease and B. pertussis infection.

Maternal Pertussis Vaccination with a Mono-component Pertussis Toxoid Vaccine is Sufficient to Protect Newborns

Bordetella pertussis is a highly infectious human pathogen causing serious illness in infants, children and adults. The first pertussis vaccination is administered at two months of age, therefore, infants under two months of age are most vulnerable to infection. Rising incidence of pertussis resulted in the 2012 recommendation by the Advisory Committee on Immunization Practices (ACIP) to immunize all pregnant women to protect infants from birth until their first vaccination. Using a baboon model, we demonstrated that maternal vaccination with the three or four component acellular pertussis vaccines protected newborn baboons from the disease but not from the colonization. We hypothesized this protection was due to the transfer of maternal anti-PT antibodies to the infant. Therefore we evaluated the protection conferred by maternal vaccination with a pertussis toxoid (PTx) only vaccine. Infant baboons born to mothers vaccinated with the PTx-only vaccine were free from disease and had low WBC counts following exposure to B. pertussis at five weeks of age. In contrast, infants born to unvaccinated mothers experienced severe disease with high WBC counts. Our results demonstrate that vaccination of baboons during pregnancy with a PTx-only vaccine is sufficient to protect newborn baboons from disease following exposure to pertussis. Because pertussis toxin is a secreted protein that can be purified from bacterial supernatants, a single-component vaccine comprised of pertussis toxoid is very likely the most cost-effective acellular pertussis vaccine possible. The development and use of mono-component PTx vaccines may enable the extension of maternal vaccine programs to low and middle income countries.

Prior exposure to Bordetella species as an exclusion criterion in the baboon model of pertussis

The baboon model of Bordetella pertussis infection is the newest and most clinically accurate model of the human disease to date. However, among the 15 experimentally infected baboons in this study, a subset of baboons did not exhibit the expected high bacterial colonization levels or increase in white blood cell count. Moreover, cultures of nasopharyngeal wash samples from several baboons suggested B. bronchiseptica coinfection. Analysis of serum antibodies recognizing filamentous hemagglutinin, pertussis toxin and B. pertussis lipo-oligosaccharide indicated that several baboons had likely been previously exposed to Bordetella species and that prior exposure correlated with partial protection from B. pertussis infection. Notably, all animals with a baseline Fha titer of 5 IU/ml or below exhibited symptoms typical of the model, suggesting this value can be used as inclusion criteria for animals prior to study enrollment. While B. pertussis infection is endemic to human populations and B. bronchiseptica is common in wild small mammals, this study illustrates that baboons can readily harbor both organisms. Awareness of Bordetella species that share antigens capable of generating protective immune responses and tracking of prior exposure to those species is required for successful use of the baboon model of pertussis.

A cocktail of humanized anti-pertussis toxin antibodies limits disease in murine and baboon models of whooping cough

Despite widespread vaccination, pertussis rates are rising in industrialized countries and remain high worldwide. With no specific therapeutics to treat disease, pertussis continues to cause considerable infant morbidity and mortality. The pertussis toxin is a major contributor to disease, responsible for local and systemic effects including leukocytosis and immunosuppression. We humanized two murine monoclonal antibodies that neutralize pertussis toxin and expressed them as human immunoglobulin G1 molecules with no loss of affinity or in vitro neutralization activity. When administered prophylactically to mice as a binary cocktail, antibody treatment completely mitigated the Bordetella pertussis-induced rise in white blood cell counts and decreased bacterial colonization. When administered therapeutically to baboons, antibody-treated, but not untreated control animals, experienced a blunted rise in white blood cell counts and accelerated bacterial clearance rates. These preliminary findings support further investigation into the use of these antibodies to treat human neonatal pertussis in conjunction with antibiotics and supportive care.

Maternal and neonatal vaccination protects newborn baboons from pertussis infection

BACKGROUND

The United States is experiencing a pertussis resurgence that resulted in a 60-year high of 48 000 cases in 2012. The majority of hospitalizations and deaths occur in infants too young to be vaccinated. Neonatal and maternal vaccination have been proposed to protect newborns until the first vaccination, currently recommended at 2 months of age. These interventions result in elevated anti-Bordetella pertussis titers, but there have been no studies demonstrating that these measures confer protection.

METHODS

Baboons were vaccinated with acellular pertussis vaccine at 2 days of age or at 2 and 28 days of age. To model maternal vaccination, adult female baboons primed with acellular pertussis vaccine were boosted in the third trimester of pregnancy. Neonatally vaccinated infants, infants born to vaccinated mothers, and naive infants born to unvaccinated mothers were infected with B. pertussis at 5 weeks of age.

RESULTS

Naive infant baboons developed severe disease when challenged with B. pertussis at 5 weeks of age. Baboons receiving acellular pertussis vaccine and infants born to mothers vaccinated at the beginning of their third trimester were protected.

CONCLUSIONS

Our results demonstrate that neonatal vaccination and maternal vaccination confer protection in the baboon model and support further study of these strategies for protection of newborns from pertussis.

Infant baboons infected with respiratory syncytial virus develop clinical and pathological changes that parallel those of human infants

Respiratory syncytial virus (RSV) infection of the lower respiratory tract is the leading cause of respiratory failure among infants in the United States of America and annually results in >300,000 deaths worldwide. Despite the importance of RSV, there is no licensed vaccine, and no specific form of therapy. This is largely due to the absence of an appropriate animal model for the evaluation of vaccines and therapeutic agents. We inoculated anesthetized infant (4 wk) baboons (Papio anubis) with a human strain of RSV intranasally or intratracheally. Baboons were monitored daily for clinical changes. Anesthetized baboons were intubated at various intervals, and bronchoalveolar lavage (BAL) was performed for viral culture and determination of leukocyte counts. Sham-infected baboons served as controls. Necropsies were performed on infected baboons on days 1, 3, 5, 8, or 13 after inoculation, with pathological analysis and immunohistochemical staining of lung tissues to detect RSV antigen. Infected baboons developed tachypnea and reduced oxygenation peaking from 4 to 8 days after infection and persisting for ≥14 days. Virus was recoverable in BAL fluid up to 8 days following infection. Necropsy revealed intense interstitial pneumonia, sloughing of the bronchiolar epithelium, and obstruction of the bronchiolar lumen with inflammatory cells and sloughed epithelial cells. RSV antigen was identified in bronchiolar and alveolar epithelium. We conclude that RSV-infected infant baboons develop clinical and pathological changes that parallel those observed in human infants with RSV infection. The infant baboon represents a much-needed model for studying the pathogenesis of RSV infection and evaluating antivirals and vaccines.

Genome-wide real-time PCR for West Nile virus reduces the false-negative rate and facilitates new strain discovery

West Nile virus (WNV) causes significant morbidity and mortality worldwide. Transplant and transfusion recipients as well as the elderly are particularly at risk. WNV shows strain variation from season to season and from locale to locale. This poses a significant problem for diagnosis. Most assays use a single primer pair to detect WNV by QPCR, and can fail to detect novel stains. To overcome this limitation, a genome-wide, multiple primer-based real-time QPCR assay was developed for WNV. The same assay can be used for quantitation, viral variant discovery as well as for amplification of the entire viral genome using a single annealing temperature. It improves upon routine diagnosis as well as facilitates laboratory investigations of the pathology of WNV.

Evidence of simian virus 40 exposure in a colony of captive baboons

Simian virus 40 (SV40) is a polyomavirus for which non-human primates are the permissive host. The baboon (Papio spp.) is an old world monkey that is used in a variety of research investigations; however, natural infection of SV40 among baboons has not been thoroughly examined or reported. Initially, we were interested in determining the prevalence of SV40 infection among a captive colony of baboons based on the presence of antibodies to SV40 large T-antigen (Tag). An overall seroprevalence rate of >50% was found after screening sera from 142 baboons in the colony based on ELISA. Endpoint titer values for serum antibody binding to SV40 Tag reached as high as 1280 for 5 out of 142 baboons. Peptide binding assays revealed that a range of SV40 Tag epitopes are immunogenic in the baboon, and that individual animals differ in their humoral immune responses to SV40 Tag based on epitope recognition. Specificity to SV40 Tag and not some other primate polyomavirus encoded large Tag was further examined by serologic reactivity to peptide epitopes unique to SV40 Tag. Additional serology was performed to assess SV40 Tag reactivity by Western blot and whether antibodies were capable of neutralizing SV40 infectivity in vitro. Although antibodies with high levels of SV40 neutralization were observed in a number of the baboons, there was a lack of correlation between viral neutralization and antibodies to SV40 Tag. Further examination using molecular-based diagnosis and SV40 Tag specific real-time quantitative PCR determined that some of the baboons appeared to be exposed to SV40. DNA sequence analysis of the PCR products confirmed that SV40 Tag specific sequences were detected in baboons.

Baboon model for West Nile virus infection and vaccine evaluation

Animal models that closely mimic the human condition are of paramount significance to study pathogenic mechanisms, vaccine and therapy scenarios. This is particularly true for investigations that involve emerging infectious diseases. Nonhuman primate species represent an alternative to the more intensively investigated rodent animal models and in a number of instances have been shown to represent a more reliable predictor of the human response to infection. West Nile virus (WNV) has emerged as a new pathogen in the Americas. It has a 5% fatality rate, predominantly in the elderly and immune compromised. Typically, infections are cleared by neutralizing antibodies, which suggests that a vaccine would be efficacious. Previously, only macaques had been evaluated as a primate model for WNV vaccine design. The macaques did not develop WNV disease nor express the full complement of IgG subclasses that is found in humans. We therefore explored baboons, which exhibit the similar four IgG subclasses observed in humans as a new model for WNV infection and vaccine evaluation. In this present report, we describe the experimental infection of baboons with WNV and test the efficacy of an inactivated WNV vaccination strategy. All experimentally infected animals developed transient viremia and subsequent neutralizing antibodies. Anti-WNV IgM antibodies peaked at 20 days post-infection. Anti-WNV IgG antibodies appeared later and persisted past 60 days. Prior vaccination with chemically inactivated virus induced neutralizing titers and a fast, high titer IgG recall response, which resulted in lower viremia upon challenge. This report is the first to describe the development of the baboon model for WNV experimental infection and the utility of this model to characterize the immunologic response against WNV and a candidate WNV vaccine.

Methylene blue photoinactivation abolishes West Nile virus infectivity in vivo

The prevalence of West Nile virus (WNV) infections and associated morbidity has accelerated in recent years. Of particular concern is the recent demonstration that this virus can be transmitted by blood products and can cause severe illness and mortality in transfusion recipients. We have evaluated methylene blue (MB)+light as a safe and cost-effective means to inactivate WNV in vitro. This regimen inactivated WNV with an IC50 of 0.10 microM. Up to 10(7)pfu/ml of WNV could be inactivated by MB+light with no residual infectivity. MB+light inactivated three primary WNV isolates from the years 1999, 2002 and 2003 and prevented mortality in a murine model for WNV infection. Since MB is already approved for human use at a dose of 100mg/kg/day, we conjecture that MB+light treatment of blood products for high-risk patients will be efficacious and suitable for use in resource-limited settings.

The tumor microenvironment controls primary effusion lymphoma growth in vivo

Certain lymphomas in AIDS patients, such as primary effusion lymphoma (PEL), are closely associated with the lymphotropic gamma herpes virus Kaposi's sarcoma-associated herpes virus (KSHV), also called human herpesvirus 8. The virus is thought to be essential for tumorigenesis, yet systems to investigate PEL in vivo are rare. Here we describe PEL tumorigenesis in a new xenograft model. Embedded in Matrigel, PEL cells formed rapid, well-organized, and angiogenic tumors after s.c. implantation of C.B.17 SCID mice. Without Matrigel we did not observe comparable tumors, which implies that extracellular support and/or signaling aids PEL. All of the tumors maintained the KSHV genome, and the KSHV latent protein LANA/orf73 was uniformly expressed. However, the expression profile for key lytic mRNAs, as well as LANA-2/vIRF3, differed between tissue culture and sites of implantation. We did not observe a net effect of ganciclovir on PEL growth in culture or as xenograft. These findings underscore the importance of the microenvironment for PEL tumorigenesis and simplify the preclinical evaluation of potential anticancer agents.

SYBR green-based real-time quantitative PCR assay for detection of West Nile Virus circumvents false-negative results due to strain variability

Real-time quantitative PCR is used routinely for the high-throughput diagnosis of viral pathogens, such as West Nile virus (WNV). Rapidly evolving RNA viruses present a challenge for diagnosis because they accumulate mutations that may render them undetectable. To explore the effect of sequence variations on assay performance, we generated every possible single point mutation within the target region of the widely used TaqMan assay for WNV and found that the TaqMan assay failed to detect 47% of possible single nucleotide variations in the probe-binding site and was unable to detect any targets with more than two mutations. In response, we developed and validated a less expensive assay with the intercalating dye SYBR green. The SYBR green-based assay was as sensitive as the TaqMan assay for WNV. Importantly, it detected 100% of possible WNV target region variants. The assay developed here adds an additional layer of protection to guard against false-negative results that result from natural variations or drug-directed selection and provides a rapid means to identify such variants for subsequent detailed analysis.

Real-time Quantitative PCR Arrays for Virally-associated Cancers

Virally-associated cancers are unique in that their origin is typically well defined and suitable to genomic analysis on a smaller scale. We recently reported the transcription profile of Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) in Kaposi's sarcoma (KS) using a real-time quantitative PCR (QPCR) array. This review explores the advantages and limitations of such an approach as well as the possibilities of extending PCR-based profiling to human cancers. Since real-time QPCR records a truly quantitative transcription profile, this technology will improve statistical analysis and solidify clinical decision-making.