Commensal bacteria inhibit viral infections via a tryptophan metabolite.

There is growing appreciation that commensal bacteria impact the outcome of viral infections, though the specific bacteria and their underlying mechanisms remain poorly understood. Studying a simian-human immunodeficiency virus (SHIV)-challenged cohort of pediatric nonhuman primates, we bioinformatically associated Lactobacillus gasseri and the bacterial family Lachnospiraceae with enhanced resistance to infection. We experimentally validated these findings by demonstrating two different Lachnospiraceae isolates, Clostridium immunis and Ruminococcus gnavus, inhibited HIV replication in vitro and ex vivo. Given the link between tryptophan catabolism and HIV disease severity, we found that an isogenic mutant of C. immunis that lacks the aromatic amino acid aminotransferase (ArAT) gene, which is key to metabolizing tryptophan into 3-indolelactic acid (ILA), no longer inhibits HIV infection. Intriguingly, we confirmed that a second commensal bacterium also inhibited HIV in an ArAT-dependent manner, thus establishing the generalizability of this finding. In addition, we found that purified ILA inhibited HIV infection by agonizing the aryl hydrocarbon receptor (AhR). Given that the AhR has been implicated in the control of multiple viral infections, we demonstrated that C. immunis also inhibited human cytomegalovirus (HCMV) infection in an ArAT-dependent manner. Importantly, metagenomic analysis of individuals at-risk for HIV revealed that those who ultimately acquired HIV had a lower fecal abundance of the bacterial ArAT gene compared to individuals who did not, which indicates our findings translate to humans. Taken together, our results provide mechanistic insights into how commensal bacteria decrease susceptibility to viral infections. Moreover, we have defined a microbiota-driven antiviral pathway that offers the potential for novel therapeutic strategies targeting a broad spectrum of viral pathogens.

Sutterella and its metabolic pathways positively correlate with vaccine-elicited antibody responses in infant rhesus macaques.

Introduction: It is becoming clearer that the microbiota helps drive responses to vaccines; however, little is known about the underlying mechanism. In this study, we aimed to identify microbial features that are associated with vaccine immunogenicity in infant rhesus macaques. Methods: We analyzed 16S rRNA gene sequencing data of 215 fecal samples collected at multiple timepoints from 64 nursery-reared infant macaques that received various HIV vaccine regimens. PERMANOVA tests were performed to determine factors affecting composition of the gut microbiota throughout the first eight months of life in these monkeys. We used DESeq2 to identify differentially abundant bacterial taxa, PICRUSt2 to impute metagenomic information, and mass spectrophotometry to determine levels of fecal short-chain fatty acids and bile acids. Results: Composition of the early-life gut microbial communities in nursery-reared rhesus macaques from the same animal care facility was driven by age, birth year, and vaccination status. We identified a Sutterella and a Rodentibacter species that positively correlated with vaccine-elicited antibody responses, with the Sutterella species exhibiting more robust findings. Analysis of Sutterella-related metagenomic data revealed five metabolic pathways that significantly correlated with improved antibody responses following HIV vaccination. Given these pathways have been associated with short-chain fatty acids and bile acids, we quantified the fecal concentration of these metabolites and found several that correlated with higher levels of HIV immunogen-elicited plasma IgG. Discussion: Our findings highlight an intricate bidirectional relationship between the microbiota and vaccines, where multiple aspects of the vaccination regimen modulate the microbiota and specific microbial features facilitate vaccine responses. An improved understanding of this microbiota-vaccine interplay will help develop more effective vaccines, particularly those that are tailored for early life.

Effects of Deslorelin on Testosterone Secretion and Testicular Volume in Male Rhesus Macaques (Macaca mulatta).

Sterility in male NHP has long been achieved through surgical castration or vasectomy. However, these techniques are irreversible, require a surgical procedure, and have potential consequences such as sperm granulomas and long recovery time. Deslorelin is a gonadotropin-releasing hormone agonist that temporarily and reversibly suppresses sex hormone secretion. Our goal in this study was to investigate the effects of deslorelin on testosterone secretion and testicular volume in male rhesus macaques (Macaca mulatta). Male macaques (n = 4) each received two, 4.7-mg deslorelin implants subcutaneously in the interscapular region. Serum testosterone and testicular volume were then monitored at specific time points until 10 mo after treatment. Testosterone suppression was defined as testosterone levels lower than 0.6 ng/mL for a sustained period of at least 30 d. After implantation, mean testicular volume was significantly reduced by day 121. Testosterone suppression was observed in all subjects. However, the time from implantation to testosterone suppression and duration of suppression varied. Two macaques were hormonally suppressed by day 26 after implantation and remained suppressed for at least 6 mo. The other 2 macaques were hormonally suppressed by 2 mo after implantation; of these two, one remained suppressed for 70 days while the other was suppressed for at least 245 days. We conclude that deslorelin can safely suppress testosterone secretion in male rhesus macaques, but individual variation in onset and duration of action should be considered when establishing reimplantation time points and potential return to reproductive activity.

The Pharmacokinetics of Subcutaneous Methylnaltrexone Bromide in Rhesus Macaques (Macaca mulatta).

Opioids are an integral component of pain management for nonhuman primates. These potent analgesics also adverse gastrointestinal (GI) effects that include constipation, bloating, and delayed gastric emptying. Methylnaltrexone bromide (MNTX) is a selective, peripherally acting µ- and κ-opioid receptor antagonist that can be used to mitigate the GI effects associated with opioid administration. Unlike naltrexone, a similar drug in this class, MNTX possesses an N-methyl-quaternary amine group that prevents it from crossing the blood brain barrier. This blockage allows inhibition of peripheral GI opioid receptors without affecting opioid-mediated analgesia in the central nervous system. We conducted a pharmacokinetic analysis of MNTX in serum and CSF of 6 healthy juvenile male rhesus macaques after subcutaneous administration of a 0.15-mg/kg dose. We hypothesized that the macaques would demonstrate a Tmax of 0.5 h, similar to that of humans, and that no MNTX would be detected in the CSF. This treatment resulted in a peak serum concentration of 114 ± 44 ng/mL at 0.25 ± 0.00 h; peak CSF at concentrations were 0.34 ± 0.07 ng/mL at the Tmax. These data show that subcutaneous administration of MNTX to rhesus macaques may block peripheral adverse effects of opioids without interfering with their central analgesic effects.

Early-life behavioral features are associated with chronic emesis in rhesus macaques (Macaca mulatta).

Chronic emesis (CE) is a poorly understood condition in human and nonhuman primates that negatively impacts the quality of life. Early identification of risk factors for the development of CE is likely to improve the ability to manage CE cases successfully and is, therefore, desirable. Using a case-control study, we reviewed the necropsy records of the California National Primate Research Center and identified 24 animals with recorded CE, defined as five or more incidents of emesis in 1 month. A group of 89 healthy rhesus macaques (Macaca mulatta), comparable in age and percent time housed indoors, was similarly identified. Next, we investigated the association between the occurrence of CE during later stages of life after infancy and the behavioral temperament scores attained in infancy, age, sex, birth location, rearing condition, history of self-injurious behavior (SIB), and the number of lifetime sedation events. Our analysis revealed that CE was associated with degrees of temperament constructs obtained in infancy (data was available for n = 113), such as Confidence (odds ratio (OR) = 0.45, 95% CI: 0.18, 1.08, p = 0.07), Gentleness (OR = 0.47, 95% CI: 0.23, 0.96, p = 0.03), Nervousness (OR = 2.04, 95% CI: 0.98, 4.23, p = 0.05), and Vigilance (OR = 0.36, 95% CI: 015, 0.87, p = 0.02), suggesting that CE is linked to behavioral phenomenon measured in early life, long before it becomes a medical concern. Our data suggest that CE was positively correlated with a history of SIB (OR 4.26, 95% CI: 0.98, 18.47, p = 0.04). Accurate prediction of CE can then assist behavioral and colony management professionals in making informed decisions regarding the care of animals at risk of developing CE. Moreover, the novel information we reported here could have valuable implications in human medicine, where gastrointestinal distress is a common complaint affecting a person's quality of life.

Cytomegalovirus infection disrupts the influence of short-chain fatty acid producers on Treg/Th17 balance.

BACKGROUND: Both the gut microbiota and chronic viral infections have profound effects on host immunity, but interactions between these influences have been only superficially explored. Cytomegalovirus (CMV), for example, infects approximately 80% of people globally and drives significant changes in immune cells. Similarly, certain gut-resident bacteria affect T-cell development in mice and nonhuman primates. It is unknown if changes imposed by CMV on the intestinal microbiome contribute to immunologic effects of the infection. RESULTS: We show that rhesus cytomegalovirus (RhCMV) infection is associated with specific differences in gut microbiota composition, including decreased abundance of Firmicutes, and that the extent of microbial change was associated with immunologic changes including the proliferation, differentiation, and cytokine production of CD8+ T cells. Furthermore, RhCMV infection disrupted the relationship between short-chain fatty acid producers and Treg/Th17 balance observed in seronegative animals, showing that some immunologic effects of CMV are due to disruption of previously existing host-microbe relationships. CONCLUSIONS: Gut microbes have an important influence on health and disease. Diet is known to shape the microbiota, but the influence of concomitant chronic viral infections is unclear. We found that CMV influences gut microbiota composition to an extent that is correlated with immunologic changes in the host. Additionally, pre-existing correlations between immunophenotypes and gut microbes can be subverted by CMV infection. Immunologic effects of CMV infection on the host may therefore be mediated by two different mechanisms involving gut microbiota. Video Abstract.

Hormonal Suppression in Female Rhesus Macaques (Macaca mulatta) Implanted Subcutaneously with Deslorelin.

Providing effective contraception for nonhuman primates (NHP) is challenging. Deslorelin acetate is a commercially available gonadotropin-releasing hormone (GnRH) agonist that may provide a relatively noninvasive, long-lasting, and potentially reversible alternative to standard NHP contraception methods. This study evaluated the duration of suppression of progesterone and estradiol in 6 adult female rhesus macaques (Macaca mulatta) that received a single subcutaneous 4.7 mg deslorelin implant. We hypothesized that deslorelin would suppress production of these hormones for 6 mo with a correspond- ing cessation of menses. Prior to implantation, blood was collected over 1 mo for baseline hormone analyses. Macaques were sedated at the onset of the next menstrual cycle and a 4.7 mg deslorelin implant was placed in the interscapular region. Blood was collected over the subsequent month at the same intervals used for the baseline collection schedule, and then every 7 d thereafter. Results showed that estradiol and progesterone transiently increased 1 to 3 d after implantation, then fell to basal levels within 6 d of implantation. The duration of hormone suppression (progesterone <0.5 ng/mL) varied among animals. Two macaques returned to cyclicity by 96 d and 113 d after implantation, while hormones remained suppressed in the other 4 macaques at 6 mo after implantation. Cessation of menses correlated with hormone suppression except in 1 animal that continued to have sporadic vaginal bleeding despite progesterone remaining below 0.5 ng/mL. This study indicates that deslorelin is a noninvasive and long-lasting contraceptive method in female rhesus macaques. However, individual variation should be considered when determining reimplantation intervals.

Early post-infection treatment of SARS-CoV-2 infected macaques with human convalescent plasma with high neutralizing activity had no antiviral effects but moderately reduced lung inflammation.

Early in the SARS-CoV-2 pandemic, there was a high level of optimism based on observational studies and small controlled trials that treating hospitalized patients with convalescent plasma from COVID-19 survivors (CCP) would be an important immunotherapy. However, as more data from controlled trials became available, the results became disappointing, with at best moderate evidence of efficacy when CCP with high titers of neutralizing antibodies was used early in infection. To better understand the potential therapeutic efficacy of CCP, and to further validate SARS-CoV-2 infection of macaques as a reliable animal model for testing such strategies, we inoculated 12 adult rhesus macaques with SARS-CoV-2 by intratracheal and intranasal routes. One day later, 8 animals were infused with pooled human CCP with a high titer of neutralizing antibodies (RVPN NT50 value of 3,003), while 4 control animals received normal human plasma. Animals were monitored for 7 days. Animals treated with CCP had detectable but low levels of antiviral antibodies after infusion. In comparison to the control animals, CCP-treated animals had similar levels of viral RNA in upper and lower respiratory tract secretions, similar detection of viral RNA in lung tissues by in situ hybridization, but lower amounts of infectious virus in the lungs. CCP-treated animals had a moderate, but statistically significant reduction in interstitial pneumonia, as measured by comprehensive lung histology. Thus overall, therapeutic benefits of CCP were marginal and inferior to results obtained earlier with monoclonal antibodies in this animal model. By highlighting strengths and weaknesses, data of this study can help to further optimize nonhuman primate models to provide proof-of-concept of intervention strategies, and guide the future use of convalescent plasma against SARS-CoV-2 and potentially other newly emerging respiratory viruses.

Enteric Viruses Nucleic Acids Distribution along the Digestive Tract of Rhesus Macaques with Idiopathic Chronic Diarrhea.

Idiopathic chronic diarrhea (ICD) is a little understood common clinical problem in captive rhesus macaques claiming 33% of medical culls unrelated to research. The eukaryotic virome in digestive tract tissues collected at necropsy from nine animals with ICD was characterized using viral metagenomics. We compared the distribution of viral reads in tissues and mucosal scrapings from the stomach, duodenum, jejunum, ileum, and the proximal, transverse, and distal colons. In situ hybridization (ISH) using viral probes were performed on fixed tissues. Deep sequencing revealed multiple viruses in the Parvoviridae and Picornaviridae family. Tissues and mucosal scraping from the same locations showed closely related viral reads contents while different gut tissues from the same animal varied widely. ISH showed punctuated staining for both RNA and DNA viruses in the distal colon. Parvovirus staining was also detected in the stomach/duodenum/jejunum in distinct oval-shaped structures. The location of enteric viral nucleic acid differed widely between different viral families and along the length of the digestive tract.

Idiopathic Chronic Diarrhea in Rhesus Macaques Is Not Associated with Enteric Viral Infections.

While recent changes in treatment have reduced the lethality of idiopathic chronic diarrhea (ICD), this condition remains one of the most common causes of rhesus macaque deaths in non-human primate research centers. We compared the viromes in fecal swabs from 52 animals with late stage ICD and 41 healthy animals. Viral metagenomics targeting virus-like particles was used to identify viruses fecally shed by each animal. Five viruses belonging to the Picornaviridae, one to the Caliciviridae, one to the Parvoviridae, and one to the Adenoviridae families were identified. The fraction of reads matching each viral species was then used to estimate and compare viral loads in ICD cases versus healthy controls. None of the viruses detected in fecal swabs were strongly associated with ICD.

Early post-infection treatment of SARS-CoV-2 infected macaques with human convalescent plasma with high neutralizing activity reduces lung inflammation.

Early in the SARS-CoV-2 pandemic, there was a high level of optimism based on observational studies and small controlled trials that treating hospitalized patients with convalescent plasma from COVID-19 survivors (CCP) would be an important immunotherapy. However, as more data from controlled trials became available, the results became disappointing, with at best moderate evidence of efficacy when CCP with high titers of neutralizing antibodies was used early in infection. To better understand the potential therapeutic efficacy of CCP, and to further validate SARS-CoV-2 infection of macaques as a reliable animal model for testing such strategies, we inoculated 12 adult rhesus macaques with SARS-CoV-2 by intratracheal and intranasal routes. One day later, 8 animals were infused with pooled human CCP with a high titer of neutralizing antibodies (RVPN NT 50 value of 3,003), while 4 control animals received normal human plasma. Animals were monitored for 7 days. Animals treated with CCP had detectable levels of antiviral antibodies after infusion. In comparison to the control animals, they had similar levels of virus replication in the upper and lower respiratory tract, but had significantly reduced interstitial pneumonia, as measured by comprehensive lung histology. By highlighting strengths and weaknesses, data of this study can help to further optimize nonhuman primate models to provide proof-of-concept of intervention strategies, and guide the future use of convalescent plasma against SARS-CoV-2 and potentially other newly emerging respiratory viruses. AUTHOR SUMMARY: The results of treating SARS-CoV-2 infected hospitalized patients with COVID-19 convalescent plasma (CCP), collected from survivors of natural infection, have been disappointing. The available data from various studies indicate at best moderate clinical benefits only when CCP with high titer of neutralizing antibodies was infused early in infection. The macaque model of SARS-CoV-2 infection can be useful to gain further insights in the value of CCP therapy. In this study, animals were infected with SARS-CoV-2 and the next day, were infused with pooled human convalescent plasma, selected to have a very high titer of neutralizing antibodies. While administration of CCP did not result in a detectable reduction in virus replication in the respiratory tract, it significantly reduced lung inflammation. These data, combined with the results of monoclonal antibody studies, emphasize the need to use products with high titers of neutralizing antibodies, and guide the future development of CCP-based therapies.

Early treatment with a combination of two potent neutralizing antibodies improves clinical outcomes and reduces virus replication and lung inflammation in SARS-CoV-2 infected macaques.

There is an urgent need for effective therapeutic interventions against SARS-CoV-2, including new variants that continue to arise. Neutralizing monoclonal antibodies have shown promise in clinical studies. We investigated the therapeutic efficacy of a combination of two potent monoclonal antibodies, C135-LS and C144-LS that carry half-life extension mutations, in the rhesus macaque model of COVID-19. Twelve young adult macaques (three groups of four animals) were inoculated intranasally and intra-tracheally with a high dose of SARS-CoV-2 and 24 hours later, treated intravenously with a high (40 mg/kg) or low (12 mg/kg) dose of the C135-LS and C144-LS antibody combination, or a control monoclonal antibody. Animals were monitored for 7 days. Compared to the control animals, animals treated with either dose of the anti-SARS-CoV-2 antibodies showed similarly improved clinical scores, lower levels of virus replication in upper and lower respiratory tract, and significantly reduced interstitial pneumonia, as measured by comprehensive lung histology. In conclusion, this study provides proof-of-concept in support of further clinical development of these monoclonal antibodies against COVID-19 during early infection.

Comparison of Insulins Glargine and Degludec in Diabetic Rhesus Macaques (Macaca mulatta) with CGM Devices.

Treating and monitoring type 2 diabetes mellitus (T2DM) in NHP can be challenging. Multiple insulin and hypoglycemic therapies and management tools exist, but few studies demonstrate their benefits in a NHP clinical setting. The insulins glargine and degludec are long-acting insulins; their duration of action in humans exceeds 24 and 42 h, respectively. In the first of this study's 2 components, we evaluated whether insulin degludec could be dosed daily at equivalent units to glargine to achieve comparable blood glucose (BG) reduction in diabetic rhesus macaques (Macaca mulatta) with continuous glucose monitoring (CGM) devices. The second component assessed the accuracy of CGM devices in rhesus macaques by comparing time-stamped CGM interstitial glucose values, glucometer BG readings, and BG levels measured by using an automated clinical chemistry analyzer from samples that were collected at the beginning and end of each CGM device placement. The CGM devices collected a total of 21,637 glucose data points from 6 diabetic rhesus macaques that received glargine followed by degludec every 24 h for 1 wk each. Ultimately, glucose values averaged 29 mg/dL higher with degludec than with glargine. Glucose values were comparable between the CGM device, glucometer, and chemistry analyzer, thus validating that CGM devices as reliable for measuring BG levels in rhesus macaques. Although glargine was superior to degludec when given at the same dose (units/day), both are safe and effective treatment options. Glucose values from CGM, glucometers, and chemistry analyzers provided results that were analogous to BG values in rhesus macaques. Our report further highlights critical clinical aspects of using glargine as compared with degludec in NHP and the benefits of using CGM devices in macaques.

Comparison of predictors for terminal disease progression in simian immunodeficiency virus/simian-HIV-infected rhesus macaques.

OBJECTIVES: CD4+ T-cell decline and increasing virus levels are considered hallmarks of HIV/AIDS pathogenesis but we previously demonstrated in rhesus macaques that tissue macrophage destruction by simian immunodeficiency virus (SIV) infection associated with increased monocyte turnover also appear to impact pathogenesis. It remains unclear, however, which factors best predict onset of terminal disease progression and survival time. The objective of this study, therefore, was to directly compare these co-variates of infection for predicting survival times in retrospective studies of SIV/simian-HIV (SHIV)-infected adult rhesus macaques. METHODS: Rhesus macaques were infected with various strains of SIV/SHIV and evaluated longitudinally for monocyte turnover, CD4+ T-cell loss, plasma viral load, and SIV/SHIV strain. Correlation analyses and machine learning algorithm modeling were applied to compare relative contributions of each of the co-variates to survival time. RESULTS: All animals with AIDS-related clinical signs requiring euthanasia exhibited increased monocyte turnover regardless of CD4+ T-cell level, viral strain, or plasma viral load. Regression analyses and machine learning algorithms indicated a stronger correlation and contribution between increased monocyte turnover and reduced survival time than between CD4+ T-cell decline, plasma viral load, or virus strain and reduced survival time. Decision tree modeling categorized monocyte turnover of 13.2% as the initial significant threshold that best predicted decreased survival time. CONCLUSION: These results demonstrate that monocytes/macrophages significantly affect HIV/SIV pathogenesis outcomes. Monocyte turnover analyses are not currently feasible in humans, so there is a need to identify surrogate biomarkers reflecting tissue macrophage damage that predict HIV infection disease progression.

Evolution of ocular defects in infant macaques following in utero Zika virus infection.

Congenital Zika syndrome (CZS) is associated with microcephaly and various neurological, musculoskeletal, and ocular abnormalities, but the long-term pathogenesis and postnatal progression of ocular defects in infants are not well characterized. Rhesus macaques are superior to rodents as models of CZS because they are natural hosts of the virus and share similar immune and ocular characteristics, including blood-retinal barrier characteristics and the unique presence of a macula. Using a previously described model of CZS, we infected pregnant rhesus macaques with Zika virus (ZIKV) during the late first trimester and characterized postnatal ocular development and evolution of ocular defects in 2 infant macaques over 2 years. We found that one of them exhibited colobomatous chorioretinal atrophic lesions with macular and vascular dragging as well as retinal thinning caused by loss of retinal ganglion neuron and photoreceptor layers. Despite these congenital ocular malformations, axial elongation and retinal development in these infants progressed at normal rates compared with healthy animals. The ZIKV-exposed infants displayed a rapid loss of ZIKV-specific antibodies, suggesting the absence of viral replication after birth, and did not show any behavioral or neurological defects postnatally. Our findings suggest that ZIKV infection during early pregnancy can impact fetal retinal development and cause congenital ocular anomalies but does not appear to affect postnatal ocular growth.

Clinical and Immunological Metrics During Pediatric Rhesus Macaque Development.

Background: Clinical measurements commonly used to evaluate overall health of laboratory animals including complete blood count, serum chemistry, weight, and immunophenotyping, differ with respect to age, development, and environment. This report provides comprehensive clinical and immunological reference ranges for pediatric rhesus macaques over the first year of life. Methods: We collected and analyzed blood samples from 151 healthy rhesus macaques, aged 0-55 weeks, and compared mother-reared infants to two categories of nursery-reared infants; those on an active research protocol and those under derivation for the expanded specific-pathogen-free breeding colony. Hematology was performed on EDTA-anticoagulated blood using a Sysmex XT2000i, and serum clinical chemistry was performed using the Beckman AU480 chemistry analyzer. Immunophenotyping of whole blood was performed with immunofluorescence staining and subsequent flow cytometric analysis on a BD LSRFortessa. Plasma cytokine analysis was performed using a Millipore multiplex Luminex assay. Results: For hematological and chemistry measurements, pediatric reference ranges deviate largely from adults. Comparison of mother-reared and nursery-reared animals revealed that large differences depend on rearing conditions and diet. Significant differences found between two nursery-reared cohorts (research and colony animals) indicate large influences of experimental factors and anesthetic events on these parameters. Immune cells and cytokine responses presented with distinct patterns for infants depending on age, birth location, and rearing conditions. Conclusions: Our results illustrate how the immune system changed over time and that there was variability among pediatric age groups. Reference ranges of results reported here will support interpretations for how infection and treatment may skew common immune correlates used for assessment of pathology or protection in research studies as well as help veterinarians in the clinical care of infant non-human primates. We highlighted the importance of using age-specific reference comparisons for pediatric studies and reiterated the utility of rhesus macaques as a model for human studies. Given the rapid transformation that occurs in multiple tissue compartments after birth and cumulative exposures to antigens as individuals grow, a better understanding of immunological development and how this relates to timing of infection or vaccination will support optimal experimental designs for developing vaccines and treatment interventions.

A combination of two human monoclonal antibodies limits fetal damage by Zika virus in macaques.

Human infection by Zika virus (ZIKV) during pregnancy can lead to vertical transmission and fetal aberrations, including microcephaly. Prophylactic administration of antibodies can diminish or prevent ZIKV infection in animal models, but whether passive immunization can protect nonhuman primates and their fetuses during pregnancy has not been determined. Z004 and Z021 are neutralizing monoclonal antibodies to domain III of the envelope (EDIII) of ZIKV. Together the two antibodies protect nonpregnant macaques against infection even after Fc modifications to prevent antibody-dependent enhancement (ADE) in vitro and extend their half-lives. Here we report on prophylactic coadministration of the Fc-modified antibodies to pregnant rhesus macaques challenged three times with ZIKV during first and second trimester. The two antibodies did not entirely eliminate maternal viremia but limited vertical transmission, protecting the fetus from neurologic damage. Thus, maternal passive immunization with two antibodies to EDIII can shield primate fetuses from the harmful effects of ZIKV.

DNA vaccination before conception protects Zika virus-exposed pregnant macaques against prolonged viremia and improves fetal outcomes.

Zika virus (ZIKV) infection of pregnant women is associated with congenital Zika syndrome (CZS) and no vaccine is available, although several are being tested in clinical trials. We tested the efficacy of ZIKV DNA vaccine VRC5283 in a rhesus macaque model of congenital ZIKV infection. Most animal vaccine experiments have a set pathogen exposure several weeks or months after vaccination. In the real world, people encounter pathogens years or decades after vaccination, or may be repeatedly exposed if the virus is endemic. To more accurately mimic how this vaccine would be used, we immunized macaques before conception and then exposed them repeatedly to ZIKV during early and mid-gestation. In comparison to unimmunized animals, vaccinated animals had a significant reduction in peak magnitude and duration of maternal viremia, early fetal loss, fetal infection, and placental and fetal brain pathology. Vaccine-induced neutralizing antibody titers on the day of first ZIKV exposure were negatively associated with the magnitude of maternal viremia, and the absence of prolonged viremia was associated with better fetal outcomes. These data support further clinical development of ZIKV vaccine strategies to protect against negative fetal outcomes.

Experimental Infection of Mice with Veronaea botryosa as a Model for Human Phaeohyphomycosis.

Veronaea botryosa is a ubiquitous, dematiaceous mold capable of causing cutaneous and subcutaneous lesions in humans. In the last decade, V. botryosa has been associated with emergent systemic fungal infections in aquatic animals, including cultured sturgeon (Acipenser spp.), captive amphibians, and wild reptiles. Recently, repetitive extragenic palindromic PCR (rep-PCR) fingerprinting has demonstrated intraspecific variability among V. botryosa isolates from different clinically affected hosts and geographic regions. However, little is known regarding the pathogenic potential of the different genetic clades, and no mammalian model currently exists to investigate V. botryosa phaeohyphomycosis. In this study, we inoculated immunocompetent heterozygotic (nu/+) and immunodeficient homozygotic (nu/nu) Hsd:Athymic Nude-Fox1nu mice subcutaneously or through orogastric gavage with 1 of 3 representative V. botryosa strains that had been recovered from white sturgeon (Acipenser transmontanus), green sea turtle (Chelonia mydas), and human hosts and typed by using rep-PCR analysis. Daily mortality and morbidity were recorded, and dissemination of the fungus was investigated through culture of splenic samples and histologic analysis of the injection site, regional lymph nodes, salivary gland, spleen, liver, mesenteric lymph node, and gastrointestinal tract. No differences in survival, fungal burden, or dissemination were observed between fungal strains, routes of inoculation, or host immune status. Fungal infection was observed after subcutaneous inoculation only, was localized to the inoculation site, and was identified in both nu/nu and nu/+ mice. Fungal strain variability was not associated with virulence in a murine model of infection, and this novel mouse model of V. botryosa phaeohyphomycosis recapitulates the human clinical condition.