Aerosol Infection Research Articles

INFECTION CONTROL IN DENTAL CLINICS DURING COVID 19 –Original Review

The outbreak of severe acute respiratory syndrome corona virus 2 (SARS COV 2) and its linked corona virus disease has troubled the entire world community led to a serious public health concerns. Despite the various efforts to stop the spread of this disease globally, the outbreak is still on the rise because of the community spread pattern of this disease. This is believed to have originated in bats pangolins initially later it got transmitted to humans. Once it comes in the human body , this corona virus remains abundantly present in nasopharyngeal and salivary secretions of affected patients. Its spreading nature is mainly through the respiratory droplet spread / aerosol infection. Dental professionals, including Orthodontists , Oral Surgeons , Periodontists, Endodontists and Prosthodontists are all at high risk, since they may encounter patients with suspected or confirmed SARS COV 2 infection will have to act accordingly not only to provide care but at the same time prevent nosocomial spread of infection. Thus, the aim of this article is to provide a brief detailing of the cause, sign symptoms and different routes of transmission of this infection. In addition specific recommendations for dental practice are suggested for patient screening, infection control strategies and patient management protocol . KEY WORDS Coronavirus ,COVID 19, SARS COV 2 ,Dental practice ,Orthodontics ,OMFS, severe acute respiratory syndrome .

The C-X-C motif chemokine 17 plays a minimal role during lung infection with hypervirulent Mycobacterium tuberculosis

Abstract The C-X-C motif chemokine 17 (CXCL17) is a novel mucosal chemotactic factor for myeloid cells that displays bactericidal activity against respiratory pathogens in vitro. Although CXCL17 is constitutively expressed along the respiratory tract, its function during lung infections has not been tested in vivo. We previously showed that the CXCL17 gene is overexpressed in innate lymphoid cells (ILCs) isolated from the lung of patients with active pulmonary tuberculosis (TB). Thus, in the current study we further explored the role of CXCL17 in the defense against Mycobacterium tuberculosis (Mtb). In a mouse model of aerosol infection with the prototype W-Beijing lineage Mtb strain, hypervirulent HN878, we found that CXCL17 is actively produced at the lung during the acute and chronic stages of disease, with levels peaking at 30 days post-infection. Using in vitro infection assays, we observed that lung epithelial cells, bone marrow-derived macrophages (BMDMs), and bone marrow-derived dendritic cells (BMDCs) can become cellular sources of CXCL17 in response to Mtb. In humans, the serum levels of CXCL17 are significatively higher among individuals with latent TB infection (LTBI) than in active TB patients, suggesting a protective role. However, low serum levels of CXCL17 do not correlate with increased lung damage among active TB subjects. Furthermore, CXCL17−/− mice do not exhibit increased susceptibility to Mtb HN878 infection as compared to wild type controls. Finally, administration of exogenous recombinant CXCL17 into the airways of Mtb-infected animals does not impact their lung bacterial burden despite increased recruitment of myeloid cells to the pulmonary tissue. Our data suggest that CXCL17 plays a redundant role during TB.

Mice infected with the hypervirulent Mycobacterium tuberculosis HN878 strain develop lung lesions resembling human tubercle granulomas

Abstract The aerosol infection of mice with lab-adapted Mycobacterium tuberculosis (Mtb) strains in not an ideal model to study the immune parameters crucial for structural organization of protective human tuberculosis (TB) granulomas. Since experimentation in larger animals that mimic human lung granulomatous responses is expensive, a cost-effective animal model recapitulating morphological aspects of human granulomas is needed. Here, we addressed whether the use of hypervirulent Mtb strains could be a better strategy to improve the mouse model of TB. Hence, we infected C57BL/6 mice with a low dose of aerosolized Mtb HN878 and histologically analyzed infected lung tissues at different time points after infection. We found that granulomas that developed early after Mtb HN878 infection resemble human and NHPs granulomas, except for the lack of multinucleated giant cells. These structures displayed a central core of macrophages surrounded by a lymphocyte cuff. Immunofluorescence analysis showed that the presence of Mtb within mouse human-like granulomas was restricted to the central core area where some macrophages also expressed iNOS. Furthermore, increased formation of B cell lymphoid follicles expressing CXCL13 and germinal center markers was observed at the peripheral lymphocyte cuffs of human-like granulomas. As B cell follicles are indicators of protective immunity in humans, we addressed whether their formation was crucial for Mtb control. In Ighm−/− B cell deficient mice, we found an increased susceptibility to Mtb HN878 infection and enhanced lung inflammation at 50 days post-infection as compared to wild-type mice. Thus, our data supports the use of Mtb HN878 infection to model human TB granuloma formation in mice.

Reply to "Protecting against COVID-19 aerosol infection during intubation".

Dear Editor, We appreciate the comments by Tseng et al1 on our recent article Wu et al2 published in the current issue of the Journal of the Chinese Medical Association. Indeed, it is very crucial to protect health care workers (HCWs) in this pandemic. Not only HCWs safeguard patient care, but also they are at high risk of contracting this contagious disease. Studies indicate that 3.8% (1716/44 672) of HCWs during the outbreak in China (as of February 11, 2020) were infected and 14.8% of confirmed cases were classified as severe or critical.3,4 A random sample survey in March 2020, in Noord-Brabant, Netherlands, revealed nearly 4% of the hospital staff is infected with this novel coronavirus, but the percentages vary per hospital (0%-10%).5 Mortality did happen even among young doctors. As we emphasized in previous overview and the authors concur that “stringent protection procedures should be conducted for high-risk procedures.”2 Endotracheal tube intubation by all means is one of the most dangerous maneuver. It has been shown that aerosol might be generated during intubation and viral-containing droplets can floating or contaminate different surfaces for many hours.6 Particularly, viral loads are high in the early stage of symptom onset and lung-derived samples (such as sputum or aspirate) contain high viral load when the patient’s condition deteriorates and need intubation.7,8 It has been shown that surgical face masks can effectively prevent viral spreading of many respiratory viruses, including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).9 However, surgical face masks need to be removed during intubation. The authors invented a transparent acrylic “aerosol box” to protect the person who conducts intubation from aerosol spreading or droplet contamination. This device seems promising in reducing the chance of infection during intubation. It would be very informative if the authors could demonstrate or show experimental data that how effective “the box” can contain viral-containing droplets inside the box and protect people from infection.

Synergistic Activity of Clofazimine and Clarithromycin in an Aerosol Mouse Model of Mycobacterium avium Infection.

Infections with nontuberculous mycobacteria (NTM) have a poor prognosis in patients with underlying respiratory diseases. Clofazimine (CFZ) showed both experimental and clinical promising results against clinically relevant NTM. However, there are no data on CFZ in combination with the current recommended treatment; therefore, we aimed to study its in vivo activity in an aerosol mouse model of Mycobacterium avium In an aerosol infection BALB/c mouse model using M. avium strain Chester, we treated 58 mice with four combinations of rifampin (RIF) at 10 mg/kg, CFZ at 25 mg/kg, and clarithromycin (CLR) and ethambutol (EMB) at 100 mg/kg. Treatment efficacy was assessed on the basis of lung CFU counts after 2 (M2) and 4 (M4) months of treatment. At M2, CLR-RIF-EMB was slightly but significantly more efficient than CFZ-RIF-EMB (3.02 ± 0.12 versus 3.55 ± 0.28, respectively, P < 0.01), whereas CLR-CFZ-EMB and CLR-CFZ-RIF-EMB dramatically decreased lung CFU counts by 4.32 and 4.47 log10, respectively, compared to untreated group. At M4, CLR-RIF-EMB was significantly more efficient than CFZ-RIF-EMB (2 ± 0.53 versus 2.66 ± 0.22, respectively, P = 0.01). The addition of CLZ to CLR dramatically decreased the lung CFU count, with CFU counts 5.41 and 5.79 log10 lower in the CLR-CFZ-EMB and CLR-CFZ-RIF-EMB groups, respectively, than in the untreated group. The addition of CFZ to CLR seems to improve the efficacy of CLR as early as M2 and was confirmed at M4. CFZ, in addition to RIF and EMB, on the other hand, is less effective than CLR-RIF-EMB. These results need to be confirmed by similar studies along with CFZ potential for shortening treatment.

Prevention of exposure to and spread of COVID-19 using air purifiers: challenges and concerns.

Coronavirus disease 2019 (COVID-19) is now a pandemic. The Korean government has declared a red alert, which is the highest level of the national infectious disease alert system, and the World Health Organization has similarly declared its highest-level pandemic alert (phase 6). The spread of COVID-19 is an unprecedented worldwide public health problem that governments and individuals must work to overcome. Recently, an infection cluster arose in a call center in Seoul. To support call center companies, the Korean Ministry of Employment and Labor has proposed covering the costs of installing partitions and air purifiers, providing hand sanitizers, and supplying masks to prevent droplet and aerosol infections. Air purifiers are expected to be installed on the floor with the exhaust outlets at a higher level, such as the level of the desks or breathing zones of workers. When a worker coughs or releases droplets near a colleague’s respiratory system, the droplets may spread throughout the call center via air flow from air purifier. In this fashion, a single infected person can give rise to an infection cluster. Attempts to prevent infection must not lead to new infections, and the installation of air purifiers may cause new problems. Therefore, using air purifiers to control the spread of COVID-19 should be approached with caution.

Protecting against COVID-19 aerosol infection during intubation.

DEAR EDITOR, We read with great interest the review article regarding the outbreak of coronavirus disease 2019 (COVID-19) by Wu et al.1 According to recent figures posted on worldometer,2 there are over 1.2 million confirmed cases of coronavirus resulting in over 66 5000 deaths worldwide. The novel coronavirus was first reported in Wuhan, China, in late December of 2019.3 China issued a lockdown on all major cities to prevent and contain the spread of the virus; unfortunately, it was too late. Sporadic cases began to first appear in Asia, then Europe and the Americas, and finally affecting 208 countries and territories.2 This pandemic has caught global healthcare workers off-guard. As human to human transmission4 became evident, a surge of infected patients needing hospitalization and requiring mechanical ventilation increased exponentially. Recently it has been reported that the virus responsible for COVID-19 can be viable in aerosols for up to 3 hours and remain detectable on plastic and stainless steel surfaces for approximately 72 hours.5 Personal protective equipment (PPE) including face mask, goggles, gloves, and gown has become a necessity to minimize the exposure to the deadly pathogenic virus. Stringent protection procedures should be conducted for high-risk procedures such as endoscopy, Ambu bagging, and endotracheal tube intubation.1 During the intubation process, medical personnel are at the highest risk of being exposed and infected. As a preventive measure, a simple, low-cost device was invented to give physicians extra protection from any aerosol particles that could be released during the intubation procedure. The device consists of a transparent acrylic box with an opening on one side allowing it to fit over the patient’s chest and neck, while the opposite side has two small holes where the doctor’s hands can be inserted during the intubation. The “aerosol box” has been registered under a Creative Commons license and is free to the public as long as it is properly attributed to the designer and not used for commercial purposes. The schematics is available at https://sites.google.com/view/aerosolbox/home. This device has already been adopted by some hospitals in Taiwan, Hong Kong, Philippines, Canada, United Kingdom, and the United States. A group from Boston Medical Center developed a prototype with the design and streamed a video showing the effectiveness of using the aerosol box to protect clinicians during the intubation procedure.6 Changes to the original design may be necessary to fit the respective needs of the physician and/or patient—availability of video-assisted laryngoscope, large hands, and patient body mass index (BMI). As of now, various medications are being investigated and vaccine trials have been initiated by numerous countries. Before being able to find the most effective treatment, protecting, diminishing exposure, securing, and insulating our healthcare workers from possible infection is the biggest challenge to safeguard the health of our patients. We hope that this innovative “aerosol box” design can provide an extra layer of protection to clinicians performing high-risk procedures.

Candidate genes and gene markers for the resistance to porcine pleuropneumonia

Actinobacillus (A.) pleuropneumoniae is one of the most important respiratory pathogens in global pig production. Antimicrobial treatment and vaccination provide only limited protection, but genetic disease resistance is a very promising alternative for sustainable prophylaxis. Previous studies have discovered multiple QTL that may explain up to 30% of phenotypic variance. Based on these findings, the aim of the present study was to use genomic sequencing to identify genetic markers for resistance to pleuropneumonia in a segregating commercial German Landrace line. 163 pigs were infected with A. pleuropneumoniae Serotype 7 through a standardized aerosol infection method. Phenotypes were accurately defined on a clinical, pathological and microbiological basis. The 58 pigs with the most extreme phenotypes were genotyped by sequencing (next-generation sequencing). SNPs were used in a genome-wide association study. The study identified genome-wide associated SNPs on three chromosomes, two of which were chromosomes of QTL which had been mapped in a recent experiment. Each variant explained up to 20% of the total phenotypic variance. Combined, the three variants explained 52.8% of the variance. The SNPs are located in genes involved in the pathomechanism of pleuropneumonia. This study confirms the genetic background for the host’s resistance to pleuropneumonia and indicates a potential role of three candidates on SSC2, SSC12 and SSC15. Favorable gene variants are segregating in commercial populations. Further work is needed to verify the results in a controlled study and to identify the functional QTN.

Flow Cytometry Analysis and Fluorescence-activated Cell Sorting of Myeloid Cells from Lung and Bronchoalveolar Lavage Samples from Mycobacterium tuberculosis-infected Mice.

Mycobacterium tuberculosis (Mtb) is transmitted by aerosol and can cause serious bacterial infection in the lung that can be fatal if left untreated. Mtb is now the leading cause of death worldwide by an infectious agent. Characterizing the early events of in vivo infection following aerosol challenge is critical for understanding how innate immune cells respond to infection but is technically challenging due to the small number of bacteria that initially infect the lung. Previous studies either evaluated Mtb-infected cells at later stages of infection when the number of bacteria in the lung is much higher or used in vitro model systems to assess the response of myeloid cells to Mtb. Here, we describe a method that uses fluorescent bacteria, a high-dose aerosol infection model, and flow cytometry to track Mtb-infected cells in the lung immediately following aerosol infection and fluorescence-activated cell sorting (FACS) to isolate naïve, bystander, and Mtb-infected cells for downstream applications, including RNA-sequencing. This protocol provides the ability to monitor Mtb-infection and cell-specific responses within the context of the lung environment, which is known to modulate the function of both resident and recruited populations. Using this protocol, we discovered that alveolar macrophages respond to Mtb infection in vivo by up-regulating a cell protective transcriptional response that is regulated by the transcription factor Nrf2 and is detrimental to early control of the bacteria.

Getting to Know SARS-CoV-2: Towards a Better Understanding of the Factors Influencing Transmission

In November 2002, a virus known as SARS-CoV was identified in Guangdong, China, and it was implicated as the etiology of severe acute respiratory syndrome. Seventeen years later, in the same month of November, a similar disease with more dramatic outcomes was identified in neighboring Wuhan. It has been six months since the identification of first cases of COVID-19 pandemic; however, unveiling clinical characteristics and modes of transmission of the disease are taking longer than expected. This overview aims to highlight some important points regarding the mode of transmission for which continuously surprising facts are being revealed every day. We also raise some vital questions to alert the scientific community to find the right answers and minimize the drastic fatal outcomes of this disease. It can be stated that SARS-CoV-2 could be transmitted as aerosol infection as well as through contacting infected surfaces. The possible role of abdominal gases as a route of spread of the virus should be considered and a fecal sample might be a useful diagnostic tool. Moreover, medical face masks are not protective from virus transmission during treating COVID-19 patients in settings where aerosol-generating procedures are performed. Doffing of PPE for healthcare workers needs more attention as this might be a source of infection unless additional measures of PPE disinfection are employed before doffing.

Herbal disinfection against Rhodococcus equi

Rhodococcus equi is an important bacterial respiratory pathogen of young foals. Prevention of R. equi depends on early detection, environmental management and chemoprophylaxis. Aerosol infection via soil is the most important route of infection to the foals and effective management of land by reducing aerosol exposure can reduce incidence of R. equi. We found that leaves of Tamarindus indica (Tamarind; Imli) and Eucalyptus globulus (Eucalyptus; Safeda) have potential in vitro antibacterial activity against R. equi. Both the plants are widely available, so leaves of these plants were tested for their disinfectant activity against R. equi present in farm soil. Study was carried out to find an herbal disinfectant for farm soil against R. equi and its active principle. Aqueous extracts of leaves of T. indica and E. globulus were fractioned on silica column by using ethanol methanol and water serially. Different fractions were tested against pure colonies of R. equi in vitro to find out active principle. To find out disinfectant property of leaves in the presence of farm soil, pure colonies of R. equi were mixed in soil and efficacy of leaves boiled water was tested against control. Water boiled with plant leaves in the concentration of 10% and above, was found effective against R. equi present in the farm soil. Active principal of T. indica was matching with the previous reports while active principle of E. globulus could not be matched with previous reports, however, it was found that active principle of E. globulus is a very polar compound.

Morphology of Naturally-Occurring Tuberculosis in Cattle Caused by Mycobacterium caprae

This study describes the pathomorphological alterations of bovine tuberculosis through gross and histopathological examinations, assessment of the distribution of lesions and the demonstration of mycobacteria. Samples from lungs, liver, small intestine, their regional lymph nodes and retropharyngeal lymph nodes were collected from 84 cattle with tuberculosis from the Allgäu, Germany. Organs were evaluated grossly, histopathologically and by transmission electron microscopy. Mycobacteria and mycobacterial antigens were demonstrated using acid-fast staining and immunohistochemistry (IHC). Bacteriological tests revealed Mycobacterium caprae in all animals. Gross alterations were classified into five patterns (I to V) with an additional pattern of acute exudative pulmonary inflammation (pattern VI). Histological lesions were classified into four types (1-4) with additional lesions occurring in lungs only. Acid-fast staining revealed a low number of bacteria in all tissues, while IHC showed comparatively more mycobacterial antigens within the lesions and also at their periphery. The alimentary tract (68%) was the main portal of entry followed by an aerosol infection (19%). It was assumed that the observed lesions reflect a continuous primary period of infection; there were no lesions typical of a secondary (post-primary) period, as reported in man and also described in the older literature on bovine tuberculosis. The broad spectrum of changes described formerly was not observed in the present cases and the route of infection and nature of acid fast staining showed differences when compared with previous studies of naturally-occurring bovine tuberculosis.

March of Mycobacterium: miRNAs intercept host cell CD40 signalling.

The disease tuberculosis is fatal if untreated. It is caused by the acid‐fast bacilli Mycobacterium tuberculosis. Mycobacterium resides and replicates within the alveolar macrophages, causing inflammation and granuloma, wherein macrophage‐T cell interactions enhance the inflammation‐causing pulmonary caseous lesions. The first interactions between Mycobacterium and the receptors on macrophages decide the fate of Mycobacterium because of phagolysosomal impairments and the expression of several miRNAs, which may regulate CD40 expression on macrophages. While the altered phagolysosomal functions impede antigen presentation to the T cell‐expressed antigen receptor, the interactions between the macrophage‐expressed CD40 and the T cell‐expressed CD40‐ligand (CD40L or CD154) provide signals to T cells and Mycobacterium‐infected macrophages. These two functions significantly influence the resolution or persistence of Mycobacterium infection. CD40 controls T‐cell polarisation and host‐protective immunity by eliciting interleukin‐12p40, nitric oxide, reactive oxygen species and IFN‐γ production. Indeed, CD40‐deficient mice succumb to low‐dose aerosol infection with Mycobacterium because of deficient interleukin (IL)‐12 production leading to impaired IFN‐γ‐secreting T‐cell response. In contrast, despite generating fewer granulomas, the CD40L‐deficient mice developed anti‐mycobacterial T‐cell responses to the levels observed in the wild‐type mice. These host‐protective responses are significantly subdued by the Mycobacterium‐infected macrophage produced TGF‐β and IL‐10, which promote pro‐mycobacterial T‐cell responses. The CD40‐CD40L‐induced counteractive immune responses against Mycobacterium thus present a conundrum that we explain here with a reconciliatory hypothesis. Experimental validation of the hypothesis will provide a rationale for designing anti‐tubercular immunotherapy.

Review of SARS-CoV-2 and Conjunctivitis: Ophthalmologists Be Safe

The COVID-19 or the Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) has become pandemic with its origin in Wuhan, city of China. Within few weeks, it became a global health threat involving more than 200 countries. Though the main route of transmission is by respiratory droplets; trans-conjunctival aerosol infection is a known mode of disease transmission. Patients with COVID-19 conjunctivitis have the transmissible virus in the tears. Close contact during ophthalmic procedures poses the risk of patient to ophthalmologist disease transmission. Conjunctivitis may be the first symptom of COVID-19. In context to this and the close proximity of an ophthalmologist and Health Care Workers (HCW) with the patient, and the nature of work, standard infection protection measures guidelines have been given by prominent healthcare societies.

Environmental Conditioning and Aerosol Infection of Mice.

Influenza infection models in mice are widely used to study flu-mediated immune responses and pathology. However, most laboratory mice are housed at 20 °C and 50% relative humidity (RH). To better recapitulate influenza epidemics and immune responses during winter seasons, mice were housed at 20 °C under different humidity conditions, 10-20% or 50% RH. Here, we describe a protocol for using aerosolized droplets to infect mice with influenza under different environmental conditions. Using this method enables influenza infection studies performed under more physiologically relevant conditions which better mimics human viral exposure.

Pathologic changes and immune responses against Coxiella burnetii in mice following infection via non-invasive intratracheal inoculation.

Q fever is a worldwide zoonosis caused by Coxiella burnetii. Human Q fever is typically acquired through inhalation of contaminated aerosols, resulting in an initial pulmonary infection. In this study, BALB/c mice were infected with C. burnetii via an intratracheal (IT) route using a non-invasive aerosol pulmonary delivery device to directly place the living C. burnetii organisms into the lungs of the mice. The bacterial loads, pathological lesions, and antibody and cellular responses were analyzed and compared with those of mice infected via an intraperitoneal (IP) route. Compared with mice infected via an IP route, mice infected via an IT route exhibited a higher bacterial load and more severe pathological lesions in the heart and lungs at days 3 and 7 post-infection (pi). The levels of interferon-γ and IL-12p70 in the serum of mice infected via the IT route were significantly higher than those of mice infected via the IP route at day 3 pi. In conclusion, this murine model of acute C. burnetii infection via IT inoculation closely resembles the natural route of C. burnetii infection than that of IP injection. Thus, this newly developed model will be useful for investigating the pathogenesis and immunity of C. burnetii aerosol infection, as well as for the evaluation of therapeutic drugs and preventive vaccines of Q fever.

Biomarkers of cell-mediated immunity to bovine tuberculosis

Whole blood based assays, particularly interferon gamma (IFN-γ) release assays (IGRAs), are used for the diagnosis of both bovine and human tuberculosis (TB). The aim of the current study was to evaluate a panel of cytokines and chemokines for potential use as diagnostic readouts indicative of Mycobacterium bovis (M. bovis) infection in cattle. A gene expression assay was used to determine the kinetics of the response to M. bovis purified protein derivative and a fusion protein consisting of ESAT-6, CFP10, and Rv3615c upon aerosol infection with ∼104 cfu of M. bovis. The panel of biomarkers included: IFN-γ, CXCL9, CXCL10, CCL2, CCL3, TNF-α, IL-1α, IL-1β, IL-1Ra, IL-22, IL-21 and IL-13. Protein levels of IFN-γ, CXCL9, and CXCL10 were determined by ELISA. Findings suggest that CXCL9, CXCL10, IL-21, IL-13, and several acute phase cytokines may be worth pursuing as diagnostic biomarkers of M. bovis infection in cattle.

Coxiella burnetii Intratracheal Aerosol Infection Model in Mice, Guinea Pigs, and Nonhuman Primates.

Coxiella burnetii, the etiological agent of Q fever, is a Gram-negative bacterium transmitted to humans by inhalation of contaminated aerosols. Acute Q fever is often self-limiting, presenting as a febrile illness that can result in atypical pneumonia. In some cases, Q fever becomes chronic, leading to endocarditis that can be life threatening. The formalin-inactivated whole-cell vaccine (WCV) confers long-term protection but has significant side effects when administered to presensitized individuals. Designing new vaccines against C. burnetii remains a challenge and requires the use of clinically relevant modes of transmission in appropriate animal models. We have developed a safe and reproducible C. burnetii aerosol challenge in three different animal models to evaluate the effects of pulmonary acquired infection. Using a MicroSprayer aerosolizer, BL/6 mice and Hartley guinea pigs were infected intratracheally with C. burnetii Nine Mile phase I (NMI) and demonstrated susceptibility as determined by measuring bacterial growth in the lungs and subsequent dissemination to the spleen. Histological analysis of lung tissue showed significant pathology associated with disease, which was more severe in guinea pigs. Infection using large-particle aerosol (LPA) delivery was further confirmed in nonhuman primates, which developed fever and pneumonia. We also demonstrate that vaccinating mice and guinea pigs with WCV prior to LPA challenge is capable of eliciting protective immunity that significantly reduces splenomegaly and the bacterial burden in spleen and lung tissues. These data suggest that these models can have appreciable value in using the LPA delivery system to study pulmonary Q fever pathogenesis as well as designing vaccine countermeasures to C. burnetii aerosol transmission.

The characteristics of hDPP4 transgenic mice subjected to aerosol MERS coronavirus infection via an animal nose-only exposure device.

BackgroundMiddle East respiratory syndrome coronavirus (MERS‐CoV), which is not fully understood in regard to certain transmission routes and pathogenesis and lacks specific therapeutics and vaccines, poses a global threat to public health.MethodsTo simulate the clinical aerosol transmission route, hDPP4 transgenic mice were infected with MERS‐CoV by an animal nose‐only exposure device and compared with instillation‐inoculated mice. The challenged mice were observed for 14 consecutive days and necropsied on days 3, 5, 7, and 9 to analyze viral load, histopathology, viral antigen distribution, and cytokines in tissues.ResultsMERS‐CoV aerosol‐infected mice with an incubation period of 5‐7 days showed weight loss on days 7‐11, obvious lung lesions on day 7, high viral loads in the lungs on days 3‐9 and in the brain on days 7‐9, and 60% survival. MERS‐CoV instillation‐inoculated mice exhibited clinical signs on day 1, obvious lung lesions on days 3‐5, continuous weight loss, 0% survival by day 5, and high viral loads in the lungs and brain on days 3‐5. Viral antigen and high levels of proinflammatory cytokines and chemokines were detected in the aerosol and instillation groups. Disease, lung lesion, and viral replication progressions were slower in the MERS‐CoV aerosol‐infected mice than in the MERS‐CoV instillation‐inoculated mice.ConclusionhDPP4 transgenic mice were successfully infected with MERS‐CoV aerosols via an animal nose‐only exposure device, and aerosol‐ and instillation‐infected mice simulated the clinical symptoms of moderate diffuse interstitial pneumonia. However, the transgenic mice exposed to aerosol MERS‐CoV developed disease and lung pathology progressions that more closely resembled those observed in humans.

1885. T-helper 1 (Th1) Production of Interferon Gamma (IFNγ) Is Directly Inhibited by TGFβ Within Pulmonary Mycobacterium tuberculous (Mtb) Granulomas

BackgroundCD4 T-cell production of IFNɣ is essential to prevent dissemination of pulmonary Mtb, though is less effective at controlling infection within the lung. Because T cells are most effective in the context of direct interactions with Mtb-infected cells, we sought to determine the location of CD4 T-cell antigen sensing and IFNɣ production within granulomas.MethodsWe used a murine ultra-low-dose aerosol infection, developed by our lab, where most mice are infected by a single bacillus, resulting in a solitary granuloma that is more similar to human granulomas. We examined the lungs of wild-type mice 35 days later for patterns of T-cell activation with quantitative confocal imaging. This analysis was next performed following adoptive co-transfer of Th1 polarized Mtb-specific cells and control cells of irrelevant specificity (OVA). To determine the effect of TGFβ on IFNɣ production, we examined mice that lack the TGFβR on T cells (TGFβR.KO). Finally, we examined whether this effect was Th1 cell-intrinsic with an adoptive transfer of Th1-polarized Mtb-specific cells with (Tg.WT) and without (Tg.KO) the TGFβR.ResultsDespite many CD4 T cells localizing to the granuloma and undergoing T-cell receptor (TCR) activation (pS6), IFNɣ production was not significantly increased in the granuloma compared with a distal lung site (Figure 1). This pattern of localization and activation was found to be similar in the Mtb-specific (but not control) Th1 cells (Figure 2). In contrast, CD4 T cells from TGFβR.KO mice produced more IFNɣ within the granuloma (Figure 3). Lastly, Tg.KO cells transferred into wild-type mice produced increased IFNɣ compared with Tg.WT, mirroring the findings in TGFβR.KO mice (Figure 4).ConclusionCD4 T cell production of IFNɣ is decreased within the granuloma, where it can be most effective, despite evidence of ongoing TCR stimulation in Mtb-specific cells. We have shown that by alleviating the effects of TGFβ signaling, even terminally-differentiated Mtb-specific Th1 cells can produce more IFNɣ within the granuloma. While this modest increase suggests that there are additional mechanisms at play which warrant further exploration, these findings have the potential to guide immunotherapeutic development, especially given that TGFβ inhibitors are already in phase III clinical trials for other purposes. Disclosures All Authors: No reported Disclosures.