Aerosol Inoculation Research Articles

Low Dose Aerosol Fitness at the Innate Phase of Murine Infection Better Predicts Virulence amongst Clinical Strains of Mycobacterium tuberculosis

BackgroundEvaluation of a quick and easy model to determine the intrinsic ability of clinical strains to generate active TB has been set by assuming that this is linked to the fitness of Mycobacterium tuberculosis strain at the innate phase of the infection. Thus, the higher the bacillary load, the greater the possibility of inducting liquefaction, and thus active TB, once the adaptive response is set.Methodology/Principal FindingsThe virulence of seven clinical Mycobacterium tuberculosis strains isolated in Spain was tested by determining the bacillary concentration in the spleen and lung of mice at weeks 0, 1 and 2 after intravenous (IV) inoculation of 104 CFU, and by determining the growth in vitro until the stationary phase had been reached. Cord distribution automated analysis showed two clear patterns related to the high and low fitness in the lung after IV infection. This pattern was not seen in the in vitro fitness tests, which clearly favored the reference strain (H37Rv). Subsequent determination using a more physiological low-dose aerosol (AER) inoculation with 102 CFU showed a third pattern in which the three best values coincided with the highest dissemination capacity according to epidemiological data.Conclusions/SignificanceThe fitness obtained after low dose aerosol administration in the presence of the innate immune response is the most predictive factor for determining the virulence of clinical strains. This gives support to a mechanism of the induction of active TB derived from the dynamic hypothesis of latent tuberculosis infection.

Experimental Aerosol Inoculation and Investigation of Potential Lateral Transmission ofMycobacterium bovisin Virginia Opossum (Didelphis virginiana)

An endemic focus of Mycobacterium bovis (M. bovis) infection in the state of Michigan has contributed to a regional persistence in the animal population. The objective of this study was to determine if Virginia opossums (Didelphis virginiana) contribute to disease persistence by experimentally assessing intraspecies lateral transmission. One wild caught pregnant female opossum bearing 11 joeys (young opossum) and one age-matched joey were obtained for the study. Four joeys were aerosol inoculated with M. bovis (inoculated), four joeys were noninoculated (exposed), and four joeys plus the dam were controls. Four replicate groups of one inoculated and one exposed joey were housed together for 45 days commencing 7 days after experimental inoculation. At day 84 opossums were sacrificed. All four inoculated opossums had a positive test band via rapid test, culture positive, and gross/histologic lesions consistent with caseogranulomatous pneumonia. The exposed and control groups were unremarkable on gross, histology, rapid test, and culture. In conclusion, M. bovis infection within the inoculated opossums was confirmed by gross pathology, histopathology, bacterial culture, and antibody tests. However, M. bovis was not detected in the control and exposed opossums. There was no appreciable lateral transmission of M. bovis after aerosol inoculation and 45 days of cohabitation between infected and uninfected opossums.

The re-emergence of measles in developed countries: Time to develop the next-generation measles vaccines?

The re-emergence of measles in developed countries: Time to develop the next-generation measles vaccines?

Increasing the Time of Exposure to Aerosol Measles Vaccine Elicits an Immune Response Equivalent to That Seen in 9-Month-Old Mexican Children Given the Same Dose Subcutaneously

A 30-second aerosol measles vaccination successfully primes children 12 months of age and older but is poorly immunogenic when given to 9-month-old children. We examined the immune responses when increasing the duration to aerosol exposure in 9-month-olds. One hundred and thirteen healthy 9-month-old children from Mexico City were enrolled; 58 received aerosol EZ measles vaccine for 2.5 minutes and 55 subcutaneously. Measles-specific neutralizing antibodies and cellular responses were measured before and at 3 and 6 months postimmunization. Adaptive immunity was induced in 97% after aerosol and 98% after subcutaneous administration. Seroconversion rates and GMCs were 95% and 373 mIU/mL (95% confidence interval [CI], 441-843) following aerosol vaccination and 91% and 306 mIU/mL (95% CI, 367-597) after subcutaneous administration at 3 months. The percentage of children with a measles-specific stimulation index ≥3 was 45% and 60% in the aerosol versus 55% and 59% in the subcutaneous group at 3 and 6 months, respectively. CD8 memory cell frequencies were higher in the aerosol group at 3 months compared with the subcutaneous group. Adverse reactions were comparable in both groups. Increasing exposure time to aerosol measles vaccine elicits immune responses that are comparable to those seen when an equivalent dose is administered by the subcutaneous route in 9-month-old infants.

A lack of antibody formation against inactivated influenza virus after aerosol vaccination in presence or absence of adjuvantia

In the poultry industry, infections with avian influenza virus (AIV) can result in significant economic losses. The risk and the size of an outbreak might be restricted by vaccination of poultry. A vaccine that would be used for rapid intervention during an outbreak should be safe to use, highly effective after a single administration and be suitable for mass application. A vaccine that could be applied by spray or aerosol would be suitable for mass application, but respiratory applied inactivated influenza is poorly immunogenic and needs to be adjuvanted. We chose aluminum OH, chitosan, cholera toxin B subunit (CT-B), and Stimune as adjuvant for an aerosolized vaccine with inactivated H9N2. Each adjuvant was tested in two doses. None of the adjuvanted vaccines induced AIV-specific antibodies after single vaccination, measured 1 and 3 weeks after vaccination by aerosol, in contrast to the intramuscularly applied vaccine. The aerosolized vaccine did enter the chickens’ respiratory tract as CT-B-specific serum antibodies were detected after 1 week in chickens vaccinated with the CT-B-adjuvanted vaccine. Chickens showed no adverse effects after the aerosol vaccination based on weight gain and clinical signs. The failure to detect AIV-specific antibodies might be due to the concentration of the inactivated virus.

Bacillus cereus G9241 Makes Anthrax Toxin and Capsule like Highly Virulent B. anthracis Ames but Behaves like Attenuated Toxigenic Nonencapsulated B. anthracis Sterne in Rabbits and Mice

Bacillus cereus G9241 was isolated from a welder with a pulmonary anthrax-like illness. The organism contains two megaplasmids, pBCXO1 and pBC218. These plasmids are analogous to the Bacillus anthracis Ames plasmids pXO1 and pXO2 that encode anthrax toxins and capsule, respectively. Here we evaluated the virulence of B. cereus G9241 as well as the contributions of pBCXO1 and pBC218 to virulence. B. cereus G9241 was avirulent in New Zealand rabbits after subcutaneous inoculation and attenuated 100-fold compared to the published 50% lethal dose (LD(50)) values for B. anthracis Ames after aerosol inoculation. A/J and C57BL/6J mice were comparably susceptible to B. cereus G9241 by both subcutaneous and intranasal routes of infection. However, the LD(50)s for B. cereus G9241 in both mouse strains were markedly higher than those reported for B. anthracis Ames and more like those of the toxigenic but nonencapsulated B. anthracis Sterne. Furthermore, B. cereus G9241 spores could germinate and disseminate after intranasal inoculation into A/J mice, as indicated by the presence of vegetative cells in the spleen and blood of animals 48 h after infection. Lastly, B. cereus G9241 derivatives cured of one or both megaplasmids were highly attenuated in A/J mice. We conclude that the presence of the toxin- and capsule-encoding plasmids pBCXO1 and pBC218 in B. cereus G9241 alone is insufficient to render the strain as virulent as B. anthracis Ames. However, like B. anthracis, full virulence of B. cereus G9241 for mice requires the presence of both plasmids.

An evaluation of respiratory administration of measles vaccine for prevention of acute lower respiratory infections in children

BackgroundMeasles was responsible for an estimated 100,000 deaths worldwide in 2008. Despite being a vaccine-preventable disease, measles remains a major cause of morbidity and mortality in young children. Although a safe and effective injectable measles vaccine has been available for over 50 years it has not been possible to achieve the uniformly high levels of coverage (required to achieve measles eradication) in most parts of the developing world. Aerosolised measles vaccines are now under development with the hope of challenging the delivery factors currently limiting the coverage of the existing vaccine.MethodsWe used a modified CHNRI methodology for setting priorities in health research investments to assess the strengths and weaknesses of this emerging intervention to decrease the burden of childhood pneumonia. This was done in two stages. In Stage I, we systematically reviewed the literature related to emerging aerosol vaccines against measles relevant to several criteria of interest. Although there are a number of different aerosol vaccine approaches under development, for the purpose of this exercise, all were considered as one intervention. The criteria of interest were: answerability; cost of development, production and implementation; efficacy and effectiveness; deliverability, affordability and sustainability; maximum potential impact on disease burden reduction; acceptability to the end users and health workers; and effect on equity. In Stage II, we conducted an expert opinion exercise by inviting 20 experts (leading basic scientists, international public health researchers, international policy makers and representatives of pharmaceutical companies). The policy makers and industry representatives accepted our invitation on the condition of anonymity, due to the sensitive nature of their involvement in such exercises. They answered questions from the CHNRI framework and their “collective optimism” towards each criterion was documented on a scale from 0 to 100%.ResultsThe panel of experts expressed mixed feelings about an aerosol measles vaccine. The group expressed low levels of optimism regarding the criteria of likelihood of efficacy and low cost of development (scores around 50%); moderate levels of optimism regarding answerability, low cost of production, low cost of implementation and affordability (score around 60%); and high levels of optimism regarding deliverability, impact on equity and acceptability to health workers and end-users (scores over 80%). Finally, the experts felt that this intervention will have a modest but nevertheless important impact on reduction of burden of disease due to childhood pneumonia (median: 5%, interquartile range 1-15%, minimum 0%, maximum 45%).ConclusionAerosol measles vaccine is at an advanced stage of development, with evidence of good immunogenicity. This new intervention will be presented as a feasible candidate strategy in the campaign for global elimination of measles. It also presents an unique opportunity to decrease the overall burden of disease due to severe pneumonia in young children.

Present status of nanoparticle research for treatment of Tuberculosis

Nanotechnology has offered enormous improvement in field of therapeutics by means of designing of drug delivery systems and opened the possibility of controlling infections at the molecular level. Nanocarriers can cross biological barriers and are able to target cellular reservoirs of Mycobacterium tuberculosis (M. tuberculosis). Nanoparticle-based systems have significant potential for treatment and prevention of tuberculosis (TB). A variety of nanocarriers have been widely evaluated as potential drug delivery systems for various administration routes. Targeting the drugs to certain physiological sites such as the lymph nodes has emerged as a promising strategy in treating TB with improved drug bioavailability and reduction of the dosing frequency. Nanotechnology based rational targeting may improve therapeutic success by limiting adverse drug effects and requiring less frequent administration regimes, ultimately resulting in more patients compliance and thus attain higher adherence levels. The development of nanoparticle based aerosol vaccine is undergoing which could serve as new platform for immunization. Present article compiles the general physiological aspects of the infection along with the relevance nanocarriers used in prevention of tuberculosis.

Aerosol Inoculation with a Sub-lethal Influenza Virus Leads to Exacerbated Morbidity and Pulmonary Disease Pathogenesis

A mouse model has been extensively used to investigate disease intervention approaches and correlates of immunity following influenza virus infection. The majority of studies examining cross-reactive and protective immune responses have used intranasal (IN) virus inoculation; however, infectious aerosols are a common means of transmitting influenza in the human population. In this study, IN and aerosol routes of inoculation were compared and end-points of immunity and disease pathogenesis were evaluated in mice using mouse-adapted H3N2 A/Aichi/2/68 (x31). Aerosol inoculation with sub-lethal x31 levels caused more robust infection, which was characterized by enhanced morbidity, mortality, pulmonary cell infiltration, and inflammation, compared to IN-inoculated mice, as well as higher levels of IL-6 expression in the lung. Treatment with IL-6-blocking antibodies reduced pulmonary infiltrates and lung pathology in aerosol-inoculated mice. This study shows that aerosol inoculation results in a distinctive host response and disease outcome compared to IN inoculation, and suggests a possible role for IL-6 in lung pathogenesis.

Novel Formulation Concept for Particulate Uptake of Vaccines via the Nasal Associated Lymphoid Tissue

Aerosol vaccination via the mucosa targets an epithelium critical to host defence against inhaled pathogens, potentially avoids needle injection, and provides an exciting opportunity in the development of stable dry powder vaccine formulations. Specialised cells in the mucosa are able to take up and guide antigens directly to immune cells. In contrast to soluble antigen formulations, particles with antigen also provoke a local sIgA mediated immune response before being presented to the systemic immune system. In this study, particles containing the model antigen BSA and chitosan as stabiliser with adjuvant activity are produced by spray drying. The compatibility and uptake of these particles via the respiratory epithelium is determined in vitro on Calu-3 cells. The in vitro deposition studies are performed in a nasal cast made from CT scan data using a novel nasal dry powder device. The deposition profile is optimised by the use of interactive mixtures with a low separation capacity. The spray drying process results in spherical particles with a size in the low micrometer range (x50 3μm), which are well tolerated when administered to the cells and which are readily taken up. As the particles have to be big enough to be retained in the appropriate place in the respiratory tract (e.g. the nasal cavity) to be taken up efficiently, the primary particles are too small. Deposition studies show a high fraction of almost 56% transiting the nose and being capable of inhalation. This fraction can be reduced by utilising an interactive mixture with a carrier, where only 5% of the antigen carrying particles leave the nasal cavity. Particulate vaccine formulations are a promising formulation approach for mucosal vaccination targeting the nasal mucosa. With small antigen carrying particles immobilised on carrier particles, the antigen is delivered exclusively to the nose.

An overview of rabies - history, epidemiology, control and possible elimination.

Rabies remains the most important zoonotic disease in many countries. Public concern and fears are most focused on dogs as the source of rabies infection to humans and other domestic animals. Several bat species are reservoir hosts of rabies and therefore can be a public health hazard. The possibility of a carrier state or asymptomatic form of rabies deserves serious evaluation. Rabies in most countries was successfully controlled through mass vaccination of dogs, long before the recognition of bat and other wildlife rabies and the availability of modern vaccines. Though, the epidemiology, virology, transmission, pathology, clinical manifestations, diagnosis, treatment and control of rabies infection have been described extensively, the incidence is increasingly on the high side. However, experts have recognized for decades that rabies is wholly eradicable from all species except bats through targeted mass immunization, and the chief obstacle to eradicating rabies especially in bats is that no one has developed an aerosolized vaccine that could be sprayed into otherwise inaccessible caves and tree trunks. Inventing such a vaccine is considered difficult but possible. Forestalling this problem will require active epidemiological surveillance of wild and domestic animals with a wide range of modern molecular and ancillary epidemiological tools. This also demands government and private sector intervention, funding and collaboration of professionals in human and veterinary medicine with those in the environmental sciences. Recently, the heroic recovery of an unvaccinated teenager from clinical rabies offers hope of future specific therapy. While post-exposure vaccination is essential and should be continued with improvement to achieve consistently positive results, progress toward eliminating rabies has been markedly faster in nations that have emphasized preventive vaccination of animals. Key words: Control, epidemiology, history, mass vaccination, surveillance, zoonotic disease.

High infectivity and pathogenicity of influenza A virus via aerosol and droplet transmission

Influenza virus may be transmitted through the respiratory route by inhalation of an aerosol of non-sedimenting droplets, or by deposition of sedimenting droplets in the upper respiratory tract. Whichever of these is the predominant route for infection with influenza virus has been subject of continuing debate, resulting in detailed studies of aerosol versus droplet exposure. A decisive knowledge gap preventing a satisfying conclusion is absence of a well defined human dose response model for influenza virus. This study uses a hierarchical approach generalizing over twelve human challenge studies collected in a literature search. Distinction is made between aerosol and intranasal inoculation. The results indicate high infectivity via either route, but intranasal inoculation leads to about 20 times lower infectivity than when the virus is delivered in an inhalable aerosol. A scenario study characterizing exposure to airborne virus near a coughing infected person in a room with little ventilation demonstrates that with these dose response models the probabilities of infection by either aerosol or sedimenting droplets are approximately equal. Droplet transmission results in a slightly higher illness risk due to the higher doses involved. Establishing a dose response model for influenza provides a firm basis for studies of interventions reducing exposure to different classes of infectious particles. More studies are needed to clarify the role of different modes of transmission in other settings.

Animal Models of Orthopoxvirus Infection

Smallpox was one of the most devastating diseases known to humanity. Although smallpox was eradicated through a historically successful vaccination campaign, there is concern in the global community that either Variola virus (VARV), the causative agent of smallpox, or another species of Orthopoxvirus could be used as agents of bioterrorism. Therefore, development of countermeasures to Orthopoxvirus infection is a crucial focus in biodefense research, and these efforts rely on the use of various animal models. Smallpox typically presented as a generalized pustular rash with 30 to 40% mortality, and although smallpox-like syndromes can be induced in cynomolgus macaques with VARV, research with this virus is highly restricted; therefore, animal models with other orthopoxviruses have been investigated. Monkeypox virus causes a generalized vesiculopustular rash in rhesus and cynomolgus macaques and induces fatal systemic disease in several rodent species. Ectromelia virus has been extensively studied in mice as a model of orthopoxviral infection in its natural host. Intranasal inoculation of mice with some strains of vaccinia virus produces fatal bronchopneumonia, as does aerosol or intranasal inoculation of mice with cowpox virus. Rabbitpox virus causes pneumonia and fatal systemic infections in rabbits and can be naturally transmitted between rabbits by an aerosol route similar to that of VARV in humans. No single animal model recapitulates all known aspects of human Orthopoxvirus infections, and each model has its advantages and disadvantages. This article provides a brief review of the Orthopoxvirus diseases of humans and the key pathologic features of animal models of Orthopoxvirus infections.

The Early Pathogenesis of Foot-and-Mouth Disease in Cattle After Aerosol Inoculation

To characterize the early events of foot-and-mouth disease virus (FMDV) infection in cattle subsequent to simulated natural exposure, 16 steers were aerosol inoculated with FMDV and euthanized at various times. Samples were collected from each steer antemortem (serum, nasal swabs, and oral swabs) and postmortem (up to 40 tissues per animal) and screened for FMDV by virus isolation and for FMDV RNA by real-time reverse transcription polymerase chain reaction. Tissues that tested positive for FMDV or viral RNA were examined by immunohistochemistry and multichannel immunofluorescence microscopy. In previremic steers, FMDV was most consistently localized to nasopharyngeal tissues, thereby indicating this region as the most important site of primary viral replication. The earliest site of microscopic localization of FMDV antigens was the lymphoid follicle-associated epithelium of the pharyngeal mucosa-associated lymphoid tissue of the nasopharynx at 6 hours postaerosolization. At early time points after aerosol inoculation, viral antigens colocalized with cytokeratin-positive pharyngeal epithelial cells; intraepithelial FMDV-negative, MHCII/CD11c-double-positive dendritic cells were present in close proximity to FMDV-positive cells. Onset of viremia coincided with marked increase of viral loads in pulmonary tissues and with substantial decrease of viral detection in nasopharyngeal tissues. These data indicate that subsequent to aerogenous exposure to FMDV, the temporally defined critical pathogenesis events involve (1) primary replication in epithelial cells of the pharyngeal mucosa-associated lymphoid tissue crypts and (2) subsequent widespread replication in pneumocytes in the lungs, which coincides with (3) the establishment of sustained viremia.

The region between the two polyprotein initiation codons of foot-and-mouth disease virus is critical for virulence in cattle

To explore the role in viral pathogenesis of the region located between the two functional AUG (inter-AUG) in foot-and-mouth disease virus (FMDV), we derived viruses containing transposon (tn) inserts from a mutagenized cDNA infectious clone of FMDV (pA24-WT). Mutant viruses containing an in-frame 57-nt transposon insertion grew at a slower rate and had a smaller plaque size phenotype than the parental virus (A24-WT). A mutant virus containing a 51-nt deletion in inter-AUG had a similar phenotype in cell culture to that of A24-WT. When tested by aerosol inoculation in cattle (3 animals per virus), the deletion mutant was fully virulent as was A24-WT. Mutant viruses containing insertions in inter-AUG did not cause clinical disease or viremia. However, viruses that partially or totally removed the tn insertion during animal infection reverted to virulence in 2 inoculated steers. Therefore, this study identified inter-AUG as an FMDV viral virulence determinant in cattle infected by aerosol route.

Induction of mucosal and systemic antibody responses against the HIV coreceptor CCR5 upon intramuscular immunization and aerosol delivery of a virus-like particle based vaccine

Virus-like particles (VLPs) can be exploited as platforms to increase the immunogenicity of poorly immunogenic antigens, including self-proteins. We have developed VLP-based vaccines that target two domains of the HIV coreceptor CCR5 that are involved in HIV binding. These vaccines induce anti-CCR5 antibodies that bind to native CCR5 and inhibit SIV infection in vitro. Given the role of mucosal surfaces in HIV transmission and replication, we also asked whether an aerosolized, VLP-based pulmonary vaccine targeting CCR5 could induce a robust mucosal response in addition to a systemic response. In rats, both intramuscular and pulmonary immunization induced high-titer IgG and IgA against the vaccine in the serum, but only aerosol vaccination induced IgA antibodies at local mucosal sites. An intramuscular prime followed by an aerosol boost resulted in strong serum and mucosal antibody responses. These results show that VLP-based vaccines targeting CCR5 induce high-titer systemic antibodies, and can elicit both local and systemic mucosal response when administered via an aerosol. Vaccination against a self-molecule that is critically involved during HIV transmission and pathogenesis is an alternative to targeting the virus itself. More generally, our results provide a general method for inducing broad systemic and mucosal antibody responses using VLP-based immunogens.

Aerosol infectivity of a Baculovirus toTrichoplusia nilarvae: An alternative larval inoculation strategy for recombinant protein production

The baculovirus-insect expression system is a popular tool for recombinant protein production. The standard method for infecting insect larvae with recombinant baculovirus for protein production involves either feeding occlusion bodies or injecting budded virus into the cuticle. In this study, we showed that the recombinant Autographa californica multiple nucleopolyhedrovirus (AcMNPV) at titers >10(8) pfu/mL efficiently infected Trichoplusia ni (T. ni) larvae through aerosol inoculation of budded virus at a pressure of 5.5 x 10(4) Pa. The dipping T. ni larvae in virus-containing solution efficiently infected them. These results indicate that surface contamination, either by aerosol or dipping, lead to infection via spiracles. The aerosol infection route for AcMNPV was restricted to T. ni and Plutella xylostella larvae, whereas Spodoptera litura and Helicoverpa armigera larvae were resistant to this inoculation process. The yields of the reporter proteins DsRed and EGFP from T. ni larvae following aerosol infection were nearly identical to those following oral feeding or injection. This alternative baculovirus infection strategy facilitates recombinant protein and virus production by insect larvae.

T Cells from Lungs and Livers ofFrancisella tularensis-Immune Mice Control the Growth of Intracellular Bacteria

Parenteral and respiratory vaccinations with the intracellular bacterium Francisella tularensis have been studied using the live vaccine strain (LVS) in a mouse model, and spleen cells from immune mice are often used for immunological studies. However, mechanisms of host immunological responses may be different in nonlymphoid organs that are important sites of infection, such as lung and liver. Using parenteral (intradermal) or respiratory (cloud aerosol) vaccination, here we examine the functions of resulting LVS-immune liver or lung cells, respectively. Surprisingly, LVS was considerably more virulent when administered by cloud aerosol than by intranasal instillation, suggesting method-dependent differences in initial localization and/or dissemination patterns. Only low doses were sublethal, and resolution of sublethal cloud aerosol infection was dependent on gamma interferon (IFN-gamma), tumor necrosis factor alpha, and inducible nitric oxide synthase. Nonetheless, survival of cloud aerosol or parenteral infection resulted in the development of a protective immune response against lethal LVS intraperitoneal or aerosol challenge, reflecting development of systemic secondary immunity in both cases. Such immunity was further detected by directly examining the functions of LVS-immune lung or liver lymphocytes in vitro. Lung lymphocytes primed by respiratory infection, as well as liver lymphocytes primed by parenteral infection, clearly controlled in vitro intracellular bacterial growth primarily via mechanisms that were not dependent on IFN-gamma activity. Thus, our results indicate functional similarities between immune T cells residing in spleens, livers, and lungs of LVS-immune mice.

Early events in the pathogenesis of foot-and-mouth disease in cattle after controlled aerosol exposure

The goal of this study was to identify the primary sites of replication of foot-and-mouth disease virus (FMDV) in cattle subsequent to aerogenous inoculation. A novel aerosol inoculation method was developed to simulate natural, airborne transmission and thereby allow the identification of early replication sites. Virus distribution after aerosol inoculation was compared at 24h post inoculation with simple nasal instillation. Aerosol inoculation of FMDV consistently resulted in virus detection by real-time reverse transcriptase-polymerase chain reaction and viral isolation in the soft palate, pharynx, and lungs. Viral antigen was also detected in each of these tissues by immunohistochemistry. Aerosol exposure resulted in typical clinical signs of FMD when animals were kept alive long enough to develop disease. This aerosol infection method is highly reproducible regarding inoculum dose and volume, and allowed the detailed study of early events in FMDV-infected cattle. Extensive postmortem sampling and trimodal virus detection system allows a more precise determination of FMDV localization than previously reported.

Vaccination of broiler chickens with dispersed dry powder vaccines as an alternative for liquid spray and aerosol vaccination

Vaccination of chickens with dispersable dry powder vaccines was compared with commercial liquid vaccines. A Clone 30 Newcastle disease vaccine virus was spray dried with mannitol or with a mixture of trehalose, polyvinylpyrrolidone and bovine serum albumin. A coarse (±30 μm) and fine (±7 μm) powder were produced with both formulations. A commercial reconstituted Clone 30 vaccine was applied as coarse liquid spray (±222 μm) or fine liquid aerosol (±24 μm). Reduction of virus concentration in the air after dispersion/nebulization was monitored by air sampling and was explained by sedimentation of coarse particles/droplets and evaporation of fine droplets. The vaccine formulations induced high haemagglutination inhibition antibody titres in the serum of 4-week-old broilers (2 7 at 4 weeks post-vaccination). The good serum antibody response with the fine liquid aerosol despite extensive inactivation of virus due to evaporation of droplets, suggested that powder formulations (without inactivation due to evaporation) might allow a significant reduction of vaccine dose, thereby offering new options for fine aerosol vaccination with low-titre vaccines.