PULMONARY EDEMA IN INFLUENZAL PNEUMONIA OF THE MOUSE AND THE RELATION OF FLUID IN THE LUNG TO THE INCEPTION OF PNEUMOCOCCAL PNEUMONIA

Pulmonary edema is a component of the fully developed influenza viral lesion in the mouse. Mice with experimental pulmonary fluid have an increased susceptibility to inhaled pneumococci and under these circumstances the organisms grow in the lung and produce the lesion of bacterial pneumonia. The presence of pulmonary edema in the lesion due to the influenza virus in the lung of the mouse appears to account adequately for the previous observation that inhaled pneumococci grow in the influenza viral lesion. Mice dying of pneumococcal septicemia after inhaling fine droplets containing this organism do not have pneumonia. The delay in migration of polymorphonuclear leucocytes into the lung after injection of pneumococci suspended in serum is an important factor in susceptibility to infection since it allows ample time for pneumococci to grow in the pulmonary fluid. The slow phagocytic action of pulmonary macrophages likewise permits growth of pneumococci. Conditions in human beings that are known to be complicated by pulmonary edema are also known to be associated with increased susceptibility to secondary bacterial pneumonia

EFFECT OF INFLUENZA VIRUS ON CILIA AND EPITHELIAL CELLS IN THE BRONCHI OF MICE

In order to determine the effect of infection with influenza virus on bronchial cilia of the mouse, ciliary beat has been visualized directly by microscopic examination of the bronchi in slices of fresh lung. Cilia have been shown also in sections of fixed tissue by the use of special silver staining methods. The results have shown persistence of the cilia in spite of severe viral infection and indicate that the lowered resistance to secondary pneumococcal infection which occurs in influenzal pneumonia of the mouse is not due to interference with the ciliary mechanism. By a process of exclusion, the findings give further support to the theory that lowered resistance to pneumococcal infection in influenzal pneumonia is due to edema fluid in the viral lesion furnishing a culture medium for inhaled pneumococci. A widely used method for evaluation of ciliary activity on respiratory epithelia has been the microscopic observation of wave-like movements in reflected light. This activity was observed readily in the bronchi of mice but evidence was obtained showing that at this site it was due to something other than ciliary beat. Further histopathologic observations were made in order to define the lesion of the bronchial epithelium that would permit sparing of ciliated cells. In addition to usual techniques, mice were injected with colchicine for estimation of the rate of cellular proliferation and were exposed to a large dose of roentgen rays to eliminate polymorphonuclear leucocytes. Stains for mucous and for mitochondria were done also. The evidence obtained favors the theory that the viral infection does not destroy any of the cells of the bronchial epithelium. Inclusion bodies were found in the cytoplasm, making it seem likely instead that viral particles grow in colony-like aggregations and that liberation of virus into the lumen takes place not only by simple extrusion of inclusions but also by detachment of inclusion-laden globular portions of the cytoplasm

INTRAPERITONEAL AND INTRACEREBRAL ROUTES IN SERUM PROTECTION TESTS WITH THE VIRUS OF EQUINE ENCEPHALOMYELITIS : III. COMPARISON OF ANTIVIRAL SERUM CONSTITUENTS FROM GUINEA PIGS IMMUNIZED WITH ACTIVE OR FORMOLIZED INACTIVE VIRUS

Earlier experiments had shown that the sera of animals immunized with active virus have much greater protective potency when serum-virus mixtures are injected intraperitoneally into 12 to 15 day old mice than when given intracerebrally. The present work was concerned with similar tests on sera derived from guinea pigs immunized by vaccines in which the virus had been inactivated by formalin. In comparing the content of antiviral body by means of intracerebral and by intraperitoneal inoculation, it was found that both sera show about the same low degree of neutralizing capacity by the former method. By intraperitoneal inoculation, on the other hand, serum collected from guinea pigs immunized by means of active virus reveals high protective power, while that from animals receiving formolized, inactive virus exhibits lower neutralization titers which approach those obtained by the intracerebral method. The significance of this unexpected finding is discussed

INTRAPERITONEAL AND INTRACEREBRAL ROUTES IN SERUM PROTECTION TESTS WITH THE VIRUS OF EQUINE ENCEPHALOMYELITIS : II. MECHANISM UNDERLYING THE DIFFERENCE IN PROTECTIVE POWER BY THE TWO ROUTES

Minute amounts of antiserum injected intraperitoneally protect against large doses of equine encephalomyelitis virus given intramuscularly or intraperitoneally in 12 to 15 day old mice. Antiserum given intraperitoneally with virus intracerebrally or intranasally results in little or no protection. These phenomena occur as well when serum-virus mixtures are injected at the different sites. The marked variation of the protective capacity of antiserum as thus displayed would appear to be dependent upon the differing pathways of progression of the virus from the site of injection to the central nervous system

INTRAPERITONEAL AND INTRACEREBRAL ROUTES IN SERUM PROTECTION TESTS WITH THE VIRUS OF EQUINE ENCEPHALOMYELITIS : I. A COMPARISON OF THE TWO ROUTES IN PROTECTION TESTS

Young (12 to 15 day old) mice are approximately as susceptible to the virus of equine encephalomyelitis, Eastern or Western strain, when it is given intraperitoneally as are adult mice when the virus is injected intracerebrally. With this susceptibility by the intraperitoneal route as a basis, the injection of immune serum-virus mixtures intraperitoneally was found to result in protection in dilutions which give rise to infection after intracerebral inoculation. The difference of protective power by the two indicated routes was shown not to depend on the amount of inoculum nor on the age of the intracerebrally injected mice. Incubation at 37°C. for 2½ hours neither increases nor diminishes the protective action of immune serum when the intraperitoneal method is employed. The phenomenon of selective protection in different tissues is elicited by the sera of hyperimmunized mice, guinea pigs, and rabbits and by sera derived from horses infected with the disease in nature or exposed to it by contact. Of four horses recovered from the malady, all showed antibody in their sera; of others exposed by contact, four of nine animals revealed antiviral bodies, when the intraperitoneal technique was employed. These tests on horse sera have pointed to the potential value of this procedure for epidemiological studies. Finally, the reaction itself has significance through its bearing on the mechanism of immunity

EFFECT OF THE LESION DUE TO INFLUENZA VIRUS ON THE RESISTANCE OF MICE TO INHALED PNEUMOCOCCI

1. The normal lung of the mouse possesses the power of reducing markedly its content of Type I pneumococci within 3 hours after inhalation of the organisms in the form of fine droplets. 2. Lungs with fully developed influenza viral pneumonia not only fail to reduce the pulmonary content of pneumococci administered in this manner but, on the contrary, support their growth. 3. After intrabronchial inoculation into mice, influenza virus multiplies rapidly in the lung within 24 hours. 4. Criteria have been established for distinction between true viral lesions of the lung and changes due to the inoculation of diluents as vehicles for the virus. 5. 24 hours after inoculation of virus, there are no macroscopic lesions in the lung and the microscopic changes are due to the diluent. 6. Presence and multiplication of the virus in the lung 24 hours after inoculation have no apparent effect on the power of the lung to reduce rapidly its content of inhaled pneumococci. 7. The effect of the virus in lowering resistance to secondary bacterial infection appears to be due to the presence of the lesion produced by the virus

ELECTRON MICROSCOPY OF HELA CELLS AFTER THE INGESTION OF COLLOIDAL GOLD

Tissue cultures of HeLa cells were grown in media containing colloidal gold, and after various intervals, the cells were fixed, embedded, and sectioned for electron microscopy. Uncoated grids with small holes were used in many of the experiments. Intracellular particles of gold were identified in areas surrounded by single membranes, in moderately dense granules, in globoid bodies, and in the cytoplasmic matrix. Gold particles were not found in typical mitochondria, Golgi complex, ergastoplasm (granular forms of endoplasmic reticulum), or nuclei. The phenomenon of pinocytosis was considered to be the most likely means by which the gold particles were ingested, and the locations of gold particles appeared to have significance concerning theories that membranous organelles of the cytoplasm may be derived from the cell membrane

ELECTRON MICROSCOPY OF EARLY CYTOPLASMIC CHANGES DUE TO INFLUENZA VIRUS

Recently improved methods for visualization of thin tissue sections by electron microscopy have been applied to the study of early changes in the bronchial epithelium of mice infected by inhalation of aerosols of influenza virus. In confirmation of previous findings by the authors, inclusion bodies have been demonstrated in ciliated and non-ciliated cells of infected bronchial epithelium. In addition to 3 strains of mouse-adapted Type A virus, 2 unadapted strains gave qualitatively the same results. The inclusion bodies were found to be composed largely of particles of a size estimated to correspond to the known size of influenza virus. The viral lesion of the cytoplasm was also associated with linear formations which were thought to be abnormal forms of endoplasmic reticulum. Well developed microvilli were found on the ciliated borders of ciliated cells, but no evidence was found of viral growth in this region

EFFECTS OF ANTICELLULAR SERUM ON PHAGOCYTOSIS AND THE UPTAKE OF TRITIATED THYMIDINE AND URIDINE BY HELA CELLS

Anticellular serum inhibited phagocytosis of colloidal gold and staphylococci by HeLa cells. This inhibition of phagocytosis was reversed by conditions which allowed the antibody to elute from the cell. Concentrations of antiserum that inhibited phagocytosis did not interfere with the transport of tritiated thymidine and uridine across the cell membrane, and their incorporation into cell nucleic acids was unaltered as evaluated by autoradiography. These results indicate that thymidine and uridine were taken into cells independently of phagocytosis. Morphologic changes induced in the cells by antibody suggest that the antibody agglutinates adjacent portions of the cell membrane. This agglutination of the cell membrane by antibody would be expected to interfere with the continuous evagination and invagination of the cell membrane associated with phagocytosis. The inhibition of virus infection by anticellular antibody may be a result of the effect of the antiserum upon phagocytosis

SULFONAMIDE CHEMOTHERAPY OF COMBINED INFECTION WITH INFLUENZA VIRUS AND BACTERIA

1. Sulfonamide chemotherapy controls the bacterial component of combined infection with influenza virus and pneumococci in rats. 2. Reinstillation of fluid (broth, physiological salt solution) into the respiratory passages of mice several days after sublethal viral infection converts the viral infection into a lethal one. 3. Sulfonamide chemotherapy controls the bacterial component of combined bacterial and viral infection of mice, produced by intrabronchial inoculation of mixtures of bacteria and sublethal or lethal doses of virus. 4. Bacterial pneumonia may be superimposed upon sublethal viral infection in mice by inhalation of fine droplets of bacterial suspension several days after inoculation of virus. Normal mice inhaling fine droplets of bacterial suspension fail to develop obvious disease. 5. Sulfonamide chemotheiapy controls bacterial pneumonia superimposed on sublethal viral infection by inhalation of fine droplets of bacterial culture. 6. The secondary bacterial penumonia does not convert the sublethal viral infection into a lethal one. 7. If another pandemic of influenza occurs, it is probable that sulfonamide chemotherapy will be valuable in the treatment of secondary bacterial pneumonia and will be effective in lowering the case fatality rate if the viral component of the infection is not severe enough by itself to cause death