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Aim: To assess the effect of tartrazine at ADI doses on ovarian integrity (the weight and histology of the ovary), reproductive fertility hormones (luteinizing hormones (LH), follicle stimulating hormone (FSH) and prolactin (PRL)) and oxidative stress markers (glutathione peroxidase (GPX) and superoxide dismutase (SOD)) over a period of 30 and 60 days in albino rats. Study Design: A total of 63 female rats weighing approximately 0.2kg were divided into two phases. In phase 1 (30 days treatment period), the rats were divided into 2 groups - designated tartrazine treated group (TTG1) consisting of 20 rats and control untreated group (CUG1) consisting of 15 rats. In phase 2 (60 days treatment period), the rats were again divided into 2 groups – tartrazine treated group (TTG2) consisting of 16 rats and control untreated group (CUG2) consisting of 12 rats. The acceptable daily intake (ADI) of 7.5mg/kg of the dye was administered orally while the control groups were given food and water only. Methodology: At the end of the study, the animals were anaesthetized and 5 mL of whole blood samples was collected by means of cardiac puncture into plain bottles, later spun at 4000 rpm for 5 minutes to obtain serum. The laboratory analysis of LH, FSH and PRL as well as GPX and SOD activity were based on Enzyme Linked Immunosorbent Assay (ELISA) Technique using rat-specific kits. Ovarian tissues collected were weighed using electronic balance, washed in normal saline, fixed in 10% formalin saline, embedded in paraffin wax, 5μm thick sections were obtained by rotary microtome, stained using Haematoxylin & Eosin and examined using digital Olympus microscopic. Results: Non-significant higher values in the absolute weight of the ovary (WOV), FSH, LH, and PRL while non-significant lower values in GPX and SOD were observed in the treated rats against control rats over a period of 30 and 60 days at P=.05. The histological examination over a period of 30 days did not indicate any alteration but hydropic dilation and structural alterations were seen after 60 days. Conclusion: The administration of ADI doses of tartrazine over a period of 60 days affected the integrity of the ovary mildly as observed in the histology but did not markly reflect on the biochemical markers in the plasma as well as the weight of the ovary.

Introduction The use of core outcome sets (COS) and common data elements (CDEs) minimises research wastage by increasing the cross-comparison and meta-analysis of study findings. Our study sought to identify the clinical neuroscience subspecialties that have developed COS and CDEs, the countries of origin of authors, and the process through which COS and CDEs were developed. Method A search between 2000-2020 of the top 40 Impact Factor neurosurgical and neurological journals was conducted. A scoping review was performed in accordance with the PRISMA-ScR Checklist. Results Our search returned 169 papers, of which 35 were eligible for inclusion. The USA published the majority of papers (20/35). The papers mostly related to neurosurgery (30/35), with the most common neurosurgical sub-specialty being traumatic brain injury (14/35). There is an increasing publication trend over time, with 12 papers published in 2019. Five papers were systematic reviews conducting with the intention of COS/CDE development. 27 papers reported CDE development and 2 papers reported COS development. The COS development papers utilised international consensus meetings and adhered to international development statements. Conclusions COS and CDEs are increasingly being developed within clinical neurosciences. There is a need for greater international collaboration with regards to COS and CDEs development.

Chronic liver disease (CLD) is associated with tissue-destructive fibrosis. Considering that common mechanisms drive fibrosis across etiologies, and that steatosis is an important cofactor for pathology, we performed RNA sequencing on liver biopsies of patients with different fibrosis stages, resulting from infection with hepatitis C virus (HCV) (with or without steatosis) or fatty liver disease. In combination with enhanced liver fibrosis score correlation analysis, we reveal a common set of genes associated with advanced fibrosis, as exemplified by those encoding the transcription factor ETS-homologous factor (EHF) and the extracellular matrix protein versican (VCAN). We identified 17 fibrosis-associated genes as candidate EHF targets and demonstrated that EHF regulates multiple fibrosis-associated genes, including VCAN, in hepatic stellate cells. Serum VCAN levels were also elevated in advanced fibrosis patients. Comparing biopsies from patients with HCV with or without steatosis, we identified a steatosis-enriched gene set associated with advanced fibrosis, validating follistatin-like protein 1 (FSTL1) as an exemplar of this profile. In patients with advanced fibrosis, serum FSTL1 levels were elevated in those with steatosis (versus those without). Liver Fstl1 mRNA levels were also elevated in murine CLD models. We thus reveal a common gene signature for CLD-associated liver fibrosis and potential biomarkers and/or targets for steatosis-associated liver fibrosis.

Aim: To investigate the influence of macrophages on hepatocyte phenotype and function. Methods: Macrophages were differentiated from THP-1 monocytes via phorbol myristate acetate stimulation and the effects of monocyte or macrophage-conditioned medium on HepG2 mRNA and protein expression determined. The in vivo relevance of these findings was confirmed using liver biopsies from 147 patients with hepatitis C virus (HCV) infection. Results: Conditioned media from macrophages, but not monocytes, induced a transient morphological change in hepatocytes associated with upregulation of vimentin (7.8 +/- 2.5-fold, P = 0.045) and transforming growth factor (TGF)-beta 1 (2.6 +/- 0.2-fold, P < 0.001) and downregulation of epithelial cadherin (1.7 +/- 0.02-fold, P = 0.017) mRNA expression. Microarray analysis revealed significant upregulation of lipocalin-2 (17-fold, P < 0.001) and pathways associated with inflammation, and substantial downregulation of pathways related to hepatocyte function. In patients with chronic HCV, real-time polymerase chain reaction and immunohistochemistry confirmed an increase in lipocalin-2 mRNA (F0 1.0 +/- 0.3, F1 2.2 +/- 0.2, F2 3.0 +/- 9.3, F3/4 4.0 +/- 0.8, P = 0.003) and protein expression (F1 1.0 +/- 0.5, F2 1.3 +/- 0.4, F3/4 3.6 +/- 0.4, P = 0.014) with increasing liver injury. High performance liquid chromatography-tandem mass spectrometry analysis identified elevated levels of matrix metalloproteinase (MMP)-9 in macrophage-conditioned medium, and a chemical inhibitor of MMP-9 attenuated the change in morphology and mRNA expression of TGF-beta 1 (2.9 +/- 0.2 vs 1.04 +/- 0.1, P < 0.001) in macrophage-conditioned media treated HepG2 cells. In patients with chronic HCV infection, hepatic mRNA expression of CD163 (F0 1.0 +/- 0.2, F1/2 2.8 +/- 0.3, F3/4 5.3 +/- 1.0, P = 0.001) and MMP-9 (F0 1.0 +/- 0.4, F1/2 2.8 +/- 0.3, F3/4 4.1 +/- 0.8, P = 0.011) was significantly associated with increasing stage of fibrosis. Conclusion: Secreted macrophage products alter the phenotype and function of hepatocytes, with increased expression of inflammatory mediators, suggesting that hepatocytes actively participate in liver injury Refereed/Peer-reviewed

The increased concentrations of neutralizing antibodies against influenza A virus in human serum which occur after influenza A do not differentiate between antigenically different strains of this virus or swine influenza virus but instead appear to possess equal reactivity against these agents. The decrease in antibody levels which occurs with time is also independent of the strain of virus used to measure it.

1. The addition of small amounts of cholesterol and of cephalin reduces markedly the protective action of antipneumococcus horse serum. 2. These lipids do not affect the protective action of antipneumococcus rabbit serum. 3. These findings may be explained (a)by the selective adsorption of lipid on the antigen-antibody complex, and (b) by certain lipid antagonisms. 4. The failure of large amounts of immune horse serum to protect mice against pneumococcus infection is explicable on the basis of selective participation of lipids dependent upon the species from which the antibody is derived. 5. The lipids modify the results of protection tests only through participation in the process of specific sensitization.

A technique has been devised for obtaining free or uncombined pneumonia virus of mice (PVM). Free PVM, liberated from infected mouse lungs by means of this technique, is infectious and causes hemagglutination directly. The results of quantitative studies carried out in the high speed angle centrifuge indicate that the free virus is relatively small, with dimensions of the order of 40 millimicrons. When it is in combination with lung tissue particles, PVM appears to be a relatively large virus with minimal dimensions of the order of 140 millimicrons. Non-infectious virus particles, released from combination with lung tissue particles by heating, are similar to the infectious free virus in size.

The infections produced in ferrets by human influenza virus and canine distemper virus were studied. Cross immunity and cross neutralization tests showed that these two viruses were not related antigenically. Ferrets infected with influenza virus alone rapidly produced considerable quantities of neutralizing antibodies, and after the 6th day virus was not demonstrable in their lungs. Ferrets infected with both influenza and distemper viruses simultaneously produced but small amounts of neutralizing antibody, and influenza virus persisted in undiminished concentration in their lungs throughout the course of the infection.

It has been demonstrated that the removal of lipoids from Type I antipneumococcus horse serum causes a loss of the visible phenomena of type specific agglutination and precipitation, and in the case of rabbit serum a marked reduction in these properties. Initial activity of the type specific antibody can be restored to extracted immune horse serum by the addition of lecithin, and to rabbit serum by the addition of cephalin. The significance of these observations in respect to the relation of phospholipins to the type specific reactions of antipneumococcus serum is discussed.

The results of studies on the immunological relationship between streptococcus MG and Streptococcus salivarius type I are described. Evidence is presented to show that Streptococcus salivarius type I, like streptococcus MG, possesses a capsular polysaccharide antigen. Similarities in the capsular polysaccharides of these two different species of non-hemolytic streptococci appear to be responsible for their immunological relationship.

Additional evidence is presented that PVM is capable of combining firmly with lung tissue particles or erythrocytes from certain susceptible species. Release of the virus from such combination can be effected by treatment with alkali as well as by heating. Free virus expressed from infected lungs without grinding the tissues is infectious and causes hemagglutination when tested directly. The concentration of virus can be estimated more accurately by means of the hemagglutination technique than from the results of infectivity tests in mice. Present evidence indicates that PVM may occur in 4 different states and that in each state it manifests distinctive properties.

1. The cause for the phenomenon of hemagglutination with heated PVM suspensions has been sought. 2. Evidence in wide variety indicates that the component responsible for hemagglutination is the virus particle itself. 3. The virus is capable of combining with a substance present in lung tissue of certain mammalian host species susceptible to infection by PVM. The occurrence of such combination accounts for a number of unusual properties manifested by this pneumotropic virus.

1. Complement is not fixed by immune aggregates resulting from the interaction of pneumococcus capsular polysaccharide and type-specific immune horse serum, although under proper conditions the substitution of immune rabbit serum gives positive results. 2. The negative results with immune horse serum are due to some poorly understood property of the specific antibodies rather than to some heterologous inhibitor present in the serum. 3. It has been shown that with immune rabbit serum-polysaccharide combinations, complement fixation is an adsorptive phenomenon conditioned upon the surface exposure of the immune aggregates. 4. A close parallelism to the selective adsorption of phosphatides by these immune aggregates has been pointed out. 5. In those instances in which complement is fixed this phenomenon must be regarded as tertiary and conditioned by (a) union of antigen and antibody, and (b) particulation. 6. The general significance of complement fixation as applied to bacterial polysaccharides has been discussed.

By means of the improved electrophoretic technique it has been possible to study the association products which are formed when mixed and dissociated hemocyanins from two different species are reassociated. Both the dissociation and the reassociation of the hemocyanins have been produced simply by altering the pH of the solutions. Scale method electrophoretic diagrams have been used throughout this investigation. This method has adequately demonstrated its advantages and has permitted exact calculations of the mobility, concentration, and homogeneity of components which were either present in too small an amount or were too nearly similar electrochemically to have been defined by other methods. Evidence has been presented which indicates that a number of mixed hemocyanins have been produced. These mixed hemocyanin molecules contain fractions of the dissociated hemocyanins from two different species.

1. Specific precipitates resulting from the interaction of the homologous capsular polysaccharide and Type I antipneumococcus horse and rabbit sera have been analyzed by gasometric micro methods for total nitrogen, lipid nitrogen, and lipid carbon. 2. Lipid may, under certain conditions, form as much as 51 per cent or as little as 4 per cent by weight of specific precipitates. 3. The total lipid content of specific precipitates, within the range studied, is entirely independent of the protein content. 4. Lipid nitrogen forms a very small but detectable portion of the total nitrogen of precipitates. 5. The absolute lipid content of precipitates is a function of the concentration of lipid in the reacting mixture prior to precipitation, and seems to be governed by the laws of adsorption phenomena.

This study on pneumonia virus of mice (PVM) was carried out in order to obtain as accurate data as possible on the degree of variation which may be expected in titrations of the virus or of antibodies against it in vivo. It is believed that the knowledge gained will facilitate further investigations on this latent pneumotropic virus and make possible a more exact assessment of the significance of experimental results obtained with the agent. The reproducibility of 50 per cent maximum score titration end points with PVM in mice is such that the chances are 19 out of 20 that a difference of 1.084 log units (i.e. a twelvefold difference) in the end points obtained in two separate titrations is significant. The reproducibility of 50 per cent maximum score serum dilution end points in neutralization tests with PVM in mice is such that the chances are 19 out of 20 that a difference of 0.626 log units (i.e. a fourfold difference) in the end points obtained with two sera against similar amounts of virus is significant. It was found that there is a linear exponential relationship between the serum dilution end point and the quantity of PVM used in a neutralization test. This relationship appears to be identical with immune serum obtained from different animal species, and appears also to be identical to the linear relationship described previously in similar studies with influenza A virus.

Influenza complement fixation tests designed for use with ferret serum are described. Complement-fixing antigens derived from influenza ferret lungs were unsatisfactory due to their low content of soluble antigen; those prepared from mouse lungs or developing chick embryo membranes proved to be better antigenically and were reliable when the various reagents in the test were properly adjusted to eliminate non-specific fixation of complement. The results of cross complement fixation tests indicated that the soluble antigens of the PR8 and W.S. strains of influenza A virus were closely similar, if not identical. They indicated also that the soluble antigen of swine virus possessed components present in the antigens of the human strains of virus.

1. Type I antipneumococcus horse serum, in amounts exceeding a characteristic optimum, fails to protect mice against infection with the homologous type pneumococci. This failure is due to a marked inhibition of the phagocytic mechanism in the earlier stages of the infectious process. On the other hand, antipneumococcus rabbit serum in similar quantities does not inhibit phagocytosis, nor does it block the protection. 2. The experimental evidence suggests that the prozoning action of immune horse serum is due primarily to some characteristic property of the specific antibody and secondarily to an heterologous component of the serum, ineffective in itself but acting through the mediation of the antigen-antibody combination. This secondary factor may be a lipid.

A linear relationship exists between the quantity of human serum used and the quantity of influenza A virus neutralized. By means of this relationship it is possible to determine the maximum quantity of virus which a given human serum can neutralize. This quantity, the neutralizing capacity, is a fixed value and, unlike the serum dilution end point, is independent of the amount of virus used in the neutralization test.

Evidence is presented which indicates that certain polysaccharide preparations derived from various bacterial species, as well as similar materials not of bacterial origin, are capable of lessening the severity of infection with pneumonia virus of mice (PVM) and inhibiting multiplication of the virus in mouse lungs infected with this agent. It seems probable that modification with respect to the virus is mediated by a substance which may be polysaccharide in nature.

1. The addition of small amounts of cholesterol and of cephalin reduces markedly the protective action of antipneumococcus horse serum. 2. These lipids do not affect the protective action of antipneumococcus rabbit serum. 3. These findings may be explained (a)by the selective adsorption of lipid on the antigen-antibody complex, and (b) by certain lipid antagonisms. 4. The failure of large amounts of immune horse serum to protect mice against pneumococcus infection is explicable on the basis of selective participation of lipids dependent upon the species from which the antibody is derived. 5. The lipids modify the results of protection tests only through participation in the process of specific sensitization.

Influenza A virus, PR8 strain, increases in amount in the infected mouse lung at a relatively constant rate. When more than 25 M.S.50 doses of virus is inoculated, the rate of multiplication appears to be independent of the amount of virus introduced; has a value of 1,100-fold increase per day. The rate of increase in the pulmonary lesions induced by infection of the mouse lung with PR8 also appears to be relatively constant and independent of the amount of virus inoculated; has a value of 8.5-fold increase per day. The essential variables in the PR8-mouse lung system appear to be equated satisfactorily by functions which were derived previously (4) during a similar quantitative investigation on pneumonia virus of mice (PVM). Evidence in support of the hypothesis that the processes of multiplication of PR8 and PVM are different in the mouse lung is presented.

The results of neutralization tests with PVM and serum obtained from numerous animal species indicate that antibodies agaiust this virus were present in the blood of all mammalian species tested, as not in that of fowls, and that their incidence in various species was widely different. They indicate, also, that in certain species, particularly the cotton rat, there were marked seasonal variations in the incidence of such antibodies; in the late winter and spring the incidence was much higher than during the summer and fall seasons. Cotton rats and hamsters which did not possess neutralizing antibodies against PVM were susceptible to manifest pulmonary infection with this virus, irrespective of the effects of previous experiments upon them, whereas those which possessed such antibodies were immune. It is suggested that circulating antibodies against PVM were present as a result of preceding infection with a latent virus; either PVM or an agent closely related to it in antigenic composition. Appropriate non-specific stimuli, e.g. the intranasal injection of suspensions of normal chick embryos, induced the development of neutralizing antibodies against PVM with significantly greater frequency in each of three species than occurred in control animals. Materials derived from patients with primary atypical pneumonia yielded results almost identical to those obtained with normal chick embryo suspensions. It is suggested that such materials, like the other non-specific stimuli employed, were effective in evoking a specific antibody response, because they unbalanced an equilibrium which previously existed between animal host and latent pneumotropic virus.

A linear relationship exists between the logarithm of the quantity of epidemic influenza virus neutralized and the logarithm of the quantity of antiserum which is capable of achieving this result. This relationship is the same for the serum of a ferret convalescent from experimental influenza as for the serum of a rabbit immunized with the virus. By means of the linear relationship between virus and antiserum it is possible to determine a fixed, rather than a relative, value for the neutralizing capacity of a serum.

W ITHIN the past year a number of significant advances have been made as a result of laboratory investigations of epidemics of influenza. A second etiological agent has been discovered. Indirect evidence has been obtained that at least a third causal agent exists. Two new diagnostic technics have been described. In the case of influenza A it has been found that artificially increased antibody levels* are associated with decreased susceptibility to the disease. The possibility that the etiology of influenza was varied has been recognized for some time. Within two years of the discovery of the first influenza virus by Smith, Andrewes, and Laidlaw 1 these investigators recognized that clinical influenza was probably not a single etiological entity.2 Two years later Francis 3 showed that an epidemic of influenza could occur in the absence of demonstrable infection by the virus of the British workers. Additional epidemics of influenza which occurred in 1940 in England4 and this country 5' 6 were also found not to have been associated with what is now termed influenza A virus.7 As is well known, numerous workersin various parts of the world showed during the period 1935-1940 that in many epidemics influenza A virus had been causally related to the disease. During the past year. it was

Antigenic variants of influenza A virus strains emerge on serial passage in ovo in the presence of immune serum against different but related strains. An old laboratory strain (PR8) which had been through hundreds of animal passages was as readily modified by this procedure as recently recovered strains. Such variants apparently can be obtained at will and show antigenic patterns which are reproducible and appear to be predictable in terms of the immune serum used for their selection. Variant strains retain their new antigenic patterns on serial passage in ovo in the absence of immune serum. Limited serial passage in ovo of strains in the absence of immune serum did not result in the emergence of antigenic variants. Similarly, serial passages of strains in ovo in the presence of immune serum against widely different strains, which failed to show significant cross-neutralization, did not lead to the appearance of antigenic variants.

Evidence has been obtained which indicates that the lung tissues of mammalian species susceptible to infection with PVM contain a specific component which combines with the virus. The concentration of this tissue component appears to be directly proportional to the suceptibility of the species; in its absence infection with PVM cannot be established. The available evidence suggests that the presence of the virus-combining component in lung tissue may play a decisive ro1e in the initiation of infection with this pneumotropic virus.

Reciprocal interference between influenza A, influenza B, and swine influenza viruses has been demonstrated in the chick embryo. Certain temporal and quantitative factors which influence the production of interference in this host-virus system have been studied. The implications of these observations in relation to the mechanism by which interference is produced are discussed.

1. A virus capable of producing fatal pneumonia in mice has been isolated repeatedly from the lungs of certain apparently healthy mice. Not all mice carry the virus. It was obtained only from mice supplied by three breeders although mice from eight different sources were studied. 2. The virus was avirulent as it occurred in normal mouse lungs and became virulent only after serial mouse lung passage. It was strictly pneumotropic for mice and produced pneumonia when given intranasally but showed no evidence of infection when given by other routes. The virus was non-infectious for ferrets and did not become pathogenic for this species after numerous serial passages. It was also non-pathogenic for rabbits, guinea pigs, rhesus monkeys, voles, deer mice, skunks, wood-chucks, opossums, and Syrian hamsters. 3. All strains of the virus which have been tested have been immunologically identical, as indicated both by cross immunity and cross neutralization tests in mice. 4. The virus was antigenic both in mice and in rabbits and was readily differentiated from viruses of human influenza and of swine influenza by means of either cross immunity or cross neutralization tests. 5. The virus was also neutralized by about 30 per cent of normal human sera tested. 6. The virus was extremely labile, and suspensions prepared in saline or broth became inactivated within a few hours at room temperature. The addition of normal horse serum to the virus suspensions, however, exerted a definite stabilizing effect. 7. Ultrafiltration results indicated that the virus particles have a diameter of about 100 to 150 millimicrons. 8. Evidence is presented which indicates that this virus is different from other viruses which various investigators have found in normal mouse lungs.

The generally held view has been that in any immune serum only a single antibody would be induced by and react with a single antigen. Were this true the various manifestations of antibody activity should show a quantitative parallelism. It has already been shown (1), however, that with antipneumococcus horse serum the mouse protective potency does not parallel the maximum amount of specifically precipitable protein except within certain well defined groups of antisera. The simplest explanation of this situation is that different horses form antibodies differing in specific protective capacity, but from our studies it seems probable that in any immune serum there may occur a mixture of antibodies which, while directed against the same antigen, possess different protective capacities, different avidities, etc. It would now appear that this latter hypothesis is the more tenable since the experiments here reported indicate the existence of antibodies of various protective potencies in horse antisera. It would not be unreasonable to hold that the antibodies of a single serum represent a series of substances with varying properties. On the basis of the present immunological fractionation experiments, the following deductions seem permissible. 1. Antipneumococcus horse sera must contain at least three, possibly many, antibody substances which react with the capsular polysaccharide. These are: (a) A substance which precipitates upon the addition of a relatively small amount of polysaccharide. This antibody possesses a low protective potency. (b) A substance which is precipitated with intermediate amounts of polysaccharide and which possesses an extremely high protective value. (c) A third substance which is precipitated only with the addition of relatively large amounts of polysaccharide. The protective value of this antibody is very low It may represent a degraded form. 2. With antipneumococcus rabbit serum the situation is somewhat simpler. This is in accord with the fact that with Type I antipneumococcus sera from this species there is a direct proportionality between the amount of specifically precipitable protein and the protective potency of the serum (1). The results with antipneumococcus rabbit serum indicate the existence of at least two antibody substances: (a) An antibody with high protective value which makes up the greater proportion of the total content. (b) A second substance which is precipitated only upon the addition of relatively large amounts of capsular polysaccharide. The existence of this second antibody is not clearly demonstrated by the present findings but the lower protective ratios obtained as greater amounts of antibody are removed probably indicate its existence. This may also represent degraded material. The observations on the antibodies of both horse and rabbit antisera will be supported by experiments with immunochemical fractionation which will be reported in a subsequent paper.

1. The hemagglutinating capacity, enzymic activity, and infectivity of several influenza viruses were destroyed by repeated freezing and thawing of dialyzed allantoic fluids containing them. 2. Influenza virus degraded by freezing and thawing, by treatment with 5 M urea, or by heating at 65°C. still combined with homologous antibody and was demonstrable by blocking of the hemagglutination-inhibition and virus neutralization reactions. 3. After 50 cycles of freezing and thawing, much of the blocking antigen activity was not sedimented by centrifugation at 120,000 g for 2 hours, and electron microscopy showed complete disruption of the virus particles. So called soluble blocking antigen was obtained from four strains of influenza A, the Lee strain of influenza B, mumps, and Newcastle disease viruses. 4. Soluble blocking antigens from influenza A viruses were highly strain-specific; gave little or no reaction in complement-fixation tests; stimulated but little antibody production in rabbits and did not induce immunity in mice; caused reactivation of infective virus in neutral mixtures of homologous virus and immune serum. 5. Repeatedly frozen and thawed influenza virus preparations did not interfere with the propagation of infective virus in the allantoic sac. The blocking antigen activity they contained was precipitated by half saturated ammonium sulfate, destroyed by trypsin, chymotrypsin, or heating at 56°C. for 30 minutes, but was unaffected by desoxyribonuclease or ribonuclease. 6. These findings are in accord with the view that soluble blocking antigen obtained from influenza virus particles on disruption by repeated freezing and thawing is protein in nature and represents the essential antigenic material of the intact virus.

Serial passage of mumps virus in the presence of inhibitory quantities of the capsular polysaccharide of Friediänder bacillus type B results in the appearance of a variant strain of the virus. Multiplication of the variant virus is not inhibited by the polysaccharide. A similar resistant variant is obtained with polysaccharide in a single cycle of multiplication when very large inocula of mumps virus are employed. The resistant variant is indistinguishable from the parent strain as to infectivity, reactivity with erythrocytes, and immunological properties, but appears to have a somewhat slower rate of multiplication. Serial passage of the resistant variant in the absence of polysaccharide results in the reappearance of a sensitive strain. It is suggested that mumps virus populations are inhomogeneous; that naturally occurring variants are present in such populations and possess distinctive properties; that the use of a chemical inhibitor of mumps virus multiplication makes possible the selection of a variant possessing a predictable property. The findings are discussed in relation to the mechanism of inhibition of mumps virus multiplication by polysaccharide.

Evidence is presented which indicates that PVM is affected adversely in concentrated lung tissue suspensions or in the presence of glutathione. Because iodoacetamide inhibits or eliminates these effects in a similar manner, it is concluded that sulfhydryl groups are essential to their development.

The type specific immunological properties of certain non-hemolytic streptococci, including Str. salivarius type I and type II, present in the respiratory tract of human beings appear to be dependent upon the presence of capsular polysaccharides. The levans formed from sucrose by Str. salivarius (encapsulated S cells or non-encapsulated R variants), or by cell-free enzymes derived from these microorganisms, are indistinguishable immunologically and show no evidence of type specificity. Such levans appear to be immunologically distinct from and unrelated to the capsular polysaccharides of the microorganisms which produce them.

Combination between PVM and erythrocytes as well as between the influenza viruses and erythrocytes is inhibited at low electrolyte concentrations. Combination between PVM and lung particles as well as between the virus and erythrocytes can be dissociated in solutions of low electrolyte concentration. The rate of elution of influenza virus is decreased under similar conditions. PVM can combine with and be dissociated from erythrocytes repeatedly without affecting the combining capacity of the ceils and does not possess an enzyme-like activity similar to that of the influenza viruses. Because dissociation depends on electrolyte concentration and pH, it appears that the PVM-cell component complex may be in the nature of a weak salt.

1. A virus capable of producing pulmonary consolidation in the wild mongoose (Herpestes griseus) has been isolated from throat washings obtained from four patients with a clinical syndrome termed acute pneumonitis. 2. The virus was not pathogenic for ferrets, mice, guinea pigs, rabbits, monkeys, voles, hamsters, deer mice, skunks, opossums, or woodchucks. 3. The virus was filterable through Berkefeld V and N candles, was not inactivated by glycerin or by freezing and drying in vacuum, and was propagated for at least 30 serial passages on the chorio-allantoic membrane of the developing chick embryo. 4. Normal mongooses placed in contact with infected mongooses developed pulmonary consolidation. 5. The virus was neutralized by the serum of mongooses convalescent from the infection but was not neutralized by normal mongoose serum. 6. Serum of human beings convalescent from acute pneumonitis also neutralized the virus, but serum obtained from the same individuals during the acute phase of the disease failed to do so. 7. The evidence so far obtained strongly suggests that this virus is the cause of acute pneumonitis in human beings. It differs from other viruses known to cause infections of the respiratory tract in man.

Polysaccharides which cause inhibition of the multiplication of mumps virus in the allantoic sac may or may not cause inhibition of hemagglutination by the virus. Moreover, such substances may or may not prevent adsorption of the virus by erythrocytes. The available evidence indicates that polysaccharides active as inhibitors do not block adsorption of mumps virus by cells of the living allantoic membrane. With influenza A, influenza B, and Newcastle disease viruses, as well as with PVM, there also appears to be a lack of correlation between the in vitro and in vivo inhibiting activity of polysaccharides.

A quantitative study of the antigenicity of various vaccines containing influenza A virus has been made in human beings. A complex vaccine prepared from chick embryos inoculated with both influenza A virus and the X strain of canine distemper virus was found to be more effective than other vaccines in stimulating the production of neutralizing antibodies against the former virus. The increased antibody levels which resulted from the administration of this vaccine remained almost unaltered for at least 5 months.