SipA, SopA, SopB, SopD and SopE2 effector proteins of Salmonella enterica serovar Typhimurium are synthesized at late stages of infection in mice.

Salmonella pathogenicity island (SPI)-1 is essential for invasion of non-phagocytic cells, whereas SPI-2 is required for intracellular survival and proliferation in phagocytes. Some SPI-1 effectors, however, are induced upon invasion of both phagocytic and non-phagocytic cells, suggesting that they may also be required post-invasion. In the present work, the presence was analysed of SipA, SopA, SopB, SopD and SopE2 effector proteins of Salmonella enterica serovar Typhimurium in vitro and in vivo during murine salmonellosis. Tagged (3xFLAG) strains of S. enterica serovar Typhimurium were inoculated intraperitoneally or intragastrically to BALB/c mice and recovered from the spleen and mesenteric lymph nodes of moribund mice. Tagged proteins were detected by SDS-PAGE and immunoblotting with anti-FLAG antibodies. In vitro experiments showed that SPI-1 effector proteins SipA, SopA, SopB, SopD and SopE2 were secreted under SPI-1 conditions. Interestingly, it was found that S. enterica serovar Typhimurium continued to synthesize SipA, SopB, SopD and SopE2 in colonized organs for several days, regardless of the route of inoculation. Together, these results indicate that SPI-1 effector proteins may participate in the late stages of Salmonella infection in mice.

Immune system pathogenesis is prevented by the neutralization of the systemic trans-sialidase from Trypanosoma cruzi during severe infections.

During the acute phase of Trypanosoma cruzi infection, strong haematological and immune system alterations are observed. The parasite expresses trans-sialidase, a virulence factor responsible for the sialylation of its surface glycoconjugates. This enzyme is also shed to the bloodstream where it is associated with immune system alterations triggered during the infection. During experimental and human infections, the host elicits antibodies able to neutralize the enzyme activity that would be responsible for restricting systemic trans-sialidase to the early steps of the infection, when major immune alterations are induced. The actual relevance of these antibodies was tested by passive transference of monoclonal neutralizing antibodies in acute infection models displaying extreme sensitivity to the infection. Mice were inoculated with virulent parasite strains that induce high parasitaemia, early mortality and strong immune tissue abnormalities. The trans-sialidase-neutralizing antibodies were able to preserve B cell areas both in ganglia and spleen as well as the thymus architecture even in these extreme models. Although no differences between control and treated mice regarding animal survival were found, a major role for the humoral response in controlling the damage of the immune system induced by a systemically distributed virulence factor was defined in an infection with a eukaryotic pathogen.

Immunochemical and morphometric features of astrocyte reactivity vs. plaque location in Alzheimer's disease

The quantitative relationship between glial fibrillary acidic protein (GFAP) hyper-reactivity and -amyloid protein (AP) deposition was investigated by double immunoperoxidase labeling of hippocampal and entorhinal cortex sections from five Alzheimer´s disease (AD) cases and five age-matched controls. AP plaques, which were absent in controls, were found in all AD samples, without significant differences in number or perimeter according to their location among the regions studied. In contrast, the mean number of GFAP (+) cells was significantly greater in the hippocampus than in the entorhinal cortex from AD cases (49 vs.39). Although at lower values (30 vs. 20), predominance of astrocyte hyperplasia in hippocampus as compared with entorhinal cortex was also found in control samples. Concomitant astrocyte hypertrophy, as defined by surface density (Sv) values of GFAP-immunoreactive material exceeding those of control means, affected a similar proportion of cells in the hippocampus (73%) and the entorhinal cortex (74%) from AD cases. Since an increased number of GFAP (+) cells in the hippocampus was not accompanied by an increased number and/or perimeter of neighbouring plaques, such differential hyper-reactivity in samples from AD patients, as well as in those with normal aging, seems to depend partially on the regional location of the involved astrocyte.

Immunochemical and morphometric features of astrocyte reactivity vs. plaque location in Alzheimers disease

The quantitative relationship between glial fibrillary acidic protein (GFAP) hyper-reactivity and -amyloid protein (AP) deposition was investigated by double immunoperoxidase labeling of hippocampal and entorhinal cortex sections from five Alzheimer s disease (AD) cases and five age-matched controls. AP plaques, which were absent in controls, were found in all AD samples, without significant differences in number or perimeter according to their location among the regions studied. In contrast, the mean number of GFAP (+) cells was significantly greater in the hippocampus than in the entorhinal cortex from AD cases (49 vs.39). Although at lower values (30 vs. 20), predominance of astrocyte hyperplasia in hippocampus as compared with entorhinal cortex was also found in control samples. Concomitant astrocyte hypertrophy, as defined by surface density (Sv) values of GFAP-immunoreactive material exceeding those of control means, affected a similar proportion of cells in the hippocampus (73%) and the entorhinal cortex (74%) from AD cases. Since an increased number of GFAP (+) cells in the hippocampus was not accompanied by an increased number and/or perimeter of neighbouring plaques, such differential hyper-reactivity in samples from AD patients, as well as in those with normal aging, seems to depend partially on the regional location of the involved astrocyte. (AU)

Long-lasting astrocyte reaction to persistent Junin virus infection of rat cortical neurons.

Immunoperoxidase labeling was performed in histological sections from rat brain harvested during acute (10-30 days), clinically inapparent (90-270 days) and late (450-540 days) stages of Junin virus-induced neurological disease. In frontoparietal cortex, count of viral antigen (+) neurons peaked during the acute period (27.7+/-6.8), dropped within the intermediate (4.8+/-4.0 to 1.4+/-1.1) and increased (7.6+/-4.3) at the onset of the late neurological syndrome. In infected vs. control rats, the number of GFAP (+) astrocytes maximized during the acute stage (19+/-4 vs. 11+/-5), and from the end of the intermediate (27+/-5 vs. 21+/-5) up to the late (37+/-7 vs. 26+/-6) periods. In turn, surface density of GFAP (+) material in infected samples peaked at 0.196+/-0.066, while it failed to exceed 0.090+/-0.043 in controls. Both astrocyte hypertrophy relapsing into chronicity, as depicted by surface density, and astrocyte hyperplasia preceding the onset of the late neurological syndrome, support their pathogenic contribution to disease expression.

Akinetic mutism: a report of three cases.

OBJECTIVES: To report 3 new cases of akinetic mutism, a clinical syndrome defined by silent immobility with preserved visual alertness not accountable by lesion of the areas and/or effector pathways of speech and voluntary movements. MATERIAL AND METHODS: Anatomopathological studies were performed in Cases 1 and 2; clinical follow-up, EEG, angiography and CT scans in Case 3. RESULTS: Case 1: Bipallidal necrosis; Case 2: Left pallidal necrosis with right frontoparietal cortico-subcortical infarction; Case 3: Striato-capsular infarction on the left side, involving the caudate nucleus and the anterior arm of the internal capsule, together with obstructive hydrocephalus. CONCLUSION: The roles of both globus pallidus and prefrontostriatal circuits in the onset of voluntary movements are discussed.

Interstitial pneumonitis induced in guinea pigs by Triatoma infestans antigens.

Data concerning the experimental induction of hypersensitivity pneumonitis in guinea pigs with a Triatoma infestans antigen are presented. Glycoproteins obtained from the chitinous structures of T. infestans (79 kd + 11 kd) were aerosolized daily to guinea pigs during 7 weeks. The presence of specific antibodies (IgG and IgE) was detected by serological techniques; histopathological studies of the lungs showed interstitial infiltrates of macrophages and T-cells. Single non-necrotizing granulomas were seen at the seventh week of the experiment. The results from this animal model suggest that this hypersensitivity pneumonitis is a typical delayed-type reaction due to chronic contact with the heterologous glycoproteins of T. infestans.

Neural spread of Junin virus in intraperitoneally inoculated rats.

On the basis of an already demonstrated Junín virus (JV) neural route after peripheral footpad infection of newborn rats, here we attempted to determine the viral pathway following intraperitoneal inoculation. As from the 2nd week post-infection, neurological disease developed reaching 84% mortality at 30 days. Immunoperoxidase labeling of viral antigen, concomitantly with infectivity assays and histological examination, was carried out in serially harvested samples. Whenever infectivity was detected, whether by viral rescue from coculture or by conventional isolation, viral antigen staining was achieved. Infective JV was present at threshold levels in spleen and liver from days 2 to 10, and in blood from days 5 to 15. In neural tissues, viral antigen was initially disclosed at day 5 in thoracic rachideal ganglia and related spinal cord segments. From day 7 thereafter, the entire spinal cord was involved; at this stage, first evidence of viral infection was found in brain stem, with subsequent spread to other encephalon structures at day 10. According to harvested samples, no significant differences were found in labeled cell percentages at thoracic vs cervical or lumbar levels of spinal cord. In contrasts, greater involvement of cerebral cortex versus brain stem, hippocampus or cerebellum was demonstrated shortly before death. Although JV antigen was overwhelmingly predominant in neurons, no morphological changes were apparent in such cells. Since rachideal spinal ganglia and spinal cord infection invariably preceded viral spread to encephalon, concomitantly with viral clearance from lymphoreticular organs and blood, a neural pathway seems warranted.

Neural spread of Junin virus in intraperitoneally inoculated rats

Una vez establecida la ruta neural como la seguida por el virus Junín (VJ) a partir de su inoculación intradérmica en ratas lactantes, resultaba de interes determinar cuál era la vía adoptada luego de inoculado intraperitonealmente. Desde la 2da semana se evidenció una enfermedad neurológica que a los 30 días post-infección alcanzó un 84 por ciento de mortalidad. En curso de ese período, se efectuaron cosechas de tejidos extraneurales y neurales para la marcación por inmunoperoxidasa del antígenos viral y el examen histopatológico, asi como la titulación de infectividad que también se extendió a sangre. En todas las muestras de tejido en que se detectó virus infectivo, sea por cocultivo o por aislamiento convencional, se logró la marcación del antígeno viral. El VJ estuvo presente en valores mínimos en bazo e hígado desde el día 2 al 5, y en sangre del 5 al 15. En tejidos neurales, el antígeno viral fue inicialmente revelado al día 5, tanto en ganglios raquídeos torácicos como en los segmentos medulares relacionados. A partir del día 7, la positividad se extendió a la médula espinal en toda su extensión; a la vez, ya había evidencias de presencia viral en tronco cerebral, con disfusión al resto de estructuras encefálicas desde el día 10. Pese a la presencia masiva del antígeno viral en neuromas, dichas células no mostraban cambios morfológicos aparentes. Dado que la infección de ganglios raquídeos y de médula espinal invariablemente precedió al acesso viral a encéfalo, y ello ocurrió en forma concomitante a la desaparición del virus en órganos linfo-reticulares y en sangre, la vía neural parece ser la adoptada por el VJ desde cavidad peritoneal hasta sistema nervioso central

Neural spread of Junin virus in intraperitoneally inoculated rats.

On the basis of an already demonstrated Junín virus (JV) neural route after peripheral footpad infection of newborn rats, here we attempted to determine the viral pathway following intraperitoneal inoculation. As from the 2nd week post-infection, neurological disease developed reaching 84

mortality at 30 days. Immunoperoxidase labeling of viral antigen, concomitantly with infectivity assays and histological examination, was carried out in serially harvested samples. Whenever infectivity was detected, whether by viral rescue from coculture or by conventional isolation, viral antigen staining was achieved. Infective JV was present at threshold levels in spleen and liver from days 2 to 10, and in blood from days 5 to 15. In neural tissues, viral antigen was initially disclosed at day 5 in thoracic rachideal ganglia and related spinal cord segments. From day 7 thereafter, the entire spinal cord was involved; at this stage, first evidence of viral infection was found in brain stem, with subsequent spread to other encephalon structures at day 10. According to harvested samples, no significant differences were found in labeled cell percentages at thoracic vs cervical or lumbar levels of spinal cord. In contrasts, greater involvement of cerebral cortex versus brain stem, hippocampus or cerebellum was demonstrated shortly before death. Although JV antigen was overwhelmingly predominant in neurons, no morphological changes were apparent in such cells. Since rachideal spinal ganglia and spinal cord infection invariably preceded viral spread to encephalon, concomitantly with viral clearance from lymphoreticular organs and blood, a neural pathway seems warranted.

Neural spread of Junin virus in intraperitoneally inoculated rats

Una vez establecida la ruta neural como la seguida por el virus Junín (VJ) a partir de su inoculación intradérmica en ratas lactantes, resultaba de interes determinar cuál era la vía adoptada luego de inoculado intraperitonealmente. Desde la 2da semana se evidenció una enfermedad neurológica que a los 30 días post-infección alcanzó un 84 por ciento de mortalidad. En curso de ese período, se efectuaron cosechas de tejidos extraneurales y neurales para la marcación por inmunoperoxidasa del antígenos viral y el examen histopatológico, asi como la titulación de infectividad que también se extendió a sangre. En todas las muestras de tejido en que se detectó virus infectivo, sea por cocultivo o por aislamiento convencional, se logró la marcación del antígeno viral. El VJ estuvo presente en valores mínimos en bazo e hígado desde el día 2 al 5, y en sangre del 5 al 15. En tejidos neurales, el antígeno viral fue inicialmente revelado al día 5, tanto en ganglios raquídeos torácicos como en los segmentos medulares relacionados. A partir del día 7, la positividad se extendió a la médula espinal en toda su extensión; a la vez, ya había evidencias de presencia viral en tronco cerebral, con disfusión al resto de estructuras encefálicas desde el día 10. Pese a la presencia masiva del antígeno viral en neuromas, dichas células no mostraban cambios morfológicos aparentes. Dado que la infección de ganglios raquídeos y de médula espinal invariablemente precedió al acesso viral a encéfalo, y ello ocurrió en forma concomitante a la desaparición del virus en órganos linfo-reticulares y en sangre, la vía neural parece ser la adoptada por el VJ desde cavidad peritoneal hasta sistema nervioso central (AU)

Immunoperoxidase tracing of Junin virus neural route after footpad inoculation.

To determine the pathway adopted by peripherally inoculated Junin virus (JV) to reach the CNS, rat tissues were serially harvested to trace the sequence of viral progression from right hind footpad to brain. Immunoperoxidase (PAP) labeling of viral antigen, concomitantly with infectivity assays and histological examination of each selected sample, were carried out. As from the 2nd week post-infection (pi), neurological disease inducing 100% mortality at 1 month was evident. At day 5 pi, viral antigen was first detected at footpad level in epidermic and dermic cells, as well as in neighbouring myocytes; labeled macrophages infiltrating small nerve branches were also disclosed. As from 10-15 days pi, viral antigen became apparent along ipsilateral sciatic nerve structures and within lumbar spinal ganglion neurons, followed by a fast viral spread throughout CNS neurons that involved spinal cord and brain. Concurrent histopathology featured minimal inflammatory reaction together with generalized astrocytic activation. Hematogenous viral transport was negligible, since JV was isolated much earlier and in higher infectivity titers in neural tissues than in blood. It may be concluded that after viral replication in footpad, JV neural route was demonstrated by its PAP labeling from peripheral nerves to cerebral cortex.