[Human immunodeficiency virus infection associated with tuberculosis]. / Asociación de la infección por el virus de la inmunodeficiencia humana (HIV) y tuberculosis.

In order to detect an association between HIV infection and tuberculosis (TB), 130 TB inpatients were studied one of whom presented a pulmonary disease due to Mycobacterium avium intracellulare. All had advanced TB, 95.4%, with pulmonary localization. Serum anti-HIV antibodies were detected by ELISA and their presence confirmed by immunoblotting in 4 (3.1%) individuals, three males and one female, with different degrees of pulmonary TB. Of the males, 1 was bisexual, 2 were promiscuous, and the female was the sexual partner of a non symptomatic HIV-infected man. No immunological disturbances or other AIDS related alterations were observed. There was one case of miliary TB, but neither atypical X-ray abnormalities nor extrapulmonary involvement were found. Tuberculin reaction was positive in three of the four HIV infected patients. Clinical, radiological and bacteriological evolution were favorable. Adverse drug reaction occurred in two cases, one of them presenting serious toxidermia caused by isoniazid. Of the 130 individuals, 12 presented risk factors for HIV infection so that the prevalence of anti-HIV antibodies presented here, 4 cases out of 12, is consistent with data from previous reports for high risk populations.

Asociación de la infección por el virus de la inmunodeficiencia humana (HIV) y tuberculosis. / [Human immunodeficiency virus infection associated with tuberculosis]

In order to detect an association between HIV infection and tuberculosis (TB), 130 TB inpatients were studied one of whom presented a pulmonary disease due to Mycobacterium avium intracellulare. All had advanced TB, 95.4

, with pulmonary localization. Serum anti-HIV antibodies were detected by ELISA and their presence confirmed by immunoblotting in 4 (3.1

) individuals, three males and one female, with different degrees of pulmonary TB. Of the males, 1 was bisexual, 2 were promiscuous, and the female was the sexual partner of a non symptomatic HIV-infected man. No immunological disturbances or other AIDS related alterations were observed. There was one case of miliary TB, but neither atypical X-ray abnormalities nor extrapulmonary involvement were found. Tuberculin reaction was positive in three of the four HIV infected patients. Clinical, radiological and bacteriological evolution were favorable. Adverse drug reaction occurred in two cases, one of them presenting serious toxidermia caused by isoniazid. Of the 130 individuals, 12 presented risk factors for HIV infection so that the prevalence of anti-HIV antibodies presented here, 4 cases out of 12, is consistent with data from previous reports for high risk populations.

Mouse splenocyte transfer effect depends on donor's Junin virus infection stage.

Splenocytes from Junin-virus-persistently-infected euthymic mice taken at 45 days postinfection seemed unable to induce overt signs of disease, to cause death, or to modify brain viral levels when transferred to athymic Junin-virus-infected mice. Findings differed sharply when the same recipients were transferred with splenocytes taken at 6 or 30 days postinfection from immunocompetent mice infected in adult life, since mortality reached 80 or 50%, respectively, and brain viral titers were significantly lowered. Furthermore, splenocytes taken at 6 days postinfection from whole adult mice proved harmless to persistently infected euthymic mice. These findings strongly suggest the existence of an immune system alteration in the immunocompetent mouse, attributable to Junin virus persistence. This premise is based on the fact that splenocytes from persistently infected mice were unable to recognize viral antigen expressed on recipient-infected cells. The absence or impairment of a specific cytotoxic T cell population is hereby postulated.

Junín virus persistence in mice.

Newborn mice surviving intracerebral infection with Junín virus (JV) strain XJ showed viral persistence in brain up to 140 days post-infection (p.i.). Mild meningoencephalitis or encephalitis, but not the neutralizing antibody titres (NtAb) correlated with virus presence.

Modification of Junin virus neurotropism in mice by selective brain or spinal cord passaging.

The percentage of suckling mice that developed paralysis after intracerebral Junin virus (XJ-JV pathogenic strain) inoculation (13.8%) consistently increased after 5 serial passages of virus-infected brain or spinal cord obtained from paralytic animals, reaching 37.9 and 45.7%, respectively. As expected, all paralytic mice exhibited an identical spinal cord histologic picture, with widespread JV antigen in spinal cord astrocytes and neurons, particularly the large motor neurons of the anterior horn. These findings strongly support the existence of a motor neurotropic viral particle subpopulation in parental XJ-JV stock.

Early protection to Junín virus of guinea pig with an attenuated Junín virus strain.

Inoculation of guinea pigs with attenuated XJO Junín virus (JV) strain confers protection against challenge with pathogenic XJ-JV strain starting as early as 3 days post infection (p.i.). The protection increased continuously up to 100% by 30 days p.i. Neither stimulation of non-specific cell mediated mechanisms by previous BCG sensitization nor circulating interferon (IFN) seemed essential for such protection. The early detection of the virus in guinea pig organs considered the site of primary JV multiplication suggests that early resistance phenomenon was attributed mainly to direct viral interference.

MRC-5 cells, a model for Junín virus persistent infection.

Persistent infection of MRC-5 cells was established following inoculation with attenuated Junín virus (JV). In the acute phase of the infection both the pathogenic XJ and the attenuated XJ0 and XJC13 strains showed severe c.p.e. and free viral titres reached 10(5) p.f.u./ml. Recovery and establishment of persistently infected MRC-5 sublines (MRC-5PI) proved a very common event and seemed to be independent of viral strain, m.o.i. employed or virus passage history. These MRC-5PI sublines released virus throughout their life span and infectious centre assays performed at different passage levels with two sublines showed that 5 to 9% of the cells were producing virus. Heterotypic but not heterologous resistance to superinfection developed, as observed in persistent JV-heteroploid cell systems. Analysis of released JV showed that attenuation had not been markedly altered, but alteration in plaque morphology under methyl cellulose, appearance of temperature-sensitive mutants and alterations in mouse pathology imply that some properties of JV have been altered. Results presented here stress once again the ability of JV to establish persistent infections. The source and diploid characteristics of MRC-5 cells make them a satisfactory model for JV persistence studies.

Pathogenesis of attenuated Junin virus in the guinea pig model.

The purpose of this work was to elucidate the pathogenesis of attenuated Junin virus (JV) strains in the guinea pig model. Three groups of guinea pigs were infected by the IM route with 10(3) PFU of the XJC13 and XJO-attenuated strains or with the XJ pathogenic strain of JV, respectively. Viremia was studied at 3, 5, 7, 9, 12, and 14 days postinfection (pi) (a) in serum samples of all animals and in washed cells from XJC13-infected guinea pigs by conventional techniques and (b) in whole blood samples from XJC13 and XJO animals by coculture with Vero cells. Virus spread was studied at 14 days pi in brain, spleen, lymph nodes, and bone marrow by parallel suckling mouse inoculation or organ homogenates and coculture of cell suspensions with Vero cells. By coculture techniques of whole blood, an otherwise undetectable viremia was demonstrated for both attenuated strains throughout the observation period. In contrast, XJ viremia was easily detected by direct techniques, as has already been shown. Attenuated virus was also shown to reach brain and bone marrow when coculture methods were employed. But titers were always markedly lower than those of the pathogenic strain. The sustained viremia demonstrated in guinea pigs infected with either attenuated strain explains the mode of viral dissemination and accounts for viral rescue and antigen detection from some organs. These results suggest that attenuated strains do not differ greatly in their invasive capacity in guinea pigs, but later on viral replication is impaired. Therefore, these findings reveal potential risks and should be noted when developing human vaccines.

Infection of pregnant guinea pigs with attenuated Junin virus strains.

The effect of the attenuated XJC13 and XJ0 strains of Junin virus (JV) was studied in guinea pigs infected before and during pregnancy. The 58% mortality rate in animals infected during gestation and the 16.7% mortality rate in chronically infected animals were attributed to a viral effect. An abortion rate of 33% occurred in animals infected before the 7th week of gestation. Regardless of the time of infection, JV was isolated from central nervous system tissue, placentas, and fetuses of animals killed just before parturition, even when circulating neutralizing antibodies were present. Results confirmed that transplacental infection is a regular event and showed that guinea pigs are more susceptible to attenuated JV strains during pregnancy, most probably due to immunosuppression, hormonal changes, or both.

Congenital guinea pig infection with attenuated Junin virus strains.

Guinea pigs born from mothers infected before or during pregnancy with 10(3) PFU of the attenuated XJC13 or XJ0 strains of Junin virus (JV) by the intramuscular route showed 31.5% mortality that was not attributable to the mothers' clinical condition or to lack of care. There was a slight drop in mortality rate when the mothers were infected at the beginning or end of their gestation period. JV isolation from the 9 offspring killed from 1 to 125 days of age proved that virus transmitted transplacentally or soon after birth was able to persist, although titers were not higher than 10(2.7) PFU/g of tissue in various organs, including brain. Cell-associated viremia could thus account for viral spread after birth. Since an active humoral response was detected in the same animals, although Nt antibody titers were below 1:16, a state of tolerance did not exist in these congenitally infected animals. The carrier state appeared to modify guinea pig susceptibility to JV; after challenge with the pathogenic XJ strain of JV, 2 animals survived and developed normal humoral responses, while half of the remaining animals did not show typical signs of Argentine hemorrhagic fever. Although JV persistence appeared to cause no deleterious effects in surviving guinea pigs, its long-term risk remains to be determined.

[Association of the infection of the thymus and bone marrow with the establishment of persistent infection with Junin virus in 2 genera of rodents]. / Asociación de la infección del timo y médula ósea con el establecimiento de la infección persistente con virus Junín en dos géneros de roedores.

Junin virus infection of immune system organs was correlated with persistence establishment in the mouse and rat. Rockland mice under 24 or at 72 and 120 h of age received 10(4) pfu of Junin virus XJ strain by ic route. Separately, two groups of mice under 24 h old were infected with the same dose of XJ or XJCl3 strain by the same route respectively. Results showed that higher thymus virus titer correlated with greater survival. In turn, the former also seemed to correlate with decreasing age at inoculation time, although there was considerable strain dependence. In order to correlate replication levels in thymus with clinical progress in mice, animals under 24 h of age were inoculated with XJ. At 14 days pi apparently healthy mice from this batch were separated from those presenting severe neurologic sings. In the asymptomatic mice, thymus titers ranged from 1.7 to 3.2 log, while no virus was found in thymus harvested from obviously ill animals. However brain virus titers in the two groups proved similar. To confirm these findings, 72 h old Wistar rats were inoculated in with 10(4) pfu of either Junin virus strain: with XJ strain (90% survival) virus could be readily isolated from thymus and bone marrow at day 7 pi, whereas with XJCl3 (5% survival) no virus could be rescued from any organ tested. Therefore, our results strongly suggest a close correlation between productive thymic infection and Junin virus persistence establishment in these rodents, depending on immune response regulation rather than on viral variation.

Asociación de la infección del timo y médula ósea con el establecimiento de la infección persistente con virus Junín en dos géneros de roedores. / [Association of the infection of the thymus and bone marrow with the establishment of persistent infection with Junin virus in 2 genera of rodents]

Junin virus infection of immune system organs was correlated with persistence establishment in the mouse and rat. Rockland mice under 24 or at 72 and 120 h of age received 10(4) pfu of Junin virus XJ strain by ic route. Separately, two groups of mice under 24 h old were infected with the same dose of XJ or XJCl3 strain by the same route respectively. Results showed that higher thymus virus titer correlated with greater survival. In turn, the former also seemed to correlate with decreasing age at inoculation time, although there was considerable strain dependence. In order to correlate replication levels in thymus with clinical progress in mice, animals under 24 h of age were inoculated with XJ. At 14 days pi apparently healthy mice from this batch were separated from those presenting severe neurologic sings. In the asymptomatic mice, thymus titers ranged from 1.7 to 3.2 log, while no virus was found in thymus harvested from obviously ill animals. However brain virus titers in the two groups proved similar. To confirm these findings, 72 h old Wistar rats were inoculated in with 10(4) pfu of either Junin virus strain: with XJ strain (90

survival) virus could be readily isolated from thymus and bone marrow at day 7 pi, whereas with XJCl3 (5

survival) no virus could be rescued from any organ tested. Therefore, our results strongly suggest a close correlation between productive thymic infection and Junin virus persistence establishment in these rodents, depending on immune response regulation rather than on viral variation.

Modification of Junin virus neutropism in the guinea pig model.

Virulent and attenuated Junin virus (JV) strains have been employed to study the influence of virus passage history on the neurotropism for guinea pigs. Five i.p. successive passages (P1-P5) of the pathogenic JV-XJ strain and of the attenuated XJO variant were performed in guinea pig spleen. Viral titrations of organ suspensions were made through P1-P5 passages. The XJ strain produced a widespread infection in P1 guinea pigs with viral dissemination to all organs except brain, in P5 animals the brain has been involved as well. XJO-infected P1 guinea pigs showed lower viral titres than XJ-infected P1 animals, and again, the virus reached the CNS in P5 only. The passaging by i.p. route was shown to enhance CNS invasivity of the XJ strain as well as to maintain the XJO neurotropism for guinea pigs. Neurotropism of both strains seemed somewhat affected by the passage history of the virus and the inoculation route appeared critical for its expression. In addition, the neurotropic potential of the attenuated strains has apparently remained unaltered.

Transplacental infection in guinea pigs inoculated with an attenuated strain of Junin virus.

Transplacental infection by the attenuated XJC13 strain of Junin virus (JV) in the guinea pig model was evaluated. 5 pregnant guinea pigs were infected intramuscularly at 45 +/- 3 days of pregnancy. 4 animals were killed at 14 days postinfection (p.i.), and 1 was sacrificed at 137 days p.i. at the end of its second pregnancy. Evidence of JV was obtained by Vero cell cocultivation in all 14 fetuses harvested (brain and/or spleen) and in 10 of 11 placentas. The results strongly suggest that the attenuated JV strain infected the fetus by the transplacental route, as previously demonstrated for the pathogenic XJ strain. Despite limited sampling, the acute as well as the chronic stage proved viable.

[Development of the infection in guinea pigs infected with the attenuated variant XJO of Junín virus]. / Evolución de la infección en cobayos infectados con la variante atenuada XJO del virus Junín.

As previously shown, the XJO variant of Junin virus (JV) is attenuated and elicits in guinea pigs a lasting humoral response and resistance to the challenge with XJ pathogenic strain, during at least three months. In this paper the long term evolution of guinea pigs inoculated with XJO by im route was studied. Ten animals were infected with 10(3) PFU of XJO at day 0 (group I) and an other 10, at days 0 and 77 (group II). Another 30 guinea pigs were inoculated with 10(2) PFU at day 0 (group III) and 30 at days 0 and 12 (group IV). The animals were observed during 12 months. Circulating complement fixing (CF) and neutralizing (Nt) antibodies were measured at different periods pi in all groups, and lots of four guinea pigs from groups III and IV were challenged with 10(2) PFU of XJ strain at 120, 180, 240 and 360 days pi. Independently of the number of inoculations, the humoral response was similar in the four groups. CF antibodies appeared in all animals around 30 days pi in low values (1:4-1:8) and after a peak, which in a few animals reached 1:32-1:64, returned to previous levels by 12 months pi. Nt antibodies, first detected 15-20 days pi, reached maximum titers by 75-80 days pi, decreasing afterwards to a plateau which persisted throughout the 12 month period (Fig. 1A-B). Probably the continuous presence of antibodies could account for the 100% resistance to the challenge with XJ pathogenic strain shown by these animals (table I).(ABSTRACT TRUNCATED AT 250 WORDS)