RESUMEN
Thirty-seven house mice (Mus musculus, Rodentia) caught in different localities in French Guiana were screened to investigate the presence of lymphocytic choriomeningitis mammarenavirus (LCMV). Two animals trapped in an urban area were found positive, hosting a new strain of LCMV, that we tentatively named LCMV "Comou". The complete sequence was determined using a metagenomic approach. Phylogenetic analyses revealed that this strain is related to genetic lineage I composed of strains inducing severe disease in humans. These results emphasize the need for active surveillance in humans as well as in house mouse populations, which is a rather common rodent in French Guianese cities and settlements.
Asunto(s)
Coriomeningitis Linfocítica/veterinaria , Virus de la Coriomeningitis Linfocítica/clasificación , Virus de la Coriomeningitis Linfocítica/aislamiento & purificación , Enfermedades de los Roedores/virología , Animales , Guyana Francesa , Genoma Viral , Virus de la Coriomeningitis Linfocítica/genética , Metagenómica/métodos , Ratones , FilogeniaRESUMEN
The activity of LCM virus was first reported in Argentina at the beginning of the seventies and only five strains have been isolated from rodents Mus domesticus and two from humans. The objective of this paper was to find differential biological characteristics of Argentine strains of LCM virus comparing them in relation to the historical strains WE and Armstrong. Regarding the results obtained in tissue culture, when L 929 cells were used, plaque forming units (PFU) were obtained with human and mouse strains, whilst on Vero cells only human strains developed PFU. Differentials characteristics of historical and Argentine strain's plates were not found, neither differences related to the strain's origin. Neither historical nor Argentine strains were lethal to new-born mice giving a persistent infection, that was demonstrated when we inoculated new-born mouse by intracranial route with different strains of LCM virus and virus was isolated from brains harvested at different days post inoculation. The only exception was Cba An 13065 strain that exhibited virulence in new-born mice, only with 0.026 PFU was obtained 1 DL50. All the strains resulted lethal to adult mice. The mouse strains were more virulent than human strains, being Cba An 13065 the most virulent. These results demonstrate a different behavior in tissue culture between human and mouse strains and allow the identification of virulence markers by intracranial inoculation into new-born or adult mice.
Asunto(s)
Coriomeningitis Linfocítica/virología , Virus de la Coriomeningitis Linfocítica/patogenicidad , Roedores/virología , Animales , Argentina , Biomarcadores , Línea Celular , Chlorocebus aethiops , Interacciones Huésped-Patógeno , Humanos , Huésped Inmunocomprometido , Coriomeningitis Linfocítica/inmunología , Virus de la Coriomeningitis Linfocítica/aislamiento & purificación , Ratones , Roedores/genética , Especificidad de la Especie , Células Vero , VirulenciaRESUMEN
La actividad del virus LCM fue informada en Argentina a comienzos de la década del 70 y sólo han sido aisladas cinco cepas a partir del roedor Mus domesticus y dos de humanos. El objetivo de este trabajo consistió en investigar características biológicas de las cepas argentinas de virus LCM para compararlas entre sí y respecto a las cepas históricas WE y Armstrong. En células L 929 se obtuvieron placas bajo agarosa tanto con las cepas humanas como con las cepas de ratón, pero en células Vero sólo se obtuvieron placas con las cepas humanas. No se observó ninguna característica morfométrica de las placas que distinguiera nítidamente a las cepas históricas de las cepas argentinas, ni se observaron diferencias que se relacionen con las especies de origen de las cepas. Las cepas históricas y las cepas argentinas no fueron letales para ratón recién nacido (rrn) generando una infección persistente, según se comprobó al inocular ratones recién nacidos (rrn) por vía intracerebral con cepas de virus LCM y detectarse virus en los cerebros cosechados a diferentes días post inoculación. La única excepción fue la cepa Cba An 13065 que resultó virulenta para rrn ya que con sólo 0.026 UFP se logró 1 DL50. Todas las cepas resultaron letales en ratón adulto (rad), siendo las cepas de ratón más virulentas que las cepas de humanos. Estos resultados permitieron evidenciar el diferente comportamiento en cultivos celulares de las cepas de ratón con respecto a las cepas humanas, e identificar marcadores de virulencia mediante la respuesta a la inoculación por vía intracerebral del rad y del rrn.
The activity of LCM virus was first reported in Argentina at the beginning of the seventies and only five strains have been isolated from rodents Mus domesticus and two from humans. The objective of this paper was to find differential biological characteristics of Argentine strains of LCM virus comparing them in relation to the historical strains WE and Armstrong. Regarding the results obtained in tissue culture, when L 929 cells were used, plaque forming units (PFU) were obtained with human and mouse strains, whilst on Vero cells only human strains developed PFU. Differentials characteristics of historical and Argentine strain's plates were not found, neither differences related to the strain's origin. Neither historical nor Argentine strains were lethal to new-born mice giving a persistent infection, that was demonstrated when we inoculated new-born mouse by intracranial route with different strains of LCM virus and virus was isolated from brains harvested at different days post inoculation. The only exception was Cba An 13065 strain that exhibited virulence in new-born mice, only with 0.026 PFU was obtained 1 DL50. All the strains resulted lethal to adult mice. The mouse strains were more virulent than human strains, being Cba An 13065 the most virulent. These results demonstrate a different behavior in tissue culture between human and mouse strains and allow the identification of virulence markers by intracranial inoculation into new-born or adult mice.
Asunto(s)
Humanos , Animales , Ratones , Coriomeningitis Linfocítica/virología , Virus de la Coriomeningitis Linfocítica/patogenicidad , Roedores/virología , Argentina , Biomarcadores , Línea Celular , Interacciones Huésped-Patógeno , Huésped Inmunocomprometido , Coriomeningitis Linfocítica/inmunología , Virus de la Coriomeningitis Linfocítica/aislamiento & purificación , Roedores/genética , Especificidad de la Especie , VirulenciaRESUMEN
The activity of lymphocytic choriomeningitis virus (LCMv) in Argentina has been previously reported on the basis of serological evidence in rodents and humans and the isolation of only one strain of LCMv from a Mus domesticus captured in the province of Córdoba. The aim of this paper was to register patients with serological diagnosis of LCM, to isolate and to identify human strains of LCMv in Argentina. During the last 19 years, 15 cases were diagnosed as LCM by immunoflourescent indirect assay (IFI) and enzyme-linked immunosorbent assay (ELISA) but when neutralizing assay (NT) was incorporated, eight cases were classified as confirmed, three as probable and four as negative. The geographic distribution of the cases included three provinces: Córdoba, Buenos Aires and Santa Fe. Viral isolation was attempted in five patients classified as confirmed and only two resulted positive (P5226 and P8573). They were identified as LCMv by IFI and NT. The coexistence of LCMv with other arenaviruses, such as Junin and Oliveros viruses, in the same area, raises the probability of interactions between them, which could modify the virulence and/or pathogenicity for humans associated to genomic changes. Future studies of antigenic, genomic and virulence variability of different Argentine strains of LCMv, as well as the systematic search for human infection, will contribute to define the importance of this viral agent in our country and to implement control measures.
Asunto(s)
Coriomeningitis Linfocítica/diagnóstico , Virus de la Coriomeningitis Linfocítica/aislamiento & purificación , Animales , Argentina , Ensayo de Inmunoadsorción Enzimática , Técnica del Anticuerpo Fluorescente Indirecta/métodos , Humanos , Coriomeningitis Linfocítica/sangre , Coriomeningitis Linfocítica/virología , Pruebas de Neutralización , Conejos , RatasRESUMEN
The active coexistence of two pathogenic arenaviruses, Junin (JUNV) and lymphocytic choriomeningitis (LCMV), in the same region of Argentina, has been known since the early 70's, and records of clinical and subclinical human infections by one and/or the other agent have been continuously produced for the last 25 years. Anti-LCMV antibody is currently searched only by indirect immunofluorescence, a test that shows cross reactions among a number of arenaviruses yielding, in the cases of LCMV and JUNV consecutive infections, a concomitant seroconversion for both viruses, as an inconclusive diagnostic result. In contrast, neutralization (NT) tests reveal arenavirus antibodies directed to unique epitopes on these virus envelopes, thus allowing to disclose the sequence in the cases of consecutive infections. In this paper, the characteristics of neutralization (NT) test for LCMV in cell cultures are described, as well as its performance in the field diagnosis of LCMV human infections. The native LCMV strain Cba An 13065 was inoculated on L-929 cell (ATCC CCL 1), and procedures were followed to perform a constant virus-variable serum NT test. Final points of sera titrations were expressed as the maximal serum dilution that yielded 75% of pfu inhibition. This NT test was assayed on paired serum samples of 36 patients with confirmed Argentine hemorrhagic fever (AHF) (a disease caused by JUNV), who had had a known previous contact with LCMV through IFI. The use of this one test led to confusing diagnosis of the disease due to concomitant seroconversion for JUNV and LCMV. By using NT test, it was shown that: some of them were possibly not infected by LCMV, and that 30/36 cases (83.3%) had a pre-existing level of LCMV antibody, with titers in the range of 5 to 640, remaining unchanged 60 days after the clinical AHF. This shows that NT antibodies to LCMV are not influenced by the outcome of the immune response to JUNV, thus confirming the efficiency of NT test as identificator among arenaviruses. To assess the performance of this NT test in individuals having only IFI antibodies to LCMV, 126 serum samples obtained through serological surveillance in a rural area of Argentina, were used. It was found that NT had improved coincidence with IFI as IFI titers increased. Interpretations were based on the pan-arenavirus antibody response obtained by using IFI as the only test. Results presented herein prove that the described NT test is a valuable tool for the detection of LCMV infections, particularly when a previous infection with LCMV has to be demonstrated during the acute phase of Argentine hemorrhagic fever.
Asunto(s)
Anticuerpos Antivirales/sangre , Fiebre Hemorrágica Americana/diagnóstico , Virus Junin/inmunología , Coriomeningitis Linfocítica/diagnóstico , Virus de la Coriomeningitis Linfocítica/inmunología , Pruebas de Neutralización , Enfermedad Aguda , Animales , Anticuerpos Antivirales/inmunología , Argentina/epidemiología , Convalecencia , Técnica del Anticuerpo Fluorescente Indirecta , Fiebre Hemorrágica Americana/epidemiología , Fiebre Hemorrágica Americana/virología , Humanos , Virus Junin/crecimiento & desarrollo , Virus Junin/aislamiento & purificación , Células L/virología , Coriomeningitis Linfocítica/epidemiología , Coriomeningitis Linfocítica/virología , Virus de la Coriomeningitis Linfocítica/crecimiento & desarrollo , Virus de la Coriomeningitis Linfocítica/aislamiento & purificación , Ratones , Estudios Seroepidemiológicos , Cultivo de VirusRESUMEN
The activity of lymphocytic choriomeningitis virus (LCMv) in Argentina has been previously reported on the basis of serological evidence in rodents and humans and the isolation of only one strain of LCMv from a Mus domesticus captured in the province of Cordoba. The aim of this paper was to register patients with serological diagnosis of LCM, to isolate and to identify human strains of LCMv in Argentina. During the last 19 years, 15 cases were diagnosed as LCM by immunoflourescent indirect assay (IFI) and enzyme-linked immunosorbent assay (ELISA) but when neutralizing assay (NT) was incorporated, eight cases were classified as confirmed, three as probable and four as negative. The geographic distribution of the cases included three provinces: Cordoba, Buenos Aires and Santa Fe. Viral isolation was attempted in five patients classified as confirmed and only two resulted positive (P5226 and P8573). They were identified as LCMv by IFI and NT. The coexistence of LCMv with other arenaviruses, such as Junin and Oliveros viruses, in the same area, raises the probability of interactions between them, which could modify the virulence and/or pathogenicity for humans associated to genomic changes. Future studies of antigenic, genomic and virulence variability of different Argentine strains of LCMv, as well as the systematic search for human infection, will contribute to define the importance of this viral agent in our country and to implement control measures. (Au)
Asunto(s)
Humanos , Animales , Ratas , Conejos , Virus de la Coriomeningitis Linfocítica/aislamiento & purificación , Coriomeningitis Linfocítica/diagnóstico , Coriomeningitis Linfocítica/sangre , Coriomeningitis Linfocítica/virología , Técnica del Anticuerpo Fluorescente Indirecta/métodos , Ensayo de Inmunoadsorción Enzimática , Pruebas de Neutralización , ArgentinaRESUMEN
The biogeographical examination of rodent faunas associated with arenaviruses reveals two distinct patterns. Lymphocytic choriomeningitis (LCM) virus is associated primarily with a single murid species, Mus musculus, although it is also known to cause laboratory infections in other species. On the other hand, the arenaviruses from the Western hemisphere are associated exclusively with a large and diverse group of cricetid rodents. Studies to date, although limited, have not demonstrated their association with any other rodent groups, although in South America alone at least twelve other rodent families are known. Evidence at the present time indicates that Lassa virus is only associated with a common African rodent, Mastomys natalensis. From this limited evidence it is as yet difficult to determine whether Lassa virus will follow the pattern of the South American arenaviruses, most of which are known from several species of rodents, or that of LCM virus, which appears to be associated with only a single rodent species. In this paper, the history and structure of South American, Eurasian, and African rodent faunas are described.