Argentinian Hemorrhagic Fever Research Articles

South American Hemorrhagic Fever viruses and the cutting edge of the vaccine and antiviral development

South American Hemorrhagic Fever is caused by the Arenavirus, which belong to the Family Arenaviridae, genus mammarenavirus, infection at South America. South American Hemorrhagic Fever includes 1. Argentinian Hemorrhagic fever caused by Junin virus, 2. Brazilian hemorrhagic fever caused by Sabia virus, 3. Venezuelan Hemorrhagic fever caused by Guanarito virus, 4. Bolivian Hemorrhagic fever caused by Machupo virus, and 5. Unassigned hemorrhagic fever caused by Chapare virus. These viruses are classified in New World (NW) Arenavirus, which is different from Old World Arenavirus (ex. Lassa virus), based on phylogeny, serology, and geographic differences. In this review, the current knowledge of the biology and the development of the vaccines and antivirals of NW Arenaviruses which cause South American Hemorrhagic Fever will be described.

Development of a Reverse Genetic System to Generate Recombinant Chimeric Tacaribe Virus that Expresses Junín Virus Glycoproteins.

Mammarenaviruses are enveloped and segmented negative-stranded RNA viruses that comprise several pathogenic members associated with severe human hemorrhagic fevers. Tacaribe virus (TCRV) is the prototype for the New World group of mammarenaviruses and is not only naturally attenuated but also phylogenetically and antigenically related to all South American pathogenic mammarenaviruses, particularly the Junín virus (JUNV), which is the etiological agent of Argentinian hemorrhagic fever (AHF). Moreover, since TCRV protects guinea pigs and non-human primates from lethal challenges with pathogenic strains of JUNV, it has already been considered as a potential live-attenuated virus vaccine candidate against AHF. Here, we report the development of a reverse genetic system that relies on T7 polymerase-driven intracellular expression of the complementary copy (antigenome) of both viral S and L RNA segments. Using this approach, we successfully recovered recombinant TCRV (rTCRV) that displayed growth properties resembling those of authentic TCRV. We also generated a chimeric recombinant TCRV expressing the JUNV glycoproteins, which propagated similarly to wild-type rTCRV. Moreover, a controlled modification within the S RNA 5′ non-coding terminal sequence diminished rTCRV propagation in a cell-type dependent manner, giving rise to new perspectives where the incorporation of additional attenuation markers could contribute to develop safe rTCRV-based vaccines against pathogenic mammarenaviruses.

Protocol for the Production of a Vaccine Against Argentinian Hemorrhagic Fever.

Argentinian hemorrhagic Fever (AHF) is a febrile, acute disease caused by Junín virus (JUNV), a member of the Arenaviridae. Different approaches to obtain an effective antigen to prevent AHF using complete live or inactivated virus, as well as molecular constructs, have reached diverse development stages. This chapter refers to JUNV live attenuated vaccine strain Candid #1, currently used in Argentina to prevent AHF. A general standardized protocol used at Instituto Nacional de Enfermedades Virales Humanas (Pergamino, Pcia. Buenos Aires, Argentina) to manufacture the tissue culture derived Candid #1 vaccine is described. Intermediate stages like viral seeds and cell culture bank management, bulk vaccine manufacture, and finished product processing are also separately presented in terms of Production and Quality Control/Quality Assurance requirements, under the Adminitracion Nacional de Medicamentos, Alimentos y Tecnología Medica (ANMAT), the Argentine national regulatory authority.

Designing arenaviral vaccines.

Several hemorrhagic fevers, including Lassa fever (LF; Lassa virus), Argentinian hemorrhagic fever (AHF; Junin virus), Bolivian hemorrhagic fever (BHF; Machupo virus) and Venezuelan hemorrhagic fever (VHF; Guanarito virus) are caused by arenaviruses. These diseases can be devastating, and often lethal. LCMV, the prototype of the Arenaviridae, can cause aseptic meningitis, and is a known teratogen. Despite the pathogenicity of the arenaviruses, to date only one vaccine (against AHF) has been evaluated in humans. In this chapter we shall review the design of arena viral vaccines. The rational design of a vaccine requires that we consider (a) the viruses themselves, (b) the route(s) by which they infect the unfortunate host, (c) the host immune response induced, (d) possible negative consequences of immunization, and (e) the vaccine approaches available. Some of these topics are discussed in detail in other chapters of this volume, and thus will be described quite briefly below.

Molecular approaches for the treatment of hemorrhagic fever virus infections

Viruses causing hemorrhagic fevers in man belong to the following virus groups: togavirus (Chikungunya), flavivirus (dengue, yellow fever, Kyasanur Forest disease, Omsk hemorrhagic fever), arenavirus (Argentinian hemorrhagic fever, Bolivian hemorrhagic fever, Lassa fever), filovirus (Ebola, Marburg), phlebovirus (Rift Valley fever), nairovirus (Crimian-Congo hemorrhagic fever) and hantavirus (hemorrhagic fever with renal syndrome, nephropathic epidemia). Hemorrhagic fever virus infections can be approached by different therapeutic strategies: (i) vaccination; (ii) administration of high-titered antibodies; and (iii) treatment with antiviral drugs. Depending on the molecular target of their interaction, antiviral agents could be classified as follows: IMP dehydrogenase inhibitors (i.e., ribavirin and its derivatives); OMP decarboxylase inhibitors (i.e., pyrazofurin); CTP synthetase inhibitors (i.e., cyclopentylcytosine and cyclopentenylcytosine); SAH hydrolase inhibitors (i.e., neplanocin A); polyanionic substances (i.e., sulfated polymers); interferon and immunomodulators.

Junin virus‐induced suppressor cells are effective only on the efferent limb of the delayed‐type hypersensitivity response

Junin virus (JV), the etiological agent of Argentinian hemorrhagic fever, induces high mortality in the suckling BALB/c mouse, which correlates with delayed-type hypersensitivity (DTH)-like immune response. In contrast, the adult mouse is resistant to infection, and no DTH response can be detected. An antigen-nonspecific DTH suppressor T-cell activity induced by JV has been described that may be related to adult mouse survival. In this report, we present evidence supporting the inability of such cells, identified here as bearing the L3T4 marker, to affect the normal establishment of a DTH reaction. In the same form, virus-induced suppressor cells were unable to alter the expression of DTH effector cells in the absence of antigen-specific DTH suppressor cells. Besides, we found that a single high dose (200 mg/kg) of cyclophosphamide before or after JV inoculation was unable to alter the activity of virus-induced suppressor cells.

Frequency of rodents in habitats near Pergamino, Argentina, as related to Junín virus.

A study of rodent frequency in various habitats in the Pergamino area revealed that rodent density is greatest along railroad rights-of-way, roadsides, and fence rows. Cornfields and pastures, although the principal form of land use in the region, are not as important to annual production of rodents as the above areas. However, weedy cornfields do help preserve the lives of young rodents as they disperse from the favored linear habitats, and thus probably serve as important links in the infection of man with Junín virus, the cause of Argentinian hemorrhagic fever. These findings indicate that future control measures should be aimed at curtailing rodent reproduction along the linear habitats to prevent their spread into the cornfields.

Growth of Junin virus, the etiological agent of argentinian hemorrhagic fever, in cell cultures

Propagation of Junin virus, the etiological agent of Argentinian hemorrhagic fever, has been studied in a variety of cell cultures. One line of African green monkey kidney cells (Vero) at the 107th to 165th passage levels supported the multiplication of the virus and developed a marked cytopathic effect (CPE), while no CPE appeared in another line (BS-C-1) at the 34th passage level. CPE was markedly enhanced by rolling the cultures, and the cytocidal nature of virus replication was markedly more pronounced under these conditions. Junin virus also produced well-defined plaques in monolayer cultures of Vero cells under agar overlay. Virus assays obtained by titration endpoint of CPE or by plaque counts in Vero cells were in almost all instances higher than those obtained by titration in suckling mice. A linear relationship was observed between plaque counts and virus concentration. Maximum adsorption was obtained by 120 minutes incubation at 37°C. When the cultures were infected with <0.001 PFU per cell, the maximum virus titer was obtained on the 5th day after inoculation.

Epidemic Hemorrhagic Fever in Bolivia

Summary The 1962 epidemic of a febrile disease with hemorrhagic manifestations in Bolivia was apparently due to infection by a virus related to Junin virus, the etiological agent of Argentinian hemorrhagic fever. Laboratory evidence was obtained by complement fixation tests using the Junin antigen and sera from several small population groups in and around the epidemic areas of northeast Bolivia. Distribution and concentration of complement fixing antibody were related to recent illness, and serological conversion was demonstrated in the three pairs of sera available from typical cases of the Bolivian disease.

Study of the Antigenic Relationships between Junín Virus, the Etiological Agent of Argentinian Hemorrhagic Fever, and Other Arthropod-Borne Viruses

Summary Strains XJ, R and F of Junin virus, which were isolated by two different groups of investigators, have been compared for the first time and been found to be indistinguishable by complement-fixation test. Neutralization test comparisons are pending. Junin and Tacaribe virus from Trinidad have been shown to be closely related by complement-fixation test, although distinguishable on the basis of serum titers. In limited studies by neutralization test they were easily separable. It is of interest that sera from persons convalescing from Argentinian hemorrhagic fever fixed complement in the presence of Tacaribe antigen. No cross-reactions were observed between Junin complement-fixing antigens and immune sera for 139 other arthropod-borne viruses, or between Junin antisera and hemagglutinating antigens from 41 arboviruses. Junin antigens likewise failed to react by complement-fixation test with various non-arboviruses including encephalomyocarditis, mouse encephalomyelitis and several rickettsiae. From descriptions in the literature there appears to be a degree of clinical resemblance between Korean and Argentinian hemorrhagic fevers; sera from six human patients convalescing from the former failed to react with a Junin complement-fixing antigen. Junin antigens with consistently good complement-fixing titers between 1:32 and 1:128 were obtained by harvesting infected mouse brain tissue 7 or 8 days after inoculation. A growth curve study showed maximal virus titer at that time in the absence or near absence of signs of illness. Junin strain XJ, which originally was highly pathogenic for guinea pigs by the intraperitoneal route of inoculation, appeared to have lost its pathogenicity for guinea pigs by that route after about 40 passages in newborn mice.

Propagation of Junin virus, the etiological agent of Argentinian hemorrhagic fever, in HeLa cell cultures.

SummaryJunin virus, the etiological agent of Argentinian hemorrhagic fever has been propagated serially in HeLa cell cultures. Appropriate cell viability during the long experimental period was obtained by the use of a suitable combination of growth-promoting and maintenance media as well as by frequent fluid changes during the period of viral synthesis.A characteristic cytopathic effect was observed during the 1st passage and did not change during 10 consecutive transfers of the agent. Evidence that the cytopathogenic agent was Junin virus was derived from fluorescent antibody studies and from neutralization tests with sera from animals immunized with the virus propagated in newborn mice. In cell cultures, Junin virus was inactivated by sodium desoxycholate, a property common to all arthropod-borne viruses.