Karl M. Johnson

Isolation of the Etiologic Agent of Korean Hemorrhagic Fever

Lung tissues from 73 rodents (Apodemus agrarius coreae) gave specific immunofluorescent reactions when they reacted with sera from patients convalescing from Korean hemorrhagic fever. Similar staaining was observed in the lungs of A. agrarius inoculated with acute-phase sera obtained from two patients with this disease. The unidentified agent was successfully propagated in adult A. agrarius through eight passages representing a cumulative dilution of greater than 10(-17). Experimentally inoculated rodents developed specific fluorescent antigen in the lung, kidney, liver, parotid glands, and bladder. Organs, especially lungs, were positive beginning 10 days and continuing through 69 days after inoculation. The agent could not be cultivated in several types of cell cultures nor in laboratory animals. No fluorescence was observed when infected A. agrarius lung tissues were reacted with antisera to Marburg virus, Ebola virus, and serval arenaviruses. Diagnostic increases in immunofluorescent antibodies occurred in 113 of 116 severe and 11 of 34 milder cases of clinically suspected Korean hemorrhagic fever. Antibodies were present during the first week of symptoms, reached a peak at the end of the second week, and persisted for up to 14 years. Convalescent-phase sera from four persons suffering a similar disease in the Soviet Union were also positive for antibodies.

Lassa fever: Effective therapy with ribavirin

Abstract In a study of Lassa fever in Sierra Leone, West Africa, we identified two variables associated with a high risk of death, and we evaluated the efficacy of ribavirin and Lassa virus-convalescent plasma for the treatment of Lassa fever. A serum aspartate aminotransferase level greater than or equal to 150 IU per liter at the time of hospital admission was associated with a case-fatality rate of 55 percent (33 of 60). Patients with the same risk factor who were treated for 10 days with intravenous ribavirin, begun within the first 6 days after the onset of fever, had a case-fatality rate of 5 percent (1 of 20) (P = 0.0002 by Fishers exact test). Patients whose treatment began seven or more days after the onset of fever had a case-fatality rate of 26 percent (11 of 43) (P = 0.01). Viremia with levels greater than or equal to 10(3.6) TCID50 per milliliter on admission was associated with a case-fatality rate of 76 percent (35 of 46). Patients with this risk factor who were treated with intravenous ribavirin within the first six days after onset of fever had a case-fatality rate of 9 percent (1 of 11) (P = 0.006), whereas those treated after seven days or more of illness had a fatality rate of 47 percent (9 of 19) (P = 0.035). Oral ribavirin was also effective in patients at high risk of death. Lassa-convalescent plasma did not significantly reduce mortality in any of the high-risk groups. We conclude that ribavirin is effective in the treatment of Lassa fever and that it should be used at any point in the illness, as well as for postexposure prophylaxis.

Proposal for a revised taxonomy of the family Filoviridae: classification, names of taxa and viruses, and virus abbreviations

The taxonomy of the family Filoviridae (marburgviruses and ebolaviruses) has changed several times since the discovery of its members, resulting in a plethora of species and virus names and abbreviations. The current taxonomy has only been partially accepted by most laboratory virologists. Confusion likely arose for several reasons: species names that consist of several words or which (should) contain diacritical marks, the current orthographic identity of species and virus names, and the similar pronunciation of several virus abbreviations in the absence of guidance for the correct use of vernacular names. To rectify this problem, we suggest (1) to retain the current species names Reston ebolavirus, Sudan ebolavirus, and Zaire ebolavirus, but to replace the name Cote d’Ivoire ebolavirus [sic] with Taï Forest ebolavirus and Lake Victoria marburgvirus with Marburg marburgvirus; (2) to revert the virus names of the type marburgviruses and ebolaviruses to those used for decades in the field (Marburg virus instead of Lake Victoria marburgvirus and Ebola virus instead of Zaire ebolavirus); (3) to introduce names for the remaining viruses reminiscent of jargon used by laboratory virologists but nevertheless different from species names (Reston virus, Sudan virus, Taï Forest virus), and (4) to introduce distinct abbreviations for the individual viruses (RESTV for Reston virus, SUDV for Sudan virus, and TAFV for Taï Forest virus), while retaining that for Marburg virus (MARV) and reintroducing that used over decades for Ebola virus (EBOV). Paying tribute to developments in the field, we propose (a) to create a new ebolavirus species (Bundibugyo ebolavirus) for one member virus (Bundibugyo virus, BDBV); (b) to assign a second virus to the species Marburg marburgvirus (Ravn virus, RAVV) for better reflection of now available high-resolution phylogeny; and (c) to create a new tentative genus (Cuevavirus) with one tentative species (Lloviu cuevavirus) for the recently discovered Lloviu virus (LLOV). Furthermore, we explain the etymological derivation of individual names, their pronunciation, and their correct use, and we elaborate on demarcation criteria for each taxon and virus.

A plaque neutralization method for arboviruses.

Summary A method for production of plaques by arboviruses in small wells of disposable plastic trays is described. Each of 19 viruses from Central or South America produced plaques in MA-111 and VERO cell lines. Optimum conditions for various agents were determined. The method was shown to give reliable measurement of VEE virus antibodies in sera from humans with naturally acquired infections.

Filoviridae: a taxonomic home for Marburg and Ebola viruses?

Filoviridae: a Taxonomic Home for Marburg and Ebola Viruses ? M.P. Kiley E.T.W. Bowen G.A. Eddy M. Isaäcson K.M. Johnson J.B. McCormick F.A. Murphy S.R. Pattyn D. Peters O.W. Prozesky R.L. Regnery D.I.H. Simpson W. Slenczka P. Sureau G. van der Groen P.A. Webb H. Wulff Center for Infectious Diseases, Centers for Disease Control, Atlanta, Ga., USA; PHLS Centre for Applied Microbiology and Research, Porton Down, Salisbury, Wiltshire, UK; US Army Medical Research Institute for Infectious Diseases, Ft. Detrick, Frederick, Md., USA; The South African Institute for Medical Research, Johannesburg, South Africa; Colorado State University, College of Veterinary Medicine and Biomedical Sciences, Ft. Collins, Col., USA;Prins Leopold Instituut voor Tropische Geneeskunde, Antwerpen, Belgium; Bernard-Nocht-Institut für Schiffsund Tropenkrankheiten, Abteilung für Virologie, Hamburg, FRG; National Institute for Virology, Sandringham, Transvaal, South Africa;Hygiene-Institut der Universität, Marburg, FRG; Institut Pasteur, Paris, France

Potential mammalian filovirus reservoirs

Biologic principles and explicit assumptions reduce the range of possibilities in identifying the reservoir of filoviruses

A Search for Ebola Virus in Animals in the Democratic Republic of the Congo and Cameroon: Ecologic, Virologic, and Serologic Surveys, 1979–1980

More than 30 years after the first outbreak of Marburg virus disease in Germany and Yugoslavia and 20 years after Ebola hemorrhagic fever first occurred in central Africa, the natural history of filoviruses remains unknown. In 1979 and 1980, animals in the Democratic Republic of the Congo and Cameroon were collected during the dry season near the site of the 1976 Ebola hemorrhagic fever epidemic. The study objectives were to identify local animals and search for evidence of Ebola virus in their tissues. A total of 1664 animals representing 117 species was collected, including >400 bats and 500 rodents. Vero and CV-1 cells and IFA and RIA were used for virus and antibody detection, respectively. No evidence of Ebola virus infection was found. This study was limited in time and animal collections and excluded insects and plants. Long-term, prospective, multidisciplinary comparative studies will yield more information than will repeat short forays on the ecology of filoviruses.

Virus nomenclature below the species level: a standardized nomenclature for natural variants of viruses assigned to the family Filoviridae

The task of international expert groups is to recommend the classification and naming of viruses. The International Committee on Taxonomy of Viruses Filoviridae Study Group and other experts have recently established an almost consistent classification and nomenclature for filoviruses. Here, further guidelines are suggested to include their natural genetic variants. First, this term is defined. Second, a template for full-length virus names (such as “Ebola virus H.sapiens-tc/COD/1995/Kikwit-9510621”) is proposed. These names contain information on the identity of the virus (e.g., Ebola virus), isolation host (e.g., members of the species Homo sapiens), sampling location (e.g., Democratic Republic of the Congo (COD)), sampling year, genetic variant (e.g., Kikwit), and isolate (e.g., 9510621). Suffixes are proposed for individual names that clarify whether a given genetic variant has been characterized based on passage zero material (-wt), has been passaged in tissue/cell culture (-tc), is known from consensus sequence fragments only (-frag), or does (most likely) not exist anymore (-hist). We suggest that these comprehensive names are to be used specifically in the methods section of publications. Suitable abbreviations, also proposed here, could then be used throughout the text, while the full names could be used again in phylograms, tables, or figures if the contained information aids the interpretation of presented data. The proposed system is very similar to the well-known influenzavirus nomenclature and the nomenclature recently proposed for rotaviruses. If applied consistently, it would considerably simplify retrieval of sequence data from electronic databases and be a first important step toward a viral genome annotation standard as sought by the National Center for Biotechnology Information (NCBI). Furthermore, adoption of this nomenclature would increase the general understanding of filovirus-related publications and presentations and improve figures such as phylograms, alignments, and diagrams. Most importantly, it would counter the increasing confusion in genetic variant naming due to the identification of ever more sequences through technological breakthroughs in high-throughput sequencing and environmental sampling.

Virus Isolations from Human Cases of Hemorrhagic Fever in Bolivia

Summary Five serologically similar virus strains were recovered in San Joaquin, Bolivia, in 1963 from humans suffering from a newly recognized febrile disease with hemor-rhagic manifestations. Three isolates were from splenic tissue obtained at autopsy and 2 from blood specimens taken from acutely ill patients. The prototype strain (Carvallo) was pathogenic for newborn mice and hamsters, produced cytopathic effects in WI-26 cell cultures and plaques in MA-111 cell cultures, was inactivated by chloroform, and was estimated to be 180 mμ or less in size. It was nearly indistinguishable from Junin and Tacaribe viruses by complement fixation test, but completely distinct from these agents by neutralization test. It is proposed that these strains collectively be named Ma-chupo Virus. The authors are indebted to Drs. Luis Valverde Ch. and Hugo Garron, Hemorrhagic Fever Commission, Ministry of Health, Bolivia, to Dr. Conrad Yunker, Rocky Mountain Laboratory of this Institute, and to Dr. J. P. Woodall, East African Medical Research Institute, Entebbe, Uganda, for their unstinting help in the work in San Joaquin. Mr. John Vogel, Mr. Angel Muñoz, Miss Elizabeth Earley, Mr. Fred Mitchell, Miss Darlene Del Nero and Mr. G. R. Rankin contributed valuable technical assistance.

Clinical and Serologic Responses in Volunteers Given Vacuolating Virus (SV40) by Respiratory Route

Summary SV40 virus present as a contaminant in a pool of respiratory syncitial virus prepared in cultures of rhesus monkey kidney cells was inoculated by the respiratory route into 35 adult volunteers: 8 of these received SV40 virus preparation in which the RS virus component was neutralized by addition of RS antiserum. None of the test subjects developed signs or symptoms attributable to inhalation of SV40. SV40 virus was recovered from throat swab specimens of 3 of the volunteers 7 or 11 days after exposure. SV40 neutralizing antibody in titers ranging from 1:5 to 1:80 appeared in the blood of 22 of the 35 test subjects.