Isolation of a virus strain from Argas persicus ticks

A previously undescribed virus was isolated from Argas persicus ticks collected on sentinel chicken in western Slovakia. The strain was lethal for suckling mice only after intracerebral inoculation. No symptoms were induced in adult mice. The virus strain was insensitive to sodium deoxycholate and resistant to ether treatment. An antigen prepared from the virus did not agglutinate goose or human O erythrocytes. The single strain obtained in 1976 appeared to be untrelated to a large number of known arboviruses when tested by the complement-fixation reaction.

Lassa virus antibodies in hospital personnel in western Liberia

The sera of 844 Liberian hospital staff memebers were positive for Lassa Virus (LV) antibodies in a survey using the indirect fluorescent antibody technique (IFAT). In two hospitals in Lofa County near the Sierra Leone border, the prevalence, 15.4%, was significantly higher than the 8.4% in seven others. There were near differences between the prevalence among laboratory workers, 15.3%, and other workers, 7.7%, and between midwifery students, 21.2%, and midwives, 4.2%, suggesting their infection from patients or their blood products. However, the over-all prevalence among those with patient contacts was the same as that among those without direct patient contact; most LV infections were apparently acquired from sources other than patients in hospital. This finding, the lack of evidence of hospital outbreaks and the presence of comparable prevalences in all age groups suggest that LV infections occur on a continuing basis in this population. In one hospital the comparison of the results of IFAT and complement fixation tests revealed some who reacted by one technique and not by the other. In one person the titre by IFAT had dropped from 1:32 to undetectable levels in two years. This finding prompts caution in the interpretation of results.

Isolation of Dhori virus from Hyalomma marginatum ticks in Portugal

An agent pathogenic for mice was isolated from Hyalomma m. marginatum ticks collected from cattle in southern Portugal. Serologically, the agent was indistinguishable from Dhori virus, an antigenically ungrouped virus isolated in India.

Antibodies against arboviruses in postencephalitic and idiopathic Parkinson's disease

Serum and CSF from patients with classic von Economo's postencephalitic Parkinson's disease, idiopathic Parkinson's disease and non-Parkinsonian neurological controls were tested for hemagglutination-inhibition antibodies to 17 arboviruses. All 35 CSF specimens from patients with idiopathic Parkinson's disease and controls were negative (ie, no inhibition of hemagglutination) with all the antigens. Of the total of 124 serums from the three study groups, 105 were also negative with all antigens tested. The only positive results were given by 19 serum specimens against one or more of group B arbovirus antigens, and/or against Batai and western equine encephalomyelitis antigens. There were no definitive differences in the distribution of these positive serum titers among controls, idiopathic Parkinson's, and postencephalitic Parkinson's cases. A causal relationship of the arboviruses tested with either the classical postencephalitic or idiopathic Parkinson's disease is not supported by the results of this study.

Crimean-congo hemorrhagic fever, Thogoto, dugbe, and Jos viruses isolated from ixodid ticks in Ethiopia

From 1974 through 1976, U.S. Naval Medical Research Unit No. 5 isolated 25 strain of tick-borne virus in infant mice from 410 pools containing over 6,000 ticks, and one strain from a bird and one strain from a rodent collected in central and southern Ethiopia. Of these, 17 were identified as known viruses previously found in West Central and East Africa. There were 8 strains of Jos virus from Amblyomma ticks; 7 strains of Dugbe virus from a bird, a rodent and from ticks; 1 strains of Crimean-Congo hemorrhagic fever virus and 1 strain of Thogoto virus from ticks.

Enhanced resistance against Junin virus infection induced by Corynebacterium parvum

The effects of intraperitoneal administration of Corynebacterium parvum on the course of Junin virus infection in mice were investigated. This treatment produced enhanced resistance to the virus infection, evidenced by an increase in both survival times and the proportion of survivors. The protective effect was dependent upon the dose of C. parvum, and 280 mug/g of body weight was found to be the optimal dose. In various experiments, about 80% of the infected animals receiving this dose survived, whereas survival ranged between 0 and 20% among untreated infected mice. Maximal protection was afforded by C. parvum when administered simultaneously with the virus. A smaller but significant degree of resistance was induced by C. parvum given 3 or 6 days after infection. C. parvum injected before infection was ineffective. Viral titers measured in the brains of C. parvum-treated and untreated mice at various times after infection were found to be comparable. In addition, there were no significant differences between circulating-antibody titers measured either by neutralization tests or by complement fixation. Depression of the reticuloendothelial system by treatment with silica particles also resulted in enhanced resistance to Junin virus infection, suggesting that the protective effect of C. parvum is not likely to be due merely to its capacity to stimulate macrophages. The present data, highlighting that the presence of high titers of Junin virus and disease do not necessarily correlated, suggest that in mice this disease is not the consequence of cell damage caused directly by the virus but of a still undefined indirect mechanism induced by the virus, not necessarily mediated by macrophages.

Togaviridae

The family Togaviridae is described; it contains four genera--Alphavirus, Flavivirus, Pestivirus and Rubivirus--and additional members. The main characteristics of the family are as follows: single-stranded, linear RNA, molecular weight about 4 X 10(6). Virions have isometric nucleocapsids surrounded by a lipoprotein envelope containing host cell lipid and virus-specified polypeptides including one or more glycopeptides. Virions yield infectious RNA. There are at least 80 members; all the alphaviruses and most flaviviruses are arboviruses in the biological sense.

Sunday Canyon virus, a new ungrouped agent from the tick Argas (A.) cooleyi in Texas

A new arbovirus was isolated from Texas, U.S.A., populations of the Cliff Swallow parasits Argas (Argas) cooleyi Kohls and Hoogstraal, 1960. The virus, named Sunday Canyon, is serological urelated to any of 185 arbovirus strains or 20 other viral agents with which it was compared. Morphologically it resembles Bunyamwera viruses and, in common with them, is sensitive to lipid solvents and acid pH, and apparently possesses RNA. Although considerably resistant to a temperature of 41.5 degrees C, it rapidly loses infectivity when incubated at 56 degrees C. It is lethal for newborn white mice and infective for the Vero and Antheraea eucalypti cell lines. Sundays Canyon virus is the second tick-associated, Bunyamwera virus-like agent known from North America and the third virus to be reported from A. cooleyi in Texas.

Eyach--an arthropod-borne virus related to Colorado tick fever virus in the Federal Republic of Germany

From Ixodes ricinus ticks collected in a tick-borne encephalitis focus in Baden-Württemberg, an agent pathogenic exclusively for suckling mice was isolated. Obviously a virus, it passed membrane filters with a pore width of 200 nm. It was resistant to ether and sodium deoxycholate, but not to chloroform. In the complement fixation test it showed a close, and in the neutralisation test a more one-sided relationship to Colorado tick fever virus.

International arbovirus research

International cooperation in arbovirus research became increasingly prominent shortly after it was found in the early 1940's, that antigenic relationships existed among certain viruses isolated in different areas of thw world. The interest of a number of scientists and of a private organization led to the establishment of an international information exchange and to the preparation of an international catalogue of arboviruses including certain other viruses of vertebrates. International cooperation was fostered by the interest taken in these agents by the World Health Organization and the creation by this agency of an international net of collaborating laboratories with assigned areas of the world. A number of recent problems have been revealed and solved, or partly solved by this international effort, among which are questions relating to: the Marburg agent disease, the existence of an antigenic relationship between rabies virus and some arboviruses, aspects of the ecology or viruses in the California, Uukuniemi and Kemerovo groups, as well as several unanticipated antigenic relationships among viruses. Numerous questions still remain the solution of which might be expedited by continued and increased cooperative international effort such as overwintering or survival of viruses under unfavorable circumstances, pathogenic potential for man and domestic animals of certain viruses, role on chronic illnesses, establishment of the etiology of certain diseases and investigations of the basic properties of viruses, particularly of the Bunyaviridae.

Isolation of chikungunya virus contaminating an Aedes albopictus cell line

An Aedes albopictus cell line was found contaminated with structures morphologically compatible with an alphavirus. Rapid isolation of a cytopathic virus was effected by combining sonication, concentration with Aquacide II-r, rate zonal sedimentation and subsequent plating of fractions on Vero cells under agar overlay. The virus caused neithedeath nor disease on inoculation into infant and adult mice. It produced a c.p.e. in Vero and BHK 21 cells, and multiplied in Singh's Aedes aegypti cells. The virus was identified serologically as chikungunya by complement-fixation and plaque reduction netralization test. Virus was not detected in a single attempt by these methods in the American Type Culture Collection A. albopicturs line. The presence of chikungunya virus in A. albopictus cells is not easily recognized and may complicate interpretation of experimental results.

Crimean hemorrhagic fever-Congo (CHF-C) virus antibodies in man, and in domestic and small mammals, in Iran

A Crimean hemorrhagic fever-Congo (CHF-C) virus antibody survey was carried out in Iran with sera from man and several animal species; this survey was done by means of agar gel diffusion precipitation (AGDP) test with the following results (percent positive of number tested): men, 13% of 351; sheep, 38% of 728; goats, 36% of 135; cattle, 18% of 130; camels, 0% of 157; small mammals, 3% of 274. A number of sera were tested by complement-fixation (CF), neutralization (N), and hemagglutination-inhibition (HI) tests in addition to the AGDP test. A good correlation was found in the results with 105 sera tested by AGDP, HI, and N, with approximately 70% to 75% positive in all three tests; by CF, only 20% were positive. Of 55 human sera, of which 15 could be tested by N test, about half were positive by AGDP and only 10% by HI at low titers; none was positive by N and CF tests. These results suggest that any one of the three serological tests (N, HI, and AGDP) can be used to survey the antibody prevalence in sera from domestic animals; the CF test, not unexpectedly, was less suitable. Our results, however, are inconclusive in regard to the human sera.

Lassa fever in Onitsha, East Central State, Nigeria in 1974

Three cases of Lassa fever occurred in Onitsha, East Central State, Nigeria, in January and February 1974. The first case was a 19-year-old Nigerian; the other 2 cases were German missionary physicians at St Charles Borromeo Hospital, Onitsha, one of whom cared for the patient who was the first case. Thus, 2 of the 3 cases were hospital acquired. Investigations failed to discover a village outbreak or the source of virus for the first case. A serosurvey of 258 hospital staff members and contacts of the 3 cases showed no other persons with antibody to Lassa virus. The absence of Lassa virus antibody in a high-risk group indicates a low or nonexistent level of past Lassa virus activity in southeastern Nigeria.

Bunyaviruses and Bunyaviridae

A new family is described, the Bunyaviridae, which contains a single genus, Bunyavirus. The main characteristics of the family are as follows: single-stranded RNA, total molecular weight about 7 X 10(6) daltons, probably in three segments. Virions spherical, enveloped particles 90-100 nm in diameter. Envelope contains at least one virus-specified glycopeptide. Develop in the cytoplasm, mature by budding into smooth-surfaced vesicles in the Golgi region or nearby. Internal ribonucleoprotein composed of long strands 2-2.5 nm broad. There are at least 150 members, 87 serologically related bunyaviruses and other probable bunyaviruses.

Diagnosis of Lassa fever and the isolation and management of patients

The clinical spectrum of Lassa fever is described and discussed in terms of the possible pathophysiological events involved. Early diagnosis is essential to permit prompt isolation of the potentially infectious patient. Lassa fever may be suspected on clinical grounds, but specific early diagnosis depends upon isolation of the virus. Virus isolation is best accomplished from serum obtained during the first 2 weeks of illness. The patterns of viraemia and virus excretion described in this paper are useful guidelines for determining the duration of patient isolation. Problems encountered in the isolation, management, and transport of the patient with Lassa fever are discussed.