The spread of Rift Valley fever and approaches to its control.

Rift Valley fever (RVF) is primarily a disease of sheep, cattle, other domestic animals, and man; it was believed to be relatively benign for man until 1977 when it spread to Egypt. There it caused enormous losses of sheep and cattle, and thousands of human cases occurred, with nearly 600 reported deaths. Although mosquitos are known to transmit RVF virus in epizootics and epidemics, the reservoir and means of inter-epizootic maintenance are not known.

A serological survey of Rift Valley fever antibodies in the northern Sinai.

In the aftermath of an extensive Egyptian Rift Valley fever (RVF) epidemic during 1977-78, RVF activity in the adjacent Sinai peninsula has been inferred from the presence of haemagglutination-inhibition (HI) antibodies in sera from indigenous humans and rodents. We attempted to confirm these findings by HI testing of sera from Israeli soldiers serving in the region of the El Arish Wadi system in the Sinai, and from indigenous rodents. Six of 199 human sera (3.

Formation and characterization of an intertypic lymphocytic choriomeningitis recombinant virus.

An intertypic reassortant arenavirus has been obtained from co-infection of BHK-21 cells by two strains of lymphocytic choriomeningitis virus (LCM virus), WE and Armstrong (ARM), having the large/small (L/S) viral RNA genotype of WE/ARM. The two parental viruses have different virulence characteristics in hamsters and guniea-pigs. The reassortant virus induces LCM-WE-type plaques in Vero cell monolayers, but has the avirulent characteristics of LCM-ARM in hamsters and two strains of guniea-pigs.

Glucan-induced enhancement of host resistance to selected infectious diseases.

We conducted studies with mice, rats, and monkeys which demonstrated the ability of glucan to induce either nonspecific or specific enhancement of host resistance to infectious diseases. Intravenous pretreatment of mice with glucan significantly enhanced the survival of mice challenged with either Venezuelan equine encephalomyelitis (VEE) virus or Rift Valley fever virus. Pretreatment was beneficial when initiated 3 days before challenge with VEE virus and 7 days before challenge with Rift Valley fever virus.

Evaluation of a formalin-inactivated Rift Valley fever vaccine in sheep.

A formalin-inactivated Rift Valley fever (RVF) vaccine prepared in cell culture for human use was immunogenic in sheep. Vaccine was administered as a single dose of diluted (1:5) or undiluted vaccine with or without an adjuvant. Serum-neutralizing antibodies induced by RVF vaccine persisted for at least 7 months.

Male determined accelerated autoimmune disease in BXSB mice: transfer by bone marrow and spleen cells.

Autoimmune disease in BXSB mice progresses more rapidly in male animals. We have investigated the cellular basis of this effect by transferring male and female bone marrow and spleen cells into male and female lethally irradiated BXSB recipients. The rate of development of disease was measured by the overall mortality rate, mortality from glomerulonephritis, and development of serologic abnormalities.

Adjuvant activity of a novel metabolizable lipid emulsion with inactivated viral vaccines.

Studies were conducted in mice, hamsters, sheep, and two species of nonhuman primates which demonstrate the adjuvant activity of a new metabolizable lipid emulsion with marginally immunogenic doses of Formalin-inactivated viral vaccines. The lipid base consists of highly refined peanut oil emulsified in aqueous vaccines with glycerol and lecithin. Hamsters and mice inoculated with lipid emulsion plus western or Venezuelan equine encephalitis vaccine were significantly more resistant than vaccinated controls to lethal homologous virus challenge.

Baroreflex sensitivity in rabbits during the development of experimental renal hypertension and medial sclerosis.

Baroreflex sensitivity was assessed in 9 normotensive (N), 8 renal wrap (one kidney model, RH) and 16 medial sclerotic rabbits (MS, fed on calciferol 50,000 i.u. and calcium lactate 1g for 10 days) before (mean BP;N, 79 +/- 3.

Natural thymocytotoxic autoantibodies in autoimmune and normal mice.

Natural thymocytotoxic autoantibodies (NTA) were found in all mouse strains. Among those strains that show autoimmune syndromes resembling human systemic lupus erythematosus (SLE), the NZB and NZBxNZW had high levels of NTA, the BXSB had moderate levels, and the MRL/1 and MRL/n had very low levels. In addition, some normal strains had high levels, sometimes even higher than the autoimmune strains.

Differential effects of propranolol on lymphocyte rosette formation and response to plant mitogens.

The effects of propranolol on various lymphocyte functions were studied to gain a better understanding of the recently demonstrated suppressive effect of propranolol on rheumatoid factor production. D- and L-propranolol at a concentration of 1 X 10(-4)M inhibited the formation of human EA rosettes. The inhibition occurred within one minute of adding the compounds, was reversible, and did not affect cell viability.

Replication of dengue and junin viruses in cultured rabbit and human endothelial cells.

The flavivirus dengue and the arenavirus Junin are both associated with a hemorrhagic shock syndrome in man. We have demonstrated the replication of these viruses in vitro in both rabbit and human endothelial cells by viral titers and immunofluorescent antibody studies. Rabbit endothelium established in continuous culture was derived from vena cava, while human cells in primary culture were derived from umbilical veins.

Antibody-dependent cellular cytotoxicity against murine leukemia viral antigens: studies with human lymphoblastoid cell lines and human peripheral lymphocytes as effector cells comparing rabbit, goat, and mouse antisera.

A thymic lymphoblastoid cell line derived from a New Zealand Black mouse produces murine leukemia virus (MuLV) and was used as a target in model systems for the in vitro study of antibody-dependent cellular cytotoxicity (ADCC). Several human lymphoblastoid cell lines were investigated as potential effector cells. The most promising (Raji cells) bound to antibody-coated target cells but caused only modest levels of ADCC at 25:1 effector-to-target cell ratio with substantial lysis in the absence of antiserum.

Radioimmunoassay for antibody to hepatitis B surface antigen shows transmission of hepatitis B virus among household contacts.

The epidemiology of infections with hepatitis B virus was studied by measurement of serum antibodies to hepatitis B surface antigen (HBS Ag) with the radioimmuno-precipitation test. Prospective studies of household contacts of HBS Ag-positive patients with acute hepatitis demonstrated that four of 41 children and one of 60 adults experienced anicteric seroconversions. Two of the 60 adults also had mild icteric hepatitis and became chronically antigenemic.

The seroepidemiology of reovirus, coxsackievirus infections among Panamanian Indian children.

Rates of hepatitis B virus infection varied significantly among Panamanian Indian tribes. Chocó and Mainland Cuna Indians had a greater prevalence of antibody to hepatitis B surface antigen than Guaymi and Island Cuna Indians. The village water supply appeared to be the major environmental difference that distinguished the tribes from one another.

IgM levels and IgM-mediated immune responses in patients with acute hepatitis A, acute hepatitis B and chronic HB antigenaemia.

Immunoglobulin M (IgM) levels and their relationship to isohaemagglutinins, febrile agglutinins, sheep cell agglutinins, and rheumatoid factor were measured in patients with acute hepatitis A, acute hepatitis B, chronic hepatitis B antigenaemia, and normal control populations. Significant IgM elevations were observed in both types of acute hepatitis, but not in chronic hepatitis B antigenaemia. There was no correlation of the IgM level with either the prevalence or titre of any IgM-mediated immune response studied.

The epidemiology of hepatitis B antigen and antibody among Panamanian Cuna Indians.

Previous studies of hepatitis B antigen (HBsAg) and antibody to it (anti-HBs) showed widely differing exposures between Panamanian Indian tribes. Cuna Indians living on islands appeared infrequently exposed to HBsAg; we found no one antigenemic and low age specific anti-HBs rates. In contrast, mainland dwelling Guaymi and Chocó Indians had a high prevalence of anti-HBs.

Familial clustering of hepatitis B surface antigen among Panamanian Indians.

Several authors have suggested that the host genome determines the occurrence of chronic HBS Ag (hepatitis B surface antigen). In attempts to evaluate this possibility, total infection rate and the combined frequencies of HBS Ag and antibody to HBS Ag and radioimmunoprecipitation to measure antibody to HBS Ag, we tested sera from 255 Panamanian Guaymi Indians. They represented 48 families and 32 living units.