Reassortant virus derived from avian and human influenza A viruses is attenuated and immunogenic in monkeys.

An influenza A reassortant virus that contained the hemagglutinin and neuraminidase genes of a virulent human virus, A/Udorn/72 (H3N2), and the six other influenza A virus genome segments from an avirulent avian virus, A/Mallard/New York/6750/78 (H2N2), was evaluated for its level of replication is squirrel monkeys and hamsters. In monkeys, the reassortant virus was as attenuated and as restricted in its level of replication in the upper and lower respiratory tract as its avian influenza virus parent. Nonetheless, infection with the reassortant induced significant resistant to challenge with virulent human influenza virus. In hamsters, the reassortant virus replicated to a level intermediate between that of its parents. These findings suggest that the nonsurface antigen genes of the avian parental virus are the primary determinants of restriction of replication of the reassortant virus in monkeys. Attenuation of the reassortant virus for primates is achieved by inefficient functioning of the avian influenza genes in primate cells, while antigenic specificity of the human influenza virus is provided by the neuraminidase and hemagglutinin genes derived from the human virus. This approach could lead to the development of a live influenza A virus vaccine that is attenuated for man if the avian influenza genes are similarly restricted in human cells.

Transfer factor.

A workshop on transfer factor, sponsored by the Immunology, Allergic and Immunologic Diseases Program of the National Institute of Allergy and Infectious Diseases, National Institutes of Health, was held in Bethesda, Maryland, on February 25, 1981. The purpose of the meeting was two-fold: (1) to review the state of the art of transfer factor and (2) to suggest future directions for research in this area, specifically in regard to the prophylactic use of transfer factor for varicella-zoster in leukemic children.

Epidemiologic and socioeconomic aspects of allergic diseases.

It is evident that asthma and the other allergic diseases constitute a health problem of international scope. There is a need for well-designed, large-scale, prospective epidemiologic studies designed to define precisely the magnitude of the worldwide problem created by allergic disorders. Most studies to date have been small and have involved special groups rather than the entire population. With the exception of data reported from developing countries, prevalence rates for childhood asthma are noted to be both increasing and higher than adult rates. While exact reasons are not known, the state of development of immune system regulation and hyperreactivity to allergens encountered in early life may play a role. Whether the actual prevalence and incidence of allergic diseases in children are increasing or whether this observation represents a phenomenon resulting from improved diagnostic methods and recognition of these disorders needs to be established. Paradoxically, despite advances in treatment, the severity of asthma and allergic diseases appears to be increasing. Accordingly, it is especially important to search for the factors that lead to the expression of immune and hypersensitivity mechanisms. Differences in rural and urban populations appear to be real and suggest the need to examine the factors of indoor and outdoor environments created by air pollution, crowding, and allergen exposure and the demands made on the immune system by frequency of challenge by respiratory tract infections. Still among the unknowns is the effect on the natural history of allergic disease after changes in urban-rural residences in countries in which helminth infections are not hyper IgE-stimulating factors. The creation of new occupationally related allergens at worksites and the contribution of industrialization to the deterioration of the natural environment needs to be adequately assessed. Whether breast feeding may have an effect on either the prevention or delayed emergence of food allergies in children requires documentation by long-term prospective studies based on objective testing. A possible relationship between respiratory tract infection and the development of asthma is exemplified by clinical observations. The emergence of asthma in infants increases with successive episodes of bronchiolitis; triggering of asthmatic attacks by acute respiratory tract viral infections is a common occurrence, especially during childhood years; and chronic adult onset asthma is often preceded or accompanied by chronic sinusitis or complicated by lower respiratory tract infection.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell line derived from a murine sarcoma virus (Moloney Pseudotype)-induced tumor: cultural, antigenic, and virological properties.

A cell line derived from a murine sarcoma virus (Moloney pseudotype)-induced tumor has been established. It retains oncogenicity, releases both sarcoma and leukemia viruses, and has virus-induced cellular antigens.

The atopic dog model: report of an attempt to establish a colony.

In an attempt to establish a colony of atopic dogs as a research resource, dogs with seasonal dermatitis - a reported manifestation of naturally occurring allergy in that species - were identified, acquired, and inbred. Progeny were studied during their first 2 years of life to determine if the trait could be genetically transmitted and to investigate the hypothesis that this spontaneously occurring dermatitis correlates with positive laboratory measurements for specific IgE to airborne allergens. (Serial immunoglobulin levels, including total IgE, end-point titration of histamine, and results of fecal examinations for identification of parasites were also investigated and are to be the subject of a separate publication.) Only a weak correlation between positive direct skin test results and the appearance of seasonal dermatitis was found in initial studies. Neither the results of testing by passive cutaneous anaphylaxis nor radioallergosorbent procedures correlated with positive clinical findings. Independently conducted clinical examinations and direct skin testing using selected antigens, as well as additional bronchial challenges of representative animals from the colony, also failed to furnish evidence of atopy in the dogs. Therefore, the goal of establishing an inbred line of atopic animals was not accomplished within the allotted 2-year period. Also, the data did not show a positive correlation between the seasonal dermatitis and measurements for specific IgE to airborne allergens.

Cell and tissue distribution of 14C-labeled pyran copolymer.

The tissue distribution of pyran (maleic anhydride-divinyl ether) copolymer was studied after a single ip injection of 14C-labeled pyran (25 mg/kg) to mice. The pyran showed a reticuloendothelial distribution with the liver and spleen containing the highest concentrations which persisted for at least 21 days after drug treatment. Blood levels of 14C-pyran reached a peak 2 hours after injection and were cleared within 6 hours. Attempts to measure uptake of 14C-pyran by peritoneal macrophages were unsuccessful due to an inability to recover macrophages between 3 and 24 hours after ip pyran administration. Since activated macrophages appear to be the primary mechanism by which pyran enhances host resistance to microbial infection and neoplasia, the uptake of 14C-pyran by isolated peritoneal macrophages in vitro was studied. Purified macrophages showed a gradually increasing uptake of 14C-pyran, and a large amount of cell-associated radioactivity was bound to trichloroacetic acid-precipitable material. Several polyanions, including unlabeled pyran, dextran sulfate, and poly(I)-poly(C), competed for acid-precipitable receptor molecules. The superior antitumor effects of pyran as compared to other polyanions may result from the continuous presence of the synthetic polymer in the host. Possible mechanisms of immunopotentiation by pyran are discussed.

Temperature-sensitive mutants of influenza A virus. Transfer of the two ts-1A2 ts lesions present in the Udorn/72-ts-1A2 donor virus to the influenza A/Alaska/6/77 (H3N2) wild type virus.

The Udorn/72-ts-1A2 temperature-sensitive influenza A virus has a 37 degrees C shutoff temperature and a ts mutation on the genes coding for the P1 and P3 proteins. This ts donor virus was produced with the expectation that the transfer of its two ts genes would regularly and predictably attenuate each new variant of influenza A virus. It had previously been mated with the A/Victoria/75 (H3N2) virus and five Vic/75-ts-1A2 rcombinants were isolated that had both ts-1A2 ts genes and in vitro and in vivo genetic and biological properties similar to their Udorn/72-ts-1A2 parent. The present study was designed to determine if the acquisition of the two ts-1A2 ts genes would also confer a specific level of attenuation on the influenza A/Alaska/6/77 (H3N2) wild type virus. Fifteen recombinant Alaska/77-ts-1A2 viruses were isolated and characterized genetically for the number and location of ts mutations. These clones were also studied for their level of replication and genetic stability in hamsters. Four recombinants possessed both of the ts-1A2 mutations and had a 37 degrees C shutoff temperature for plaque formation. Two recombinants possessed only a ts P1 gene and had either a 38 degrees C or 39 degrees C shutoff temperature. The remaining nine clones had the ts P3 gene and a shutoff temperature of 37 degrees C, 38 degrees C or 39 degrees C. Each of the four 37 degrees C shutoff temperature recombinants that possessed both ts P1 and P3 genes were restricted at least 10,000-fold in replication in the hamster's lung and approximately 100-fold in the nasal turbinates compared to the level of replication of wild type virus in these sites. All isolates from these animals retained the ts phenotype. The level of replication in vivo of the ts P1 and P3 segregants was related to their shutoff temperature of plaque formation in vitro, e.g. the 38 degrees C ts P3 segregant was less restricted in replication in the lungs than a 37 degrees C ts P3 segregant. All isolates from animals infected with the ts P3 segregants were ts, whereas a low level of genetic instability was detected for one of the ts P1 segregants. Since ten independent ts-1A2 recombinants (one Udorn/72, 5 Victoria/75 and 4 Alaska/77) with both ts-1A2 mutations exhibited the same genetic and biologic properties, it is likely that these ts P1 and P3 genes were the prime determinants of attenuation and could effect a similar level of attenuation in other influenza A viruses within the H3N2 subtype.

Effect of chemically modified 70S RNA from avian myeloblastosis virus (AMV) upon the activity of AMV DNA polymerase.

Adenine residues of 70S avian myeloblastosis virus (AMV) RNA are modified when reacted with chloroacetaldehyde. This modification introduces characteristic fluorescent epsilon-adenosine (epsilonA) probes which were used to monitor the reaction. Under suitable conditions, modified 70S(epsilonA) RNA was maintained intact and was inactive as a template for the AMV DNA polymerase. Furthermore, it inhibited the reaction catalyzed by AMV polymerase when 70S RNA was used as template-primer and had no effect on the two tested bacterial polymerases. Protection against the 70S (epsilonA) RNA inhibition was observed when 70S RNA was primed with oligo(dT) indicating preference of the polymerase for the oligo(dT) primed regions.

Production and level of genetic stability of an influenza A virus temperature-sensitive mutant containing two genes with ts mutations.

Temperature-sensitive (ts) reassortant vaccine strains derived from the A/Udorn/72 ts-1A2 donor virus were not sufficiently stable genetically in humans. We therefore sought to produce a new, more stable donor virus. We had previously identified a stable ts virus with a ts P3 gene and in the current study identified another relatively stable single-lesion ts virus with a ts mutation in the NP gene. A new ts reassortant virus was constructed by mating these two single mutants and by isolating three reassortant progeny, clones 20, 53, and 55, that contained both a ts P3 and a ts NP gene. These reassortant progeny possessed a 37 to 38 degrees C shutoff temperature and were as restricted in their replication in hamster lungs as the A/Udorn/72 ts-1A2 virus. All isolates from the lungs and nasal turbinates of hamsters were temperature sensitive. An in vitro stress test was used to determine whether the new ts P3 ts NP reassortant virus would undergo loss of its ts phenotype after replication at semipermissive temperature. Clone 20 and 55 reassortants underwent progressive loss of their ts phenotype in vitro, although at a rate slightly less than that of the A/Udorn/72 ts-1A2 virus. The level of genetic stability after replication in vivo was assessed in cyclophosphamide-treated hamsters in which virus replication continued for up to 15 days. Again, both the A/Udorn/72 ts-1A2 and the new ts P3 ts NP reassortant clone 55 manifested a progressive loss of temperature sensitivity after 7 days of replication. Clone 55 virus lost temperature sensitivity significantly less rapidly than the A/Udorn/72 ts-1A2 virus. These results indicated that, although the new ts P3 ts NP reassortant virus was more stable than the A/Udorn/72 ts-1A2 virus, it nevertheless underwent progressive loss of temperature sensitivity after replication in vitro and in vivo. Therefore, it does not appear to be a satisfactory donor virus. This experience plus that gained earlier with other ts mutants of influenza A virus suggest that influenza A virus mutants that rely solely upon their ts phenotype for attenuation are unlikely to exhibit the phenotypic stability required of a vaccine virus. Other genetic techniques are needed to produce more stable influenza A virus strains.