Interferon Production and Host Resistance to Type II Avian (Marek''s) Leukosis Virus (JM Strain)

Interferon production in both susceptible S- and resistant K-line chickens infected with type II leukosis virus of JM strain and turkey herpesvirus was studied. The resistant line of chickens produced higher levels of interferon than did the susceptible with JM virus infection during the experimental period. When both susceptible S-and resistant K-line chicks were vaccinated with turkey herpesvirus, the interferon production was quantitatively similar in the two lines.     

Interferon Production and Host Resistance to Type II Avian (Marek's) Leukosis Virus (JM Strain)

Interferon production in both susceptible S- and resistant K-line chickens infected with type II leukosis virus of JM strain and turkey herpesvirus was studied. The resistant line of chickens produced higher levels of interferon than did the susceptible with JM virus infection during the experimental period. When both susceptible S-and resistant K-line chicks were vaccinated with turkey herpesvirus, the interferon production was quantitatively similar in the two lines.     

Characterization of Glycos-aminoglycans Associated with Rauscher Murine Leukemia Virions

Host-derived sulfated components that copurify and are physically associated with the envelope of Rauscher murine leukemia virions grown in JLS-V9 cells were characterized by digestion with chondroitinase ABC and chondroitinase AC II, as well as nitrous acid degradation. A dermatan-sulfate-chondroitin-sulfate copolymer and heparin or heparan sulfate were shown to be associated with the virions. Competitive binding studies indicated a specificity of the virions for association with heparan sulfate. The physiological importance of the association is discussed.     

Reversible Inactivation of the Deoxyribonucleic Acid Polymerase of Rauscher Leukemia Virus

Rauscher leukemia virus deoxyribonucleic acid polymerase is reversibly inactivated by 6 m guanidine-hydrochloride. Gel filtration in 6 m guanidine-hydrochloride reveals that the viral deoxyribonucleic acid polymerase consists of a single polypeptide chain of approximately 70,000 molecular weight.     

Radiation-Resistant and Radiation-Sensitive Forms of Host Resistance to Polyomavirus

Newborn mice of several inbred strains develop few or no tumors following inoculation with highly tumorigenic strains of polyomavirus. Here we show that such resistant strains can be divided into two groups based on the responses of adult mice to radiation followed by virus inoculation. Most strains show a radiation-sensitive form of resistance (R^r-s) and develop tumors following radiation and virus challenge. This type of resistance has previously been recognized as immunological, based on T-cell responses against virus-encoded neoantigen(s) expressed in tumor cells. Other strains exhibit a radiation-resistant form of resistance (R^r-r) and fail to develop tumors when treated in the same manner. Three additional properties of R^r-r mice distinguish them from R^r-s mice: (i) survival of newborns following inoculation with a highly virulent and usually lethal strain of virus, (ii) resistance to virus spread in newborns inoculated with either tumorigenic or virulent virus strains, and (iii) dominant or semidominant transmission of resistance in crosses with a highly susceptible strain. The R^r-r phenotype reflects a constitutive nonimmunological type of resistance that is targeted to the virus and blocks its dissemination.     

Interferon Induced IFIT Family Genes in Host Antiviral Defense

Secretion of interferons (IFNs) from virus-infected cells is a hallmark of host antiviral immunity and in fact, IFNs exert their antiviral activities through the induction of antiviral proteins. The IFN-induced protein with tetratricopeptide repeats (IFITs) family is among hundreds of IFN-stimulated genes. This family contains a cluster of duplicated loci. Most mammals have IFIT1, IFIT2, IFIT3 and IFIT5; however, bird, marsupial, frog and fish have only IFIT5. Regardless of species, IFIT5 is always adjacent to SLC16A12. IFIT family genes are predominantly induced by type I and type III interferons and are regulated by the pattern recognition and the JAK-STAT signaling pathway. IFIT family proteins are involved in many processes in response to viral infection. However, some viruses can escape the antiviral functions of the IFIT family by suppressing IFIT family genes expression or methylation of 5'' cap of viral molecules. In addition, the variants of IFIT family genes could significantly influence the outcome of hepatitis C virus (HCV) therapy. We believe that our current review provides a comprehensive picture for the community to understand the structure and function of IFIT family genes in response to pathogens in human, as well as in animals.     

Host Resistance in Relation to Survival in Breast Cancer

The degree of lymphocytic infiltration in and around breast tumours together with sinus histiocytosis and follicular hyperplasia in regional lymph nodes has been studied in 310 cases of breast cancer treated with standard radical mastectomy. The presence of these features was regarded as evidence of host resistance against the tumour and made possible the division of patients into three classes—no or poor reaction, good reaction, and strong reaction. The grading was shown to have a close correlation with prognosis. The relationship between host defensive factor grading and malignancy, nodal metastases, and survival was also examined. The results support the hypothesis that prognosis in breast cancer is closely related to a histological picture of cell-mediated immunity against the tumour.     

Purification of the Moloney and Rauscher Murine Leukemia Viruses by Use of Zonal Ultracentrifuge Systems

The B-IV and B-IX zonal ultracentrifuge rotors were applied to the concentration and purification of the Moloney and Rauscher murine leukemia viruses from large volumes of infected tissue culture fluids and animal materials. Potassium tartrate, potassium citrate and sucrose gradients were used to obtain viral concentrates from the density 1.16 to 1.18 zone. Proteolytic enzyme digestion of tissue culture preparations prior to zonal ultracentrifuge processing was effective in releasing virus from cell debris and producing highly purified, though nonleukemogenic, viral concentrates. Infected Rauscher mouse plasma was processed to give highly purified infectious virus fractions. A single centrifugation of crude Rauscher mouse spleen homogenates resulted in partially purified infectious concentrates with high virus particle counts.     

Stimulation of Nonspecific Host Resistance to Infection Induced by Muramyldipeptides

The effect of muramyldipeptide (MDP), N-acetylmuramyl-l-alanyl-d-isoglutamine [MDP(Ala)], and its analogs on bacterial infection was studied using the experimental model of sepsis infection in mice. Injection of MDP(Ala) gave mice definitive protection against E. coli infection, but only partial protection against P. aeruginosa or K. pneumoniae infection. Several factors influencing the protective activity of MDP (Ala) on E. coli infection were studied, and it was demonstrated that the activity was induced by various routes of administration of MDP(Ala), including the oral route, and was markedly influenced by the bacterial inoculum size. It was also shown that the effective dose of MDP(Ala) was 100 μg per mouse for intraperitoneal, intravenous or subcutaneous injections and 1,000 μg per mouse when administered orally. Furthermore, the optimal interval between MDP-treatment and infection was 24 hr when the treatment was carried out before infection. Clearance of bacterial cells in blood was observed after E. coli infection in mice treated with MDP(Ala). The efficacy of MDP(Ala) and two analogs, N-acetylmuramyl-l-valyl-d-isoglutamine [MDP(Val)] and N-acetylmuramyl-l-seryl-d-isoglutamine [MDP (Ser)], was evaluated for the E. coli infection; MDP(Val) was proven to be slightly less active than MDP(Ala), and MDP(Ser) to be the least effective, although MDP(Val) or MDP(Ser) was reported to have higher adjuvanticity than MDP (Ala) for the development of delayed-type hypersensitivity.     

Interferon Regulatory Factor 6 Has a Protective Role in the Host Response to Endotoxic Shock

Interferon Regulatory Factor (IRF) 6, a member of the IRF family, is essential for epidermal and orofacial embryonic development. Irf6 is strongly expressed in keratinocytes, in which it regulates epidermal proliferation, differentiation, and migration. A recent role for Irf6 in Toll-like receptor 2-dependent chemokine gene expression was also reported in an epithelial cell line. However, a function for Irf6 in innate immune cells was not previously reported. In the present study, we investigated the expression and function of Irf6 in bone marrow-derived neutrophils and macrophages. We show here, using a conditional knockout of Irf6 in lysosymeM expressing cells, that Irf6 is required for resistance to LPS-induced endotoxic shock. In addition, Irf6-deficient bone marrow-derived neutrophils exhibited increased chemotactic index and velocity compared with wild-type cells in vitro. TLR4-specific KC and IL6 secretions were upregulated in Irf6-deficient bone marrow-derived macrophages in vitro. These cells also exhibited an increased level of phosphorylated IkBa. Collectively, our findings suggest a role for Irf6 in the resistance to endotoxic shock due to NFk-B-mediated alteration of cytokine production.