The susceptibility of pregnant mice to encephalomyocarditis (EMC) virus infection on different days of gestation.

Pregnant mice of the BALB/c CrSlc strain were experimentally infected with the D variant of encephalomyocarditis virus (EMC-D, 5 x 10(2) PFU/head) on three different gestational days (GD). Mice were intraperitoneally inoculated with EMC-D on 11, 13 and 15 GD and sacrificed 3 days post inoculation. There was no significant difference in the fetal mortality among all inoculation groups. Placenta showed higher virus titer than fetus and dam's serum in all inoculation groups, and the virus titer of the fetus was lowest in the 15GD group. Histopathological changes and signals of viral RNAs detected by in situ hybridization were observed almost restricted to the spongiotrophoblast layer of the placenta in all inoculation groups, and the signals were strongest in the 11GD group. In the fetus of the11GD group, signals of viral RNAs were also seen in myocardium and hepatocytes. Ultrastructurally, intracytoplasmic aggregations of virus-like particles in crystalline array were observed in trophoblast cells and giant cells in the spongiotrophoblast layer in all inoculation groups.     

Cardiac and pancreatic lesions in guinea pigs infected with encephalomyocarditis (EMC) virus.

Cardiac and pancreatic lesions were observed in guinea pigs infected with 2 variants (B and D) of encephalomyocarditis (EMC) virus. Cardiac changes were characterized by focal myocardial necrosis and subsequent replacement by immature granulation tissue, and the pancreatic ones by vacuolar degeneration of acinar cells. In the electron microscopic examinations, the affected cardiomyocytes showed intracellular oedema, swelling and/or partial destruction of mitochondria, and distortion and disruption of myofibrils. Intracellular vacuolization and dilatation of rough-surfaced endoplasmic reticulum (rER) were conspicuous in the damaged pancreatic acinar cells. In addition, intracisternal granules were found in dilated rER with a high frequency. These changes were common to animals infected with the B and D variants. On the contrary, B cell alterations; i.e. degranulation and degeneration of insulin granules, were detected only in animals infected with the D variant.     

Replication of diabetogenic and nondiabetogenic variants of encephalomyocarditis (EMC) virus in ICR Swiss mice

The replication of the diabetogenic D (EMC-D) and nondiabetogenic B (EMC-B) variants of encephalomyocarditis virus in various tissues of the murine host was determined. Pancreatic insulin levels were also measured. EMC-D replicated in the spleen, pancreas, heart, lung, and intestines, while EMC-B was limited to the spleen and pancreas. EMC-B interfered with the replication of EMC-D in each of the tissues examined. Insulin levels were initially increased by both viruses. By 4 days postinfection, insulin levels were either normal or undetectable in (EMC-D)-infected animals, but were dramatically elevated in those infected with EMC-B.     

Susceptibility of some weed species to Pepino mosaic virus (PepMV)

The aim of our investigations was to study the susceptibility of 22 weed species to Pepino mosaic virus (PepMV). Seven plants of each species were mechanically inoculated at 4-6 leaf stage with PepMV in a vector free virological glasshouse. Inoculated plants were tested on the basis of symptoms, by DAS ELISA serological method and back inoculation. Among the 22 weed species, only some Solanum ones (S. aethiopicum, S. dulcamara, S. luteum, S. nigrum) were susceptible to PepMV infection. All of them--except S. aethiopicum--belong to Hungarian weed flora, therefore these weeds--occurring mainly in tomato ecosystems--may play important role in the epidemiology of PepMV. Other 18 weed species seemed to be resistant to PepMV, and on the basis of back inoculation not even latent infection has been observed.     

Effect of rearing conditions on encephalomyocarditis (EMC) virus-induced diabetes in mice

To compare the incidence in the diabetic syndrome in mice reared under sterile and non-sterile conditions, both conventional and SPF DBA/2 N male mice were inoculated intraperitoneally with two doses (10(4) TCID50/0.1 ml or 10(5) TCID50/0.1 ml) of encephalomyocarditis (EMC) virus M variant. The incidence of diabetic symptoms was higher in mice reared under sterile conditions than under non-sterile conditions. It appeared that a difference in animal rearing conditions would affect the sensitivity to EMC virus in mice.     

Susceptibility of some Lycopersicon species and varieties to cucumber mosaic virus (CMV) and tobacco mosaic virus (TMV)

Susceptibility of 33 Lycopersicon species and varieties to Tobacco mosaic virus (TMV) and Cucumber mosaic virus (CMV) were studied. Plants were mechanically inoculated with the C/U1 strain of TMV and U/246 strain of CMV. Virus infection was checked by symptomatology, DAS ELISA and back inoculation (biotest). All the studied Lycopersicon species and varieties were susceptible to TMV-C/U1. L. esculentum Mill. convar. infiniens Lehm. var. flammatum Lehm., L. esculentum Mill. convar. fruticosum Lehm. var. speciosum Lehm. and L. esculentum Mill. convar. infiniens Lehm. var. validum Bail. showed extreme resistance to CMV-U/246. The other 30 species and varieties were susceptible to CMV-U/246. New compatible and incompatible host-virus relations have been reported. The extreme resistant Lycopersicon varieties could be used as resistance sources in tomato breeding.     

Induction of 2',5' oligo(A) synthetase in tumor-bearing mice with encephalomyocarditis (EMC) virus or poly(I)poly(C)

Infection of 13 month-old C3H mice with EMC virus or inoculation with the interferon inducer poly(I)poly(C) results in elevated levels of the enzyme 2',5' oligo(A) synthetase only in animals with spontaneous tumors (breast cancer or hepatomas). High enzymatic activities are detected in homogenates from liver, spleen, plasma and neoplastic cells of the animals with breast carcinomas and only in the neoplastic liver cells of the animals with hepatomas.     

Susceptibility of four species of turfgrass-infesting scarabs (Coleoptera: Scarabaeidae) to Bacillus thuringiensis serovar japonensis strain Buibui

Bacillus thuringiensis serovar japonensis strain Buibui experimental formulations containing Cry8Cal delta-endotoxin were evaluated in the field for the control of oriental beetle, Anomala orientalis Waterhouse; Japanese beetle, Popillia japonica Newman; Asiatic garden beetle, Maladera castanea (Arrow); and European chafer, Rhizotrogus majalis (Razoumowsky) larvae infesting turfgrasses. In 17 fall applications, control of A. orientalis and P. japonica was achieved at rates as low as 100 g of toxin per ha; however, rates of 301 or 593 g/ha were consistently more effective. A. orientalis larvae were the most susceptible followed by P. japonica, R. majalis, and M. castanea. Two spring applications of 120 g of toxin per ha were not effective against oriental or Japanese beetles.     

CD1d mediates T-cell-dependent resistance to secondary infection with encephalomyocarditis virus (EMCV) in vitro and immune response to EMCV infection in vivo

The innate and adaptive immune responses have evolved distinct strategies for controlling different viral pathogens. Encephalomyocarditis virus (EMCV) is a picornavirus that can cause paralysis, diabetes, and myocarditis within days of infection. The optimal innate immune response against EMCV in vivo requires CD1d. Interaction of antigen-presenting cell CD1d with distinct natural killer T-cell ("NKT") populations can induce rapid gamma interferon (IFN-gamma) production and NK-cell activation. The T-cell response of CD1d-deficient mice (lacking all NKT cells) against acute EMCV infection was further studied in vitro and in vivo. EMCV persisted at higher levels in CD1d-knockout (KO) splenocyte cultures infected in vitro. Furthermore, optimal resistance to repeat cycles of EMCV infection in vitro was also shown to depend on CD1d. However, this was not reflected in the relative levels of NK-cell activation but rather by the responses of both CD4(+) and CD8(+) T-cell populations. Repeated EMCV infection in vitro induced less IFN-gamma and alpha interferon (IFN-alpha) from CD1d-deficient splenocytes than with the wild type. Furthermore, the level of EMCV replication in wild-type splenocytes was markedly and specifically increased by addition of blocking anti-CD1d antibody. Depletion experiments demonstrated that dendritic cells contributed less than the combination of NK and NKT cells to anti-EMCV responses and that none of these cell types was the main source of IFN-alpha. Finally, EMCV infection in vivo produced higher levels of viremia in CD1d-KO mice than in wild-type animals, coupled with significantly less lymphocyte activation and IFN-alpha production. These results point to the existence of a previously unrecognized mechanism of rapid CD1d-dependent stimulation of the antiviral adaptive cellular immune response.     

Susceptibility of two turtle species to eastern equine encephalitis virus

Two species of turtle collected in southern New England were inoculated subcutaneously with eastern equine encephalitis virus. The spotted turtles (Clemmys guttata) developed viremia and neutralizing antibody after exposure to 3 logs or more of virus. Viremia was not detected in the eastern painted turtles (Chrysemys picta), and neutralizing antibody was detected in only 1 of 15 inoculated C. picta; however, since pre-inoculation serum was not obtained from this animal, the possibility of natural infection cannot be eliminated.