Do cells treated with human interferon survive virus infection?

Abstract HeLa cells pretreated with human lympho-blastoid interferon (Hu IFN-α (Ly)), at concentrations up to 100 IU / ml and infected with moderate multiplicities of encephalomyocarditis (EMC) virus (10 PFU / cell) died 1 or 2 days after infection. However, if cells were repeatedly treated with high doses of IFN (800 IU / ml) they survived infection by EMC virus for at least a month. Cells survived Semliki Forest virus (SFV) infection when even lower IFN concentrations were used. By contrast infection of IFN-treated HeLa cells with other RNA-containing viruses, such as poliovirus, vesicular stomatitis virus (VSV), Newcastle disease virus (NDV) and reovirus type 3 resulted in cell death. Similarly, infection with a number of DNA-containing viruses such as adenovirus type 5, Herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) and vaccinia virus killed cells. The results are discussed in the light of different models for the molecular mechanism of action of interferon.     

Induction of Specific Chromosomal Aberrations by Adenovirus Type 12 in Human Embryonic Kidney Cells

Nonrandom chromosomal breaks in chromosomes 1 and 17 were provoked in human embryonic kidney cells 24 hr after infection with adenovirus type 12. These chromosomal changes disappeared in persistently infected cultures. Neutralization of the virus with type-specific antiviral serum prior to infection prevented the occurrence of chromosomal aberrations. No viral deoxyribonucleic acid (DNA) synthesis, as determined by autoradiography, was seen in metaphases containing adenovirus type 12-induced chromosomal aberrations. Ultraviolet irradiation of the virus reduced chromosomal aberrations linearly. This reduction in aberrations was fourfold slower than the inactivation of viral infectivity. At 24 hr after infection of cells with purified (3)H-labeled adenovirus type 12, the isotope was found to be associated with the nuclei. The uptake of isotope was reduced ninefold when the labeled virus was neutralized with type-specific antiviral serum. This difference is considered to account for neutralization of labeled virions. In metaphases infected with labeled viruses, most of the clustered grains were seen only on one arm of the chromatid, even after 72 hr. Isochromatid labeling was found, however, in a small percentage of chromosomes, and increased with time after infection. This increase was threefold between 24 and 72 hr after infection, whereas the mean grain counts decreased twofold during the same period. This has been tentatively interpreted to mean that most of the viral DNA molecules or parts thereof are merely attached to cellular chromatin, but a small fraction of them becomes gradually integrated as time proceeds. Certain chromosomal sites appeared to be preferentially labeled when chromosome 2 was used as a model for evaluation.     

Mechanism of Inhibition of Vaccinia Virus Replication in Adenovirus-Infected HeLa Cells

The ability of vaccinia virus to replicate in HeLa cells which had been previously infected with adenovirus type 2 (Ad2) was studied in order to gain insight into the mechanism by which adenovirus inhibits the expression of host cell functions. Vaccinia virus was employed in these studies because it replicates in the cytoplasm, whereas Ad2 replicates in the nucleus of the cell. It was found that vaccinia deoxyribonucleic acid (DNA) synthesis is greatly inhibited in adeno-preinfected HeLa cells provided that vaccinia superinfection does not occur before 18 hr after adeno infection. The inhibition of vaccinia DNA synthesis can be traced to an inhibition of vaccinia protein synthesis and viral uncoating. Vaccinia ribonucleic acid (RNA) synthesis is not inhibited in adeno-preinfected cells, but the vaccinia RNA does not become associated with polysomes.     

Therapy and long-term prophylaxis of vaccinia virus respiratory infections in mice with an adenovirus-vectored interferon alpha (mDEF201)

An adenovirus 5 vector encoding for mouse interferon alpha, subtype 5 (mDEF201) was evaluated for efficacy against lethal vaccinia virus (WR strain) respiratory infections in mice. mDEF201 was administered as a single intranasal treatment either prophylactically or therapeutically at doses of 10(6) to 10(8) plaque forming units/mouse. When the prophylactic treatment was given at 56 days prior to infection, it protected 90% of animals from death (100% protection for treatments given between 1-49 days pre-infection), with minimal weight loss occurring during infection. Surviving animals re-challenged with virus 22 days after the primary infection were protected from death, indicating that mDEF201 did not compromise the immune response against the initial infection. Post-exposure therapy was given between 6-24 h after vaccinia virus exposure and protection was afforded by a 10(8) dose of mDEF201 given at 24 h, whereas a 10(7) dose was effective up to 12 h. Comparisons were made of the ability of mDEF201, given either 28 or 1 day prior to infection, to inhibit tissue virus titers and lung infection parameters. Lung, liver, and spleen virus titers were inhibited to nearly the same extent by either treatment, as were lung weights and lung hemorrhage scores (indicators of pneumonitis). Lung virus titers were significantly (>100-fold) lower than in the placebo group, and the other infection parameters in mDEF201 treated mice were nearly at baseline. In contrast, viral titers and lung infection parameters were high in the placebo group on day 5 of the infection. These results demonstrate the long-acting prophylactic and treatment capacity of mDEF201 to combat vaccinia virus infections.     

Partial antiviral activities of the Asn631 chicken Mx against newcastle disease virus and vesicular stomatitis virus

Conflicting data existed for the antiviral potential of the chicken Mx protein and the importance of the Asn631 polymorphism in determination of the antiviral activity. In this study we modified the chicken Mx cDNA from the Ser631 to Asn631 genotype and transfected them into COS-I cells, chicken embryonic fibroblast (CEF) or NIH 3T3 cells. The Mx protein was mainly located at the cytoplasm. The transfected cell cultures were challenged with newcastle disease virus (NDV) or vesicular stomatitis virus (VSV), cytopathic affect (CPE) inhibition assay showed that the times for development of visible and full CPE were significantly postponed by the Asn631 cDNA transfection at 48 h transfection, but not by the Ser631 cDNA transfection. Viral titration assay showed that the virus titers were significantly reduced before 72 h postinfection. CEF cells was incubated by the cell lysates extracted from the COS-I cells transfected with pcDNA-Mx/Asn631, could resist and delayed NDV infection. These data suggested the importance of the Asn631 polymorphism of the chicken Mx in determination of the antiviral activities against NDV and VSV at early stage of viral infection, which were relatively weak and not sufficient to inhibit the viral replication at late stage of viral infection.     

Selection of Temperature-Sensitive Mutants During Persistent Infection: Role in Maintenance of Persistent Newcastle Disease Virus Infections of L Cells

Virus mutants (NDV(pi)) recovered from L cells persistently infected with Newcastle disease virus (NDV, Herts strain) are temperature-sensitive (ts) at 43 C, although the wild-type virus (NDV(o)) which initiated the persistent infection replicates normally at that temperature. To study the relationship between the ts marker of NDV(pi) and the other properties which distinguish this virus from NDV(o), NDV(pi) ts(+) revertants were selected at the nonpermissive temperature and NDV(o) ts mutants were generated by treating NDV(o) with nitrous acid. Spontaneously-occurring ts mutants in the Herts NDV population were also isolated. The different virus populations were characterized with regard to plaque size, virulence for eggs, and thermal stability of infectivity, hemagglutinin, and neuraminidase. The NDV(pi) ts(+) revertants, although no longer temperature-sensitive, retained NDV(pi) properties, whereas both spontaneously-occurring and mutagen-induced ts mutants remained wild-type in their other properties. These findings showed that the properties which characterized NDV(pi) were independent of the ts marker. However, the ts marker and the other markers of NDV(pi) were coselected during the persistent infection, and the combination of those markers appeared to be important in the outcome of NDV infection of L cells. NDV(pi) replicated productively in L cells, whereas NDV(o), the NDV(pi) ts(+) revertants, and the spontaneously-occurring ts mutants all yielded covert infections in L cells. The role of the selection of ts mutants in persistent infection was confirmed as follows: L cells were persistently infected with NDV(pi) ts(+) revertants and NDV(o) ts mutants. Virus recovered from the persistently infected cultures after eight cell passages was always temperature-sensitive and of smaller plaque size than the parental virus in chicken embryo cell cultures. Similar results were obtained with virus recovered from L-cell cultures persistently infected with two other velogenic strains of NDV, the Texas-GB and Kansas-Man strains. These results strongly suggest that selection of ts mutants during the persistent infection was not random and played a role in establishment or maintenance of the persistent infection, or both.     

A SYBR Green RT-PCR assay in single tube to detect human and bovine noroviruses and control for inhibition

Background

A subset of the virus-specific CD8+ cytotoxic T lymphocytes (CTL) isolated from the lungs of mice infected with human respiratory syncytial virus (RSV) is impaired in the ability to secrete interferon γ (IFNγ), a measure of functionality. It was suggested that the impairment specifically suppressed the host cellular immune response, a finding that could help explain the ability of RSV to re-infect throughout life.

Results

To determine whether this effect is dependent on the virus, the route of infection, or the type of infection (respiratory, disseminated, or localized dermal), we compared the CTL responses in mice following intranasal (IN) infection with RSV or influenza virus or IN or intradermal (ID) infection with vaccinia virus expressing an RSV CTL antigen. The impairment was observed in the lungs after IN infection with RSV, influenza or vaccinia virus, and after a localized ID infection with vaccinia virus. In contrast, we observed a much higher percentage of IFNγ secreting CD8+ lymphocytes in the spleens of infected mice in every case.

Conclusion

The decreased functionality of CD8+ CTL is specific to the lungs and is not dependent on the specific virus, viral antigen, or route of infection.     

Adenovirus E1a interferes with expression of vaccinia viral genes

The 12S and 13S cDNAs of the oncogene E1a encoded by the early region of adenovirus 12 (Ad12) were overexpressed using the T7/encephalomyocarditis (EMC)/vaccinia hybrid expression system. The E1a proteins were stable for at least 12 h in monkey epithelial BSC1 cells. The E1a proteins were recognized by a rabbit polyclonal antibody and displayed phosphorylation patterns similar to those displayed by the E1a proteins expressed in Ad12-transformed cells. Expression of E1a proteins by recombinant vaccinia virus led to inhibition of vaccinia viral protein synthesis which was observed as soon as 6 h after infection. This suppression was mediated by both the 12S and the 13S products of Ad12E1a and to a somewhat lesser extent by the 13S product of Ad2E1a. The inhibition of vaccinia virus gene expression resulted in enhanced survival of vaccinia virus-infected cells. These results suggest that the proteins encoded by the E1a sequester a viral or a cellular product(s) that is essential for the expression of vaccinia virus-encoded genes.     

THE DEVELOPMENT OF VACCINIA VIRUS IN EARLE'S L STRAIN CELLS AS EXAMINED BY ELECTRON MICROSCOPY

A favorable system which is amenable to frequent and reproducible sampling, consisting of suspension cultures of strain L cells and vaccinia virus, was employed to study the animal virus-mammalian host cell relationship. The three principal aspects investigated concerned the adsorption and penetration of vaccinia into the host, the relationship between the sequence of virus development and the production of infectious particles, and the changes in the fine structure of the host cells. Experiments in which a very high multiplicity of infection was used revealed that vaccinia is phagocytized by L cells in less than 1 hour after being added to the culture, without any apparent loss of its outer limiting membranes. Regions of dense fibrous material, thought to be foci of presumptive virus multiplication, appear in the cytoplasm 2 hours after infection. A correlation between electron microscope studies and formation of infectious particles shows that although immature forms of the virus appear 4 hours after infection, infectious particles are produced 6 hours after infection of the culture, at the time when mature forms of vaccinia appear for the first time in thinly sectioned cells. Spread of the infection is gradual until eventually, after 24 hours, virus is being elaborated throughout the cytoplasm. Addition of vaccinia to monolayer cultures induced fusion of L cells and rapid formation of multinucleate giant forms. In both suspension and stationary cultures infected cells elaborate a variety of membranous structures not present in normal L cells. These take the form of tube-like lamellar and vesicular formations, or appear as complex reticular networks or as multi-laminar membranes within degenerating mitochondria.     

The depuration dynamics of oysters (Crassostrea gigas) artificially contaminated with hepatitis A virus and human adenovirus

Within the country of Brazil, Santa Catarina is a major shellfish producer. Detection of viral contamination is an important step to ensure production quality and consumer safety during this process. In this study, we used a depuration system and ultraviolet (UV) disinfection to eliminate viral pathogens from artificially infected oysters and analysed the results. Specifically, the oysters were contaminated with hepatitis A virus (HAV) or human adenovirus type 5 (HAdV5). After viral infection, the oysters were placed into a depuration tank and harvested after 48, 72 and 96 h. After sampling, various oyster tissues were dissected and homogenised and the viruses were eluted with alkaline conditions and precipitated with polyethylene glycol. The oyster samples were evaluated by cell culture methods, as well as polymerase chain reaction (PCR) and quantitative-PCR. Moreover, at the end of the depuration period, the disinfected seawater was collected and analysed by PCR. The molecular assays showed that the HAdV5 genome was present in all of the depuration time samples, while the HAV genome was undetectable after 72 h of depuration. However, viral viability tests (integrated cell culture-PCR and immunofluorescence assay) indicated that both viruses were inactivated with 96 h of seawater recirculation. In conclusion, after 96 h of UV treatment, the depuration system studied in this work purified oysters that were artificially contaminated with HAdV5 and HAV.     

鹅源新城疫病毒ZJ1株微型基因组的构建及其初步应用

在获得鹅源新城疫病毒ZJ1株全基因组序列的基础上,用增强型绿色荧光蛋白（eGFP）报告基因取代鹅源新城疫病毒ZJ1株整个编码区,只保留与病毒复制、转录和病毒粒子包装相关的调控序列,将其反向克隆入转录载体TVT7R(0.0)中,构建了该毒株的微型基因组。当转染用辅助病毒ZJ1株感染的Hep_2细胞时报告基因得到表达,表明此微型 基因组RNA可被辅助病毒提供的NP、P和L蛋白翻译。同时将该病毒NP、P和L蛋白基因分别克隆入真核表达载体pCI_neo中,构建了表达该病毒NP、P与L蛋白的辅助质粒,用此微型基因组对辅助质粒的表达产物进行了功能鉴定并对该病毒拯救过程中痘苗病毒的最适感染剂量进行了摸索。以上研究为该病毒的成功拯救及开展其它相关研究奠定了基础。     

Differential antigen requirements for protection against systemic and intranasal vaccinia virus challenges in mice

The development of a subunit vaccine for smallpox represents a potential strategy to avoid the safety concerns associated with replication-competent vaccinia virus. Preclinical studies to date with subunit smallpox vaccine candidates, however, have been limited by incomplete information regarding protective antigens and the requirement for multiple boost immunizations to afford protective immunity. Here we explore the protective efficacy of replication-incompetent, recombinant adenovirus serotype 35 (rAd35) vectors expressing the vaccinia virus intracellular mature virion (IMV) antigens A27L and L1R and extracellular enveloped virion (EEV) antigens A33R and B5R in a murine vaccinia virus challenge model. A single immunization with the rAd35-L1R vector effectively protected mice against a lethal systemic vaccinia virus challenge. The rAd35-L1R vector also proved more efficacious than the combination of four rAd35 vectors expressing A27L, L1R, A33R, and B5R. Moreover, serum containing L1R-specific neutralizing antibodies afforded postexposure prophylaxis after systemic vaccinia virus infection. In contrast, the combination of rAd35-L1R and rAd35-B5R vectors was required to protect mice against a lethal intranasal vaccinia virus challenge, suggesting that both IMV- and EEV-specific immune responses are important following intranasal infection. Taken together, these data demonstrate that different protective antigens are required based on the route of vaccinia virus challenge. These studies also suggest that rAd vectors warrant further assessment as candidate subunit smallpox vaccines.     

Mechanism of Vaccinia Virus Release and Its Specific Inhibition by N1-Isonicotinoyl-N2-3-Methyl-4- Chlorobenzoylhydrazine

The release of vaccinia virus from RK-13 cells and its specific inhibition by N(1)-isonicotinoyl-N(2)-3-methyl-4- chlorobenzoylhydrazine (IMCBH) was studied. Intracellular naked vaccinia virus (INV) was wrapped by intracytoplasmic membranes, forming an intracellular double-membraned virion. Wrapped virions migrated to the cell surface, where the outer virion membrane presumably fused with the plasma membrane, releasing virus surrounded by the inner membrane, referred to as extracellular enveloped vaccinia virus (EEV). At no time was there any evidence that vaccinia virus acquired an envelope by budding of naked virus from the cytoplasmic membrane. Naked virus and double-membraned virus each constituted about one-third of intracellular virus at 8 and 12 h postinfection (p.i.). Beginning at 16 h p.i., the proportion of intracellular virus occurring as double-membraned virus steadily decreased to 1% at 24 h while the proportion of naked virus rose to 87%. IMCBH inhibited the formation of the double-membraned virion and the appearance of EEV while not affecting the production of INV. IMCBH had no effect on INV infectivity or polypeptide composition, on vaccinia virus-specified membrane-associated proteins or glycoproteins, or on hemadsorption. The presence of IMCBH until 4 h p.i. did not decrease the amount of EEV at 48 h p.i., whereas less than 10% of the normal 48-h EEV yield was obtained if the drug was present during the first 16 h p.i. Cell cultures infected at very low multiplicities showed a rapid virus dissemination in the absence of the drug, whereas the presence of IMCBH very effectively inhibited this spread. We conclude that vaccinia virus is liberated via a double-membraned intermediate as an enveloped virion and that it is this extracellular enveloped virus that is responsible for dissemination of infection.     

In vivo dose-response of insects to Hz-2V infection

Background

Vaccinia virus, the prototype member of the family Poxviridae, was used extensively in the past as the Smallpox vaccine, and is currently considered as a candidate vector for new recombinant vaccines. Vaccinia virus has a wide host range, and is known to infect cultures of a variety of cell lines of mammalian origin. However, little is known about the virus tropism in human leukocyte populations. We report here that various cell types within leukocyte populations have widely different susceptibility to infection with vaccinia virus.

Results

We have investigated the ability of vaccinia virus to infect human PBLs by using virus recombinants expressing green fluorescent protein (GFP), and monoclonal antibodies specific for PBL subpopulations. Flow cytometry allowed the identification of infected cells within the PBL mixture 1–5 hours after infection. Antibody labeling revealed that different cell populations had very different infection rates. Monocytes showed the highest percentage of infected cells, followed by B lymphocytes and NK cells. In contrast to those cell types, the rate of infection of T lymphocytes was low. Comparison of vaccinia virus strains WR and MVA showed that both strains infected efficiently the monocyte population, although producing different expression levels. Our results suggest that MVA was less efficient than WR in infecting NK cells and B lymphocytes. Overall, both WR and MVA consistently showed a strong preference for the infection of non-T cells.

Conclusions

When infecting fresh human PBL preparations, vaccinia virus showed a strong bias towards the infection of monocytes, followed by B lymphocytes and NK cells. In contrast, very poor infection of T lymphocytes was detected. These finding may have important implications both in our understanding of poxvirus pathogenesis and in the development of improved smallpox vaccines.     

Differential cell membrane labilizing effect of adenovirus type 5 and 12 observed during productive and abortive infection.

Culture fluid of human epitheloid (HEp-2) cells was examined for extracellular lactate dehydrogenase activity as an indicator of cell damage during a 48 h period in which virus replication and changes in cell morphology occurred. Uninfected and adenovirus type 5-infected cells had the same levels of extracellular enzyme activity both before and after the appearance of morphological changes in cells due to virus infection, whereas adenovirus type 12-infected cells showed increased extracellular enzyme activity. Cells infected with either adenovirus type 5 or type 12 had the same total cellular and extracellular lactate dehydrogenase activity. Hydrocortisone, a membrane stabilizing agent, prevented abnormal leakage of lactate dehydrogenase from adenovirus type 12-infected cells, but had no effect on virus replication or total enzyme activity of infected cells. After inoculation of monkey kidney (Vero) cells the yield of progeny adenovirus type 5 virions was greatly reduced and there was no production of adenovirus type 12 virions. The pattern of extracellular lactate dehydrogenase activity of uninfected and adenovirus type 5- and type 12-infected Vero cells was like that with HEp-2 cells. Therefore, production of adenovirus type 12 virions is not necessary for the virus-cell interaction causing cell membrane labilization.     

Tracking the spread of a lacZ-tagged herpes simplex virus type 1 between the eye and the nervous system of the mouse: comparison of primary and recurrent infection

The spread of herpes simplex virus type 1 (HSV-1) during primary ocular infection and after reactivation of latent infection in the trigeminal ganglion (TG) was examined in the mouse using a genetically modified virus containing the lacZ reporter gene under the control of the immediate-early 110 promoter. Whole tissue mounts of the eye and lids, their sensory nerves, and TG with the attached dorsal root entry zone (DRE) into the central nervous system (CNS) were stained for beta-galactosidase. Sixteen hours after inoculation of the cornea by scarification, staining was found in the scarified epithelium of the cornea and in the unscarified conjunctiva. By 24 h, staining was also seen in a few TG neurons and by 96 h their number had greatly increased and their distribution was more widespread. Stained cells (identified as Schwann cells by their staining for glial fibrillary acidic protein [GFAP] or S-100) in the TG were first seen close to stained neurons at 40 h, and by 48 h lines of such cells extended partway toward the periphery and toward the DRE. By 72 h, these lines had reached the periphery and the DRE where the adjacent CNS was also stained. In the cornea, stained cells with the morphology and arrangement of Schwann cells were seen from 40 to 120 h. After reactivation of latent infection, 10 of 22 samples had positively stained neurons. In eight samples, corneal and lid epithelial cells were stained. No stained Schwann cells were seen in the TG; however, branched networks of such cells were present in the cornea and the lids. This detailed sequential analysis has provided new information on the involvement of Schwann cells in the pathogenesis of primary and recurrent HSV-1 disease in the TG and the cornea.     

Specific secretion of polypeptides from cells infected with vaccinia virus.

The pattern of polypeptides specifically secreted by cells after infection with vaccinia virus has been analyzed. A complex pattern of apparently virus-specified polypeptides exhibiting temporal control of the type seen with intracellular polypeptides after virus infection was observed. Some of the specifically secreted polypeptides were shown to be modified by glycosylation and sulfation. The possible significance of these results is discussed.     

Differential sensitivity of normal and transformed human cells to reovirus infection.

Normal and simian virus 40-transformed WI-38 cells exhibited a differential sensitivity to infection with type 3 reovirus. A progressive decrease in viability began 24 to 36 h after infection of transformed cells terminating in complete lysis of cultures by 96 h. Normal cells were productively infected and continued to produce and release virus for as long as 14 days after infection, but exhibited no detectable cytopathology. Inhibition of cellular DNA synthesis began 15 to 18 h after infection in transformed cells before development of cytopathology. No inhibition of DNA synthesis was detected in infected normal cells. No significant differences were noted in the adsorption or early replication characteristics of reovirus in normal and transformed cells. Virus replication and host cell DNA synthesis in normal and transformed human cells were compared to reovirus-infected L-929 mouse fibroblast cells.