Statolon-induced resistance of mice to mengovirus

Mice receiving statolon intraperitoneally were 1,000 times more resistant to intraperitoneal challenge with mengovirus than were untreated controls. Protection was afforded when statolon was administered 1 day before or 1 day after intraperitoneal inoculation with the virus. No therapeutic effect was observed when treatment with statolon was delayed for 2 days or more after virus infection. Exposure of mice to a simulated space cabin environment did not increase their susceptibility to the lethal effects of mengovirus infection or eliminate the protective effect of statolon.     

Influence of Statolon on Resistance of Mice to Influenza

Various interferon inducers are known to elicit protection against lethal or infecting doses of certain viral agents. Because of the relatively high morbidity rate of influenza and its seasonal occurrence, we wished to determine whether statolon-induced interferon might be effective in controlling this disease. Mice were treated intraperitoneally with statolon and challenged with influenza A(2) virus by the intranasal route. Although interferon was present in the serum at the time of virus administration, no change in mortality rate was observed. There was, however, a significant increase in the mean survival time of treated animals. Similar results were obtained when Newcastle disease virus was used as the interferon inducer. To determine the effect of the route of challenge, other mice were treated with statolon or Newcastle disease virus and inoculated with mengovirus by the intranasal or intraperitoneal route. The results demonstrated that the treated mice were protected to similar degree against challenge by either route. It is suggested that the relative ineffectiveness of interferon in protecting mice against influenza is due to an intrinsic characteristic of the virus itself rather than the type of interferon induced or the route of virus challenge.     

Protective Efficacy of Passive Immunization with Monoclonal Antibodies in Animal Models of H5N1 Highly Pathogenic Avian Influenza Virus Infection

Highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype often cause severe pneumonia and multiple organ failure in humans, with reported case fatality rates of more than 60%. To develop a clinical antibody therapy, we generated a human-mouse chimeric monoclonal antibody (MAb) ch61 that showed strong neutralizing activity against H5N1 HPAI viruses isolated from humans and evaluated its protective potential in mouse and nonhuman primate models of H5N1 HPAI virus infections. Passive immunization with MAb ch61 one day before or after challenge with a lethal dose of the virus completely protected mice, and partial protection was achieved when mice were treated 3 days after the challenge. In a cynomolgus macaque model, reduced viral loads and partial protection against lethal infection were observed in macaques treated with MAb ch61 intravenously one and three days after challenge. Protective effects were also noted in macaques under immunosuppression. Though mutant viruses escaping from neutralization by MAb ch61 were recovered from macaques treated with this MAb alone, combined treatment with MAb ch61 and peramivir reduced the emergence of escape mutants. Our results indicate that antibody therapy might be beneficial in reducing viral loads and delaying disease progression during H5N1 HPAI virus infection in clinical cases and combined treatment with other antiviral compounds should improve the protective effects of antibody therapy against H5N1 HPAI virus infection.     

Treatment of mengovirus infection in mice with statolon

A single intraperitoneal injection of statolon was shown to exert a therapeutic effect on mice previously injected with the large plaque-forming variant of mengovirus. The ld(50) and survival time data demonstrated that such treatment was effective when given 2 to 48 hr after infection. No protective effect was apparent when statolon was administered 3, 4, or 5 days after the viral challenge. It was concluded that statolon, or other similar interferon inducers, may be of therapeutic value in instances of accidental or other known exposure to hazardous viral agents.     

Melatonin treatment enhances the efficiency of mice immunization with Venezuelan equine encephalomyelitis virus TC-83

To determine whether treatment with melatonin (MLT) improves the efficiency of immunization against Venezuelan equine encephalomyelitis (VEE) virus, mice were vaccinated with TC-83 VEE virus and treated daily with MLT (1 or 5 mg/kg) starting 3 days before immunization, until 10 days after. IgM antibody titers were determined at days 7, 14, and 21 post-immunization. IL-10 levels were assayed at day 14 postvaccination. Treatment with MLT increased antibody titers 14 days after the immunization. IL-10 levels also increased with MLT treatment (1 and 5 mg/kg). Mice were challenged with live VEE virus at day 21 postimmunization, and viral titers were plaque assayed in chicken embryo fibroblasts 4 days after the infection. Following this challenge brain virus levels were significantly reduced. The results suggest that MLT treatment enhances the efficiency of mice immunization against VEE virus.     

Effect of rIFN-gamma and IL-2 treatments in mouse and nude rat infections with Toxoplasma gondii.

Mice and nude rats lethally infected with T. gondii and treated with recombinant rat interferon-gamma (rIFN-gamma) or recombinant human interleukin-2 (rIL-2) were protected against death, when compared with untreated infected controls. In mice rIFN-gamma and rIL-2 played an important role in "prophylactic treatment", but not in "curative therapy". The survival rate was 42% in mice treated with 3 doses of 20,000 U of rIFN-gamma at days -2, -1, 0 before challenge and up to 66% in mice treated with 3 doses of 10,000 U of rIFN-gamma at days -2, 0, +2 before and after infection. Whereas the survival rate was 33% in mice that received 3 doses of 500 U rIL-2 at days -2, -1, 0 before infection, or -2, 0, +2 before and after infection respectively, up to 50% of the mice treated with 3 doses of 1,000 U rIL-2 at days -2, -1, 0 survived. In nude rats rIFN-gamma had a slight effect in "prophylactic treatment", whereas rIL-2 was active only in "curative treatment". The survival rate was 25% both in nude rats treated with doses of 400,000 U of rIFN-gamma at days -3, 0 before challenge, or with doses of 5,000 U of rIL-2 at days +2, +6, +9 after infection. These results lead us to hypothesise that the mechanism by which the lymphokine treatment exerts a protective effect on Toxoplasma infected mice is different from that on nu/nu rats. We conclude that these cytokines may play a notable role in modulating the host's immune defence against T. gondii infection.     

Humoral immunity and protection of mice challenged with homotypic or heterotypic parvovirus.

BACKGROUND AND OBJECTIVES: Two serotypes of autonomously replicating parvoviruses infect laboratory mice. Genome regions coding for the nonstructural proteins of minute virus of mice [MVM] and mouse parvovirus [MPV] are almost identical, whereas capsid-coding sequences are divergent. We addressed these questions: Does humoral immunity confer protection from acute infection after challenge with homotypic or heterotypic parvovirus, and if it confers protection against acute MPV infection, does it also protect against persistent MPV infection? METHODS: Infant mice without maternal antibody or antibody to MVM or MPV and young adult mice given normal mouse serum or antibody to MVM or MPV were challenged with homotypic or heterotypic virus. In situ hybridization with target tissues was the indicator of infection. RESULTS: Humoral immunity failed to confer protection against acute heterotypic parvovirus infection. In passive transfer studies, MPV DNA was observed occasionally in lymph nodes, intestine, or the spleen of MPV-challenged mice given homotypic antibody and kept for 6 or 28 days. Variable proportions of mice given MPV antibody and homotypic challenge had viral DNA in lymphoid tissues 56 days after virus inoculation. CONCLUSION: A mouse or colony that has sustained infection with MVM or MPV is probably fully susceptible to infection with the heterotypic virus.     

Resistance to fatal central nervous system disease by mouse hepatitis virus, strain JHM. II. Adherent cell-mediated protection

Resistance of SJL/J mice to intracranial inoculation with the JHM strain of mouse hepatitis, a coronavirus, is dependent upon the age of the animals at inoculation. Animals 12 weeks of age or older are resistant, whereas those 6 weeks or younger are uniformly susceptible to viral infection. Spleen cells or thioglycolate elicited peritoneal exudate cells can transfer resistance from 12-week-old to 6-week-old recipients. Removal of the adherent cells from either spleen or peritoneal cells ablated protection. Adherent cells from 12-week-old mice were protective even after depletion of Ia- and Thy-1-bearing cells. Antiviral antibody, thioglycolate injection into 6-week-old animals, and nylon wool-purified T cells were ineffective in mediating resistance. Adherent cells transferred 4 days before virus challenge, but not after challenge, were protective. Thus, there is an age-related change in SJL mice that protects from acute central nervous system disease, which may be due to maturation of a specialized adherent cell population.     

IFN mimetic as a therapeutic for lethal vaccinia virus infection: possible effects on innate and adaptive immune responses

We have developed small peptide mimetics of IFN-gamma that can bypass the poxvirus virulence factor B8R protein, which binds to intact IFN-gamma and prevents its interaction with receptor extracellular domain. Thus, these peptides inhibit vaccinia virus replication in cell culture where intact IFN-gamma is ineffective. We demonstrate here that the mouse IFN-gamma-mimetic peptide, IFN-gamma(95-132), protects C57BL/6 mice against overwhelming lethal vaccinia virus infection. The mimetic peptide was synthesized with an attached lipophilic group for penetration of cell plasma membrane. Injection of mimetic i.p. before and at the time of intranasal (10(6) PFU) or i.p. (10(7) PFU) challenge with virus resulted in complete protection at 200 microg of mimetic and 40-60% protection at 5 microg of mimetic. Initiation of treatment of mice with IFN-gamma mimetic up to 2 days postinfection resulted in complete protection against death, whereas initiation of treatment at 6 days postinfection resulted in 40% protection. Administration of mimetic by the oral route also completely protected mice against the intranasal route of a lethal dose of vaccinia virus challenge. In addition to its direct antiviral effect, the mimetic also possessed adjuvant effects in boosting humoral and cellular immunity to vaccinia virus. The combination of antiviral and adjuvant effects by the IFN mimetic probably plays a role in its potent anti-vaccinia virus properties. These results suggest an effective therapeutic against ongoing, lethal poxvirus infections that taps into innate and adaptive host defenses.     

Ebola GP-specific monoclonal antibodies protect mice and guinea pigs from lethal Ebola virus infection

Ebola virus (EBOV) causes acute hemorrhagic fever in humans and non-human primates with mortality rates up to 90%. So far there are no effective treatments available. This study evaluates the protective efficacy of 8 monoclonal antibodies (MAbs) against Ebola glycoprotein in mice and guinea pigs. Immunocompetent mice or guinea pigs were given MAbs i.p. in various doses individually or as pools of 3-4 MAbs to test their protection against a lethal challenge with mouse- or guinea pig-adapted EBOV. Each of the 8 MAbs (100 μg) protected mice from a lethal EBOV challenge when administered 1 day before or after challenge. Seven MAbs were effective 2 days post-infection (dpi), with 1 MAb demonstrating partial protection 3 dpi. In the guinea pigs each MAb showed partial protection at 1 dpi, however the mean time to death was significantly prolonged compared to the control group. Moreover, treatment with pools of 3-4 MAbs completely protected the majority of animals, while administration at 2-3 dpi achieved 50-100% protection. This data suggests that the MAbs generated are capable of protecting both animal species against lethal Ebola virus challenge. These results indicate that MAbs particularly when used as an oligoclonal set are a potential therapeutic for post-exposure treatment of EBOV infection.     

Immunization with SARS coronavirus vaccines leads to pulmonary immunopathology on challenge with the SARS virus

Background

Severe acute respiratory syndrome (SARS) emerged in China in 2002 and spread to other countries before brought under control. Because of a concern for reemergence or a deliberate release of the SARS coronavirus, vaccine development was initiated. Evaluations of an inactivated whole virus vaccine in ferrets and nonhuman primates and a virus-like-particle vaccine in mice induced protection against infection but challenged animals exhibited an immunopathologic-type lung disease.

Design

Four candidate vaccines for humans with or without alum adjuvant were evaluated in a mouse model of SARS, a VLP vaccine, the vaccine given to ferrets and NHP, another whole virus vaccine and an rDNA-produced S protein. Balb/c or C57BL/6 mice were vaccinated IM on day 0 and 28 and sacrificed for serum antibody measurements or challenged with live virus on day 56. On day 58, challenged mice were sacrificed and lungs obtained for virus and histopathology.

Results

All vaccines induced serum neutralizing antibody with increasing dosages and/or alum significantly increasing responses. Significant reductions of SARS-CoV two days after challenge was seen for all vaccines and prior live SARS-CoV. All mice exhibited histopathologic changes in lungs two days after challenge including all animals vaccinated (Balb/C and C57BL/6) or given live virus, influenza vaccine, or PBS suggesting infection occurred in all. Histopathology seen in animals given one of the SARS-CoV vaccines was uniformly a Th2-type immunopathology with prominent eosinophil infiltration, confirmed with special eosinophil stains. The pathologic changes seen in all control groups lacked the eosinophil prominence.

Conclusions

These SARS-CoV vaccines all induced antibody and protection against infection with SARS-CoV. However, challenge of mice given any of the vaccines led to occurrence of Th2-type immunopathology suggesting hypersensitivity to SARS-CoV components was induced. Caution in proceeding to application of a SARS-CoV vaccine in humans is indicated.     

A protective role of locally administered immunostimulatory CpG oligodeoxynucleotide in a mouse model of genital herpes infection

Unmethylated CpG dinucleotides in bacterial DNA or synthetic oligodeoxynucleotides (ODNs) are known as potent activators of the immune system and inducers of several Th1-associated immunomodulatory cytokines. We therefore investigated whether such a CpG-containing ODN (CpG ODN) given mucosally in the female genital tract could enhance innate immunity and protect against genital herpes infection. Groups of C57BL/6 mice were treated intravaginally with either CpG ODN or a non-CpG ODN control in the absence of any antigen either 2 days before or 4 h after an intravaginal challenge with a normally lethal dose of herpes simplex virus type 2 (HSV-2). Mice treated with CpG ODN exhibited significantly decreased titers of HSV-2 in their vaginal fluids compared with non-CpG ODN-treated mice. Furthermore, CpG ODN pretreatment significantly protected against development of disease and death compared to non-CpG ODN pretreatment. Most strikingly, CpG ODN conferred protection against disease and death even when given after the viral challenge. The CpG ODN-induced protection was associated with a rapid production of gamma interferon (IFN-gamma), interleukin-12 (IL-12), IL-18, and RANTES in the genital tract mucosa following CpG ODN treatment. The observed protection appeared to be dependent on IFN-gamma, IL-12, IL-18, and T cells, as CpG ODN pretreatment did not confer any significant protection in mice deficient in IFN-gamma, IL-12, IL-18, or T cells. Further, a complete protective immunity to reinfection was elicited in CpG ODN-treated, HSV-2-challenged mice, suggesting a role for mucosally administered CpG ODN in inducing the development of an acquired immune response in addition to its potent stimulation of innate immunity.     

Fansidar prophylaxis, therapy, and immune responses in rodent malaria (Plasmodium berghei)

In order to determine the effect of Fansidar on plasmodial infection in mice, outbred, adult, Swiss-Webster mice were treated with Fansidar (20 mg sulfadoxine and 1 mg pyrimethamine/kg body weight) at various intervals before and/or after inoculation with blood stages of Plasmodium berghei. Drug therapy resulted in cure if it was given before the parasitemia rose to 53%. Oral administration of Fansidar was more effective in reducing or preventing parasitemia than intramuscular injection. Fatal infections were prevented if mice were treated orally with one dose of Fansidar 2 days before inoculation with P. berghei, whereas only partial protection occurred in animals treated 4 or more days before inoculation. Fansidar administered on two consecutive days provided protection if the drug was given at 3 and 2 days before inoculation. Administration of Fansidar for three consecutive days protected all animals if given on days 8 to 6 before inoculation. After oral administration of Fansidar, the parasitemia dropped dramatically and was undetectable at 60 hr. At 12 hr after oral treatment, schizonts and trophozoites were numerous, but there were few merozoites. Schizonts were the predominant stage at 24 hr, whereas merozoites predominated at 36 hr. Swiss-Webster and C57BL/6 mice became immune to a lethal dose of P. berghei after 4 cycles of inoculation and drug cure. Protective immunity was still present at 472 days after the fifth parasite inoculation.     

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.     

Adenovirus vectored IFN-α protects mice from lethal challenge of Chikungunya virus infection

Chikungunya virus (CHIKV) is a mosquito-borne pathogen that is responsible for numerous large and geographical epidemics, causing millions of cases. However, there is no vaccine or therapeutics against CHIKV infection available. Interferon-alpha (IFN-α) has been shown to produce potent antiviral responses during viral infection. Herein we demonstrated the use of an adenovirus-vectored expressed mouse IFN-α (mDEF201) as a prophylactic and therapeutic treatment against CHIKV in vivo. 6-day-old BALB/c mice were pre- or post-treated intranasally with single dose of mDEF201 at 5 x 10⁶ PFU per mouse and challenged with lethal dose of CHIKV. Complete survival protection was observed in mice upon a single dose of mDEF201 administration 1 days prior to virus challenge. Viral load in the serum and multiple organs were significantly reduced upon mDEF201 administration in a dose dependent manner as compare with adenovirus 5 vector placebo set. Histological analysis of the mice tissue revealed that mDEF201 could significantly reduce the tissue morphological abnormities, mainly infiltration of immune cells and muscle fibre necrosis caused by CHIKV infection. In addition, administration of mDEF201 at 6 hours post CHIKV challenge also showed promising inhibitory effect against viral replication and dissemination. In conclusion, single-dose of intranasal administration with mDEF201 as a prophylactic or therapeutic agent within 6 hours post CHIKV infection is highly protective against a lethal challenge of CHIKV in the murine model.     

Protection of inactivated influenza virus vaccine against lethal influenza virus infection in diabetic mice

Influenza virus infection frequently causes complications and some excess mortality in the patients with diabetes. Vaccination is an effective measure to prevent influenza virus infection. In this paper, antibody response and protection against influenza virus infection induced by vaccination were studied in mouse model of diabetes. Healthy and diabetic BALB/c mice were immunized once or twice with inactivated influenza virus vaccine at various dosages. Four weeks after the first immunization or 1 week after the second immunization, the mice were challenged with influenza virus at a lethal dose. The result showed that the antibody responses in diabetic mice were inhibited. Immunization once with high dose or twice with low dose of vaccine provided full protection against lethal influenza virus challenge in diabetic mice, however, in healthy mice, immunization only once with low dose provided a full protection.     

Combinations of polyclonal or monoclonal antibodies to proteins of the outer membranes of the two infectious forms of vaccinia virus protect mice against a lethal respiratory challenge

Previous studies demonstrated that antibodies to live vaccinia virus infection are needed for optimal protection against orthopoxvirus infection. The present report is the first to compare the protective abilities of individual and combinations of specific polyclonal and monoclonal antibodies that target proteins of the intracellular (IMV) and extracellular (EV) forms of vaccinia virus. The antibodies were directed to one IMV membrane protein, L1, and to two outer EV membrane proteins, A33 and B5. In vitro studies showed that the antibodies to L1 neutralized IMV and that the antibodies to A33 and B5 prevented the spread of EV in liquid medium. Prophylactic administration of individual antibodies to BALB/c mice partially protected them against disease following intranasal challenge with lethal doses of vaccinia virus. Combinations of antibodies, particularly anti-L1 and -A33 or -L1 and -B5, provided enhanced protection when administered 1 day before or 2 days after challenge. Furthermore, the protection was superior to that achieved with pooled immune gamma globulin from human volunteers inoculated with live vaccinia virus. In addition, single injections of anti-L1 plus anti-A33 antibodies greatly delayed the deaths of severe combined immunodeficiency mice challenged with vaccinia virus. These studies suggest that antibodies to two or three viral membrane proteins optimally derived from the outer membranes of IMV and EV, may be beneficial for prophylaxis or therapy of orthopoxvirus infections.     

A mouse model of the pathogenesis and postexposure prophylaxis of rabies

A mouse model for the study of postexposure prophylaxis of rabies was established. Mice injected intramuscularly with a street strain of rabies virus were significantly protected from death by five daily 0.2-ml doses of inactivated rabies vaccine of chick embryo cell culture origin initiated immediately or 3 hr after infection. In these mice, a large amount of circulating interferon was induced as early as 1 hr after the first dose of vaccine and lasted until at least 12 hr but no such amount of interferon was induced by additional doses of vaccine. Serum antibody was first detected in the mice on day 6. It was noted that some of the surviving mice manifested an ataxia or paralysis of the legs. Increasing mortality rates were shown in mice treated with decreasing doses of the vaccine. Passive protection tests using concentrated IgG and IgM antibodies with equivalent neutralization titers showed that IgG antibody gave total protection when given 24 hr before the infection, while it was almost totally ineffective in reducing the mortality when given 2 days or more after infection. IgM antibody did not protect the mice even when given 24 hr before infection. These results suggest that interferon production is more important than antibody production in the initial stages of protection by postexposure vaccination. However, the mechanisms of postexposure prophylaxis in this model could not be explained only by the interferon produced by the vaccine and the possible contributions of additional mechanisms were suggested.     

Protection of the villus epithelial cells of the small intestine from rotavirus infection does not require immunoglobulin A

Immunoglobulin A (IgA) is the primary immune response induced in the intestine by rotavirus infection, but vaccination with virus-like particles induces predominantly IgG, not IgA. To definitively assess the role of IgA in protection from rotavirus infection, IgA knockout mice, which are devoid of serum and secretory IgA, were infected and then rechallenged with murine rotavirus at either 6 weeks or 10 months. Following primary rotavirus infection, IgA knockout mice cleared virus as effectively as IgA normal control mice. Rotavirus-infected IgA knockout mice produced no serum or fecal IgA but did have high levels of antirotavirus serum IgG and IgM and fecal IgG, whereas IgA normal control mice made both serum IgA and IgG and fecal IgA. Both IgA normal and IgA knockout mice were totally protected from rotavirus challenge at 42 days. Ten months following a primary infection, both IgA normal and knockout mice still had high levels of serum and fecal antirotavirus antibody and were totally protected from rotavirus challenge. To determine if compensatory mechanisms other than IgG were responsible for protection from rotavirus infection in IgA knockout mice, mice were depleted of CD4(+) T cells or CD8(+) T cells. No changes in the level of protection were seen in depleted mice. These data show that fecal or systemic IgA is not essential for protection from rotavirus infection and suggest that in the absence of IgA, IgG may play a significant role in protection from mucosal pathogens.     

Enhanced survival of shrimp, Penaeus (Marsupenaeus) japonicus from white spot syndrome disease after oral administration of recombinant VP28 expressed in Brevibacillus brevis

White spot syndrome virus (WSSV) disease is a major threat to shrimp culture worldwide. Here, we assessed the efficacy of the oral administration of purified recombinant VP28, an envelope protein of WSSV, expressed in a Gram-positive bacterium, Brevibacillus brevis, in providing protection in shrimp, Penaeus japonicus, upon challenge with WSSV. Juvenile shrimp (2-3g in body weight) fed with pellets containing purified recombinant VP28 (50mug/shrimp) for 2weeks showed significantly higher survival rates than control groups when challenged with the virus at 3days after the last day of feeding. However, when shrimp were challenged 2weeks after the last day of feeding, survival rates decreased (33.4% and 24.93%, respectively). Survival rate was dose-dependent, increasing from 60.7 to 80.3% as the dose increased from 1 to 50mug/shrimp. At a dose of 50mug/shrimp, the recombinant protein provided protection as soon as 1day after feeding (72.5% survival). Similar results were obtained with larger-sized shrimp. These results show that recombinant VP28 expressed in a Gram-positive bacterium is a potential oral vaccine against WSSV.