The potential threat of smallpox as a bioweapon has led to the production and stockpiling of smallpox vaccine in some countries. Human monkeypox, a rare but important viral zoonosis endemic to central and western Africa, has recently emerged in the United States. Thus, even though smallpox has been eradicated, a vaccinia virus vaccine that can induce protective immunity against smallpox and monkeypox is still invaluable. The ability of the highly attenuated vaccinia virus vaccine strain LC16m8, with a mutation in the important immunogenic membrane protein B5R, to induce protective immunity against monkeypox in nonhuman primates was evaluated in comparison with the parental Lister strain. Monkeys were immunized with LC16m8 or Lister and then infected intranasally or subcutaneously with monkeypox virus strain Liberia or Zr-599, respectively. Immunized monkeys showed no symptoms of monkeypox in the intranasal-inoculation model, while nonimmunized controls showed typical symptoms. In the subcutaneous-inoculation model, monkeys immunized with LC16m8 showed no symptoms of monkeypox except for a mild ulcer at the site of monkeypox virus inoculation, and those immunized with Lister showed no symptoms of monkeypox, while nonimmunized controls showed lethal and typical symptoms. These results indicate that LC16m8 prevents lethal monkeypox in monkeys, and they suggest that LC16m8 may induce protective immunity against smallpox.

Advanced age is a risk factor of severe acute respiratory syndrome (SARS) in humans. To understand its pathogenesis, we developed an animal model using BALB/c mice and the mouse-passaged Frankfurt 1 isolate of SARS coronavirus (SARS-CoV). We examined the immune responses to SARS-CoV in both young and adult mice. SARS-CoV induced severe respiratory illness in all adult, but not young, mice on day 2 after inoculation with a mortality rate of 30 to 50%. Moribund adult mice showed severe pulmonary edema and diffuse alveolar damage accompanied by virus replication. Adult murine lungs, which had significantly higher interleukin (IL)-4 and lower IL-10 and IL-13 levels before infection than young murine lungs, rapidly produced high levels of proinflammatory chemokines and cytokines known to induce macrophage and neutrophil infiltration and activation (eg , tumor necrosis factor-␣). On day 2 after inoculation , young murine lungs produced not only proinflammatory cytokines but also IL-2 , interferon-␥ , IL-10 , and IL-13. Adult mice showed early and acute excessive proinflammatory responses (ie , cytokine storm) in the lungs after SARS-CoV infection , which led to severe pulmonary edema and diffuse alveolar damage. Intravenous injection with anti-tumor necrosis factor-␣ antibody 3 hours after infection had no effect on SARS-CoV infection. However , intraperitoneal interferon-␥ injection protected adult mice from the lethal respiratory illness. The experimental model described here may be useful for elucidating the pathophysiology of SARS and for evaluating therapies to treat SARS-CoV infection.

Enterovirus 71 (EV71) is a causative agent of hand, foot, and mouth disease and is also sometimes associated with serious neurological disorders. In this study, we characterized the antigenicity and tissue specificity of an attenuated strain of EV71 [EV71(S1-3)], which belongs to genotype A, in a monkey infection model. Three cynomolgus monkeys were inoculated with EV71(S1-3), followed by lethal challenge with the parental virulent strain EV71(BrCr-TR) via an intravenous route on day 45 postinoculation of EV71(S1-3). Monkeys inoculated with EV71(S1-3) showed a mild neurological symptom (tremor) but survived lethal challenge by virulent EV71(BrCr-TR) without exacerbation of the symptom. The immunized monkey sera showed a broad spectrum of neutralizing activity against different genotypes of EV71, including genotypes A, B1, B4, C2, and C4. For the strains examined, the sera showed the highest neutralization activity against the homotype (genotype A) and the lowest neutralization activity against genotype C2. The order of decreasing neutralization activity of sera was as follows: A > B1 > C4 > B4 > C2. To examine the tissue specificity of EV71(S1-3), two monkeys were intravenously inoculated with EV71(S1-3), followed by examination of virus distribution in the central nervous system (CNS) and extraneural tissues. In the CNS, EV71(S1-3) was isolated only from the spinal cord. These results indicate that EV71(S1-3) acts as an effective antigen, although this attenuated strain was still neurotropic when inoculated via the intravenous route.Enterovirus 71 (EV71) is a small nonenveloped virus with a genome of single-strand positive RNA of about 7,500 nucleotides and belongs to the genus Enterovirus of the family Picornaviridae (8, 48). EV71 is classified as Human enterovirus species A along with some coxsackie A (CA) viruses, such as CA10 and CA16 (8, 44). CA10, CA16, and EV71 cause hand, foot, and mouth disease (HFMD) and herpangina. EV71 infection is also sometimes associated with severe neurological diseases, such as brain stem encephalitis and poliomyelitis-like paralysis, mainly in infants and young children (11,34,56). The neuropathogenic features of EV71 were first emphasized during an outbreak in Bulgaria in 1975 in which poliomyelitis-like paralysis was the major symptom (21.1% of patients), with a high fatality rate (29.5%) among the paralytic cases (51). In recent large-scale outbreaks of HFMD in Malaysia (1997) (1, 50) and Taiwan (1998 and2000) (20,28,29,55), several fatal encephalitis cases were reported. In the EV71 outbreak in Taiwan in 1998, out of 129,106 cases of HFMD or herpangina, there were 405 severe cases, including 78 fatal cases (20); thus, the severity rate of this outbreak was Ͻ0.3%. These findings underscore the high neuropathogenicity of EV71 as well as poliovirus (PV), which causes poliomyelitis in 0.1 to 1.0% of infected individuals (reviewed in reference 36).Most of the fatal EV71 cases in Taiwan were in young children (age, Յ5 years) and involved pulmonary edema and/or pulmonary hemorrha...

Monkeypox virus is divided into Congo Basin and West African strains. The virulence and pathophysiology of two strains, Zr-599 (a Congo Basin monkeypox virus) and Liberia (a West African monkeypox virus), were evaluated in non-human primates. Four monkeys were infected by the subcutaneous (SC) and two by the intranasal (IN) inoculation routes for Zr-599 and Liberia at a dose of 10 6 p.f.u. One monkey in the Liberia/SC group was demonstrated to be co-infected with Gram-positive cocci and was excluded from analyses. Infections in three of the four Zr-599/ SC monkeys and in one of the three Liberia/SC monkeys were fatal. Virus genome levels in blood in the Zr-599/SC monkeys were approximately 10 times higher than those in the Liberia/SC monkeys. Zr-599 affected respiratory, genito-urinary and gastrointestinal tract organs more severely than Liberia. Zr-599 was more virulent than Liberia and one of the factors might be the difference in organ tropism.

These results suggest that rabphilin-3A is a major autoantigen in LINH. Autoantibodies to rabphilin-3A may serve as a biomarker for the diagnosis of LINH and be useful for the differential diagnosis in patients with CDI.