Neuroexcitatory actions of Tamiflu and its carboxylate metabolite

Oseltamivir (Tamiflu) is now being stockpiled by several governments as a first line treatment for an anticipated outbreak of avian influenza caused by H5N1. However, abnormal behaviors and death associated with the use of Tamiflu have developed into a major issue in Japan where Tamiflu is often prescribed for seasonal influenza. Thus, it is critical to determine neuropsychiatric effects of oseltamivir and to establish methods for safe administration. Using juvenile rats and rat hippocampal slices, we investigated whether oseltamivir has adverse effects on the central nervous system. Systemic injection of oseltamivir (50 mg/kg i.p.) produced no change in behavior within 2 h. However, prior injection of oseltamivir significantly altered the duration of loss of lightning reflex following ethanol injection (3.3 g/kg, i.p.). Ethanol injection in the presence of oseltamivir also resulted in enhanced hypothermia. In the CA1 region of hippocampal slices, oseltamivir (100 μM) induced paired-pulse facilitation in population spikes without changes in excitatory postsynaptic potentials. Similarly, 3 μM oseltamivir carboxylate, the active metabolite of oseltamivir, facilitated neuronal firing, though the facilitation did not involve GABAergic disinhibition. Moreover, oseltamivir carboxylate produced further facilitation following administration of 60 mM ethanol. These findings indicate that oseltamivir has effects on the central nervous system, especially when combined with other agents.     

Protective efficacy in chickens, geese and ducks of an H5N1-inactivated vaccine developed by reverse genetics

We generated a high-growth H5N1/PR8 virus by plasmid-based reverse genetics. The virulence associated multiple basic amino acids of the HA gene were removed, and the resulting virus is attenuated for chickens and chicken eggs. A formalin-inactivated oil-emulsion vaccine was prepared from this virus. When SPF chickens were inoculated with 0.3 ml of the vaccine, the hemagglutinin-inhibition (HI) antibody became detectable at 1 week post-vaccination (p.v.) and reached a peak of 10log2 at 6 weeks p.v. then slowly declined to 4log2 at 43 weeks p.v. Challenge studies performed at 2, 3 and 43 weeks p.v. indicated that all of the chickens were completely protected from disease signs and death. Ducks and geese were completely protected from highly pathogenic H5N1 virus challenge 3 weeks p.v. The duration of protective immunity in ducks and geese was investigated by detecting the HI antibody of the field vaccinated birds, and the results indicated that 3 doses of the vaccine inoculation in geese could induce a 34 weeks protection, while 2 doses induced more than 52 weeks protection in ducks. We first reported that an oil-emulsion inactivated vaccine derived from a high-growth H5N1 vaccine induced approximately 10 months of protective immunity in chickens and demonstrated that the oil-emulsion inactivated avian influenza vaccine is immunogenic for geese and ducks. These results provide useful information for the application of vaccines to the control of H5N1 avian influenza in poultry, including chickens and domestic waterfowl.     

Decreased cell-mediated cytotoxicity against virus-infected cells in systemic lupus erythematosus.

Cell-mediated cytotoxicity, directed against virus-infected tissue culture cells, was studied with peripheral blood mononuclear cells from 11 patients with systemic lupus erythematosus (SLE) and 12 matched, normal subjects in a 51Cr release assay. Baseline (preimmunization) levels of cytotoxicity against target cells infected with influenza A/Victoria, influenza B/Hong Kong, Newcastle disease virus, and herpes simplex virus were significantly decreased in patients with SLE compared to normal subjects (P less than 0.001), although serum antibody levels to the respective viruses were similar in both groups. After intramuscular administration of inactivated influenza A/Victoria vaccine, SLE patients failed to generate elevated levels of cytotoxicity against A/Victoria-infected cells, in contrast to normal subjects. SLE patients responded with levels of serum hemagglutination-inhibition antibody which were similar to those of normal subjects. Thus, SLE patients manifest decreased cell-mediated cytotoxicity against virus-infected target cells, although humoral antibody responses appeared to be intact. Studies of SLE patients with influenza may help to define the role of cell-mediated immunity in the pathogenesis of certain viral infections.     

Modelling HA protein-mediated interaction between an influenza virus and a healthy cell: pre-fusion membrane deformation.

We present a mathematical model for pre-fusion interaction between an influenza virus and a healthy cell. Our model describes the role played by hemagglutinin (HA) protein clusters in bringing the viral membrane into close contact with the host cell membrane as a first step of the fusion process between the two membranes. The viral membrane is modelled as a lipid bilayer with bending rigidity. Using the calculus of variations, we compute the deformation of the viral membrane under the influence of HA protein clusters. Our numerical results support the hypothesis of dimple formation in the fusion site proposed in the literature. The asymmetric nature of the protein molecules due to various reasons such as tilting is the primary cause for the dimple formation. We discuss the effects of spontaneous curvature, the protein cluster radius, fusion-site size and the bending moment exerted by the protein cluster. We also examine the effects of membrane tension and the presence of a host cell on the dimple shape. Our results support previous experimental observations.     

Protective Cellular Immunity Against Influenza Virus Induced by Plasmid Inoculation of Newborn Mice

Neonate organisms display an intrinsic disability to mount effective immune responses to infectious agents or conventional vaccines. Whereas low. doses of antigens trigger a suboptimal response, higher doses are frequently associated with tolerance induction. We investigated the ability of a plasmid-expressing nucleoprotein of influenza virus to prime a specific cellular immune response when administered to newborn mice. We found that persistent exposure to antigen following plasmid inoculation of neonates leads to a vigorous priming of specific CTLs rather than tolerance induction. The CTLs were cross-reactive against multiple strains of type A influenza viruses and produced IFNγ but no IL-4. The immunity triggered by plasmid inoculation of neonates was protective in terms of pulmonary virus clearance as well as survival rate following lethal challenge with influenza virus. Whereas the persistence of the plasmid at the site of injection was readily demonstrable in adult mice at 3 months after inoculation, mice immunized as newborns displayed no plasmid at 3 months and very little at 1 month after injection. Thus, DNA-based immunization of neonates may prove an effective and safe vaccination strategy for induction of cellular immunity against microbes that cause serious infectious diseases in the early period of life.     

Effects of Killed and Live Attenuated Influenza Vaccine on Symptoms and Specific Airway Conductance in Asthmatics and Healthy Subjects

Killed and live influenza virus vaccines were given to asthmatics and healthy subjects to investigate symptoms and alterations in their respiratory performance after vaccination. Polyvalent killed influenza virus vaccine was given to 16 asthmatics and live attenuated influenza virus vaccine to 23 asthmatics and 21 healthy subjects. Fourteen of the 16 asthmatics vaccinated with the killed vaccine displayed a significant rise in serum antibody level as measured by a single radial haemolysis in gel (SRH test). 11 of the 23 asthmatics and 14 of the 21 healthy subjects vaccinated with the live attenuated vaccine displayed a significant rise in the SRH test. Among the subjects with no measurable initial antibodies and with a significant rise in the SRH test, one asthmatic vaccinated with the killed vaccine experienced symptoms of common cold with fever and dyspnoea 1 week after vaccination. Three asthmatics and four healthy subjects vaccinated with live attenuated vaccine experienced mild symptoms, mainly rhinorrhoea, cough and sore throat 2 to 3 days after vaccination. No alterations in specific airway conductance in asthmatics or in healthy subjects were observed. We conclude that both killed and live attenuated influenza virus vaccines are tolerated well by asthmatics and appear to be safe for asthma patients.     

Nucleotide sequence of RNA segment 3 of the avian influenza A/FPV/Rostock/34 and its comparison with the corresponding segment of human strains A/PR/8/34 and A/NT/60/68

The nucleotide sequence of RNA segment 3 of A/FPV/Rostock/34 (H7N1), an avian strain of influenza A virus, has been determined from a cloned DNA copy. Segment 3 codes for the PA polypeptide and the sequence specifies an acidic polypeptide of 716 amino acid residues. Comparison of the sequence with the corresponding segment of two human strains A/PR/8/34 and A/NT/60/68 indicates significant divergence of the avian sequence from the human sequences at the nucleotide level. At the amino acid level there is considerably greater homology between the avian and human strains. This presumably reflects a constraint on divergence of the PA polypeptide imposed by a common functional requirement of PA in all influenza virus strains.     

一起学校流感暴发的调查和分析

目的调查此次疫情暴发的原因和特点，防止类似疫情再次发生。方法按2005年广东省卫生厅《广东省流感样病例暴发疫情报告及调查处理工作指引（试行）》进行。结果全校学生902人，发病74例，罹患率为8．20％。整个疫情流行过程为17日，7—9岁年龄组发病较多，男女发病无显著差别。一、二年级学生和在校午休学生罹患率较高，具明显的班级和宿舍聚集性；病毒分离培养为B型流感病毒。结论此次为一起由B型流感病毒引起的流感暴发疫情，暴发原因为未及时隔离治疗病人、疫情报告迟缓、室内通风换气不够和学校未开展流感疫苗接种等。     

Immune response of adults to sequential influenza vaccination

Annual immunization against influenza is recommended for numerous individuals, but the antibody response to sequential vaccination has not been well characterized. Levels of hemagglutination-inhibition antibody were measured in adults given either two or three doses of trivalent influenza vaccine at six-month intervals. A significant rise in the number of individuals with antibody titers of greater than or equal to 40 was seen for all three antigens only after initial vaccination. Repeated vaccination was necessary to maintain adequate antibody levels only to the A/Brazil (H1N1) antigen; it did not significantly affect the proportions of individuals with protective levels of antibody to either the A/Bangkok (H3N2) or the B/Singapore 222/79 antigens. These findings do not support the current recommendation for annual immunization when the vaccine formulation has not changed.