Therapeutic and prophylactic applications of bacteriophage components in modern medicine.

As the interactions of phage with mammalian innate and adaptive immune systems are better delineated and with our ability to recognize and eliminate toxins and other potentially harmful phage gene products, the potential of phage therapies is now being realized. Early efforts to use phage therapeutically were hampered by inadequate phage purification and limited knowledge of phage-bacterial and phage-human relations. However, although use of phage as an antibacterial therapy in countries that require controlled clinical studies has been hampered by the high costs of patient trials, their use as vaccines and the use of phage components such as lysolytic enzymes or lysozymes has progressed to the point of commercial applications. Recent studies concerning the intimate associations between mammalian hosts and bacterial and phage microbiomes should hasten this progress.

Is sporadic Alzheimer's disease associated with diphtheria toxin?

The two major aspects of Alzheimer's disease (AD) that must be considered in a search for causative agents are its association with aging and its widespread epidemiology. While a number of agents have been identified, additional factors may play a role. An association with diphtheria toxin was suggested by observations that vaccinations may provide protective effects, and the observation that decreased proteins synthesis in cortical regions from AD patients is associated with modification of elongation factor 2, the target of diphtheria toxin. While protection against diphtheria toxin is provided by vaccination, the known decline in the immune system associated with aging would result in a renewed sensitivity to the toxin. An association with diphtheria toxin would be consistent with the observations that the bacteria associated with the toxin, Corynebacterium diphtheria, is often found in the nasopharynx and an early symptom of AD is the loss of smell with a disease progression from the entorhinal cortex to the hippocampus and the neocortical areas. If diphtheria toxin is involved in sporadic AD, booster vaccinations given to elderly individuals might result in a decreased incidence of this disease. As booster DPT vaccinations are already recommended for individuals over 65, cognitive testing at the time of the booster and 5 years later, along with similar cognitive testing in age-matched individuals who decline vaccination, might provide an inexpensive method to investigate whether diphtheria toxin plays a role in AD and the efficacy of DPT booster vaccines for AD.

An amino acid substitution in a capsid protein enhances phage survival in mouse circulatory system more than a 1000-fold.

In experiments with germ free mice, free from adaptive antibodies to the bacterial virus lambda phage, titers of the virus in the circulatory system have been reported to decrease by more than 10(9)pfu within 48 h of intraperitoneal intravenous or oral administration. Based on these observations, serial passage techniques have been used to select lambda phage mutants, with 13,000-16,000-fold greater capacity to remain in the mouse circulatory system 24h after intraperitoneal injection. In these prior studies the "long-circulating" phage, designated lambdaArgo phage, had at least three mutations including one in the major phage capsid (E) protein, which resulted in the change of glutamic acid to a lysine at residue 158. In the current study, we demonstrate that this single specific substitution in the E protein is sufficient to confer the "long-circulating" phenotype. The isogenic pair of phage developed in this study consisting of the long-circulating marker-rescued lambdaArgo phage, and the parental wild type phage can be used for studies of viral recognition mechanisms of the innate immune system and for the development of more effective antibacterial therapeutic phage strains.

The prospect for bacteriophage therapy in Western medicine.

Bacteriophage (phage) have been used for clinical applications since their initial discovery at the beginning of the twentieth century. However, they have never been subjected to the scrutiny--in terms of the determination of efficacy and pharmacokinetics of therapeutic agents--that is required in countries that enforce certification for marketed pharmaceuticals. There are a number of historical reasons for this deficiency, including the overshadowing discovery of the antibiotics. Nevertheless, present efforts to develop phage into reliable antibacterial agents have been substantially enhanced by knowledge gained concerning the genetics and physiology of phage in molecular detail during the past 50 years. Such efforts will be of importance given the emergence of antibiotic-resistant bacteria.

Bacteriophage SP6 is closely related to phages K1-5, K5, and K1E but encodes a tail protein very similar to that of the distantly related P22.

The lytic salmonella phage SP6 encodes a tail protein with a high degree of sequence similarity to the tail protein of the biologically unrelated lysogenic salmonella phage P22. The SP6 tail gene is flanked by an upstream region that contains a promoter and a downstream region that contains a putative Rho-independent transcription terminator, giving it a cassette or modular structure almost identical to the structure of the tail genes of coliphages K1E, K5, and K1-5. It now appears that SP6, K1-5, K5, and K1E are very closely related but have different tail fiber proteins, giving them different host specificities.

Bacteriophage therapy rescues mice bacteremic from a clinical isolate of vancomycin-resistant Enterococcus faecium.

Colonization of the gastrointestinal tract with vancomycin-resistant Enterococcus faecium (VRE) has become endemic in many hospitals and nursing homes in the United States. Such colonization predisposes the individual to VRE bacteremia and/or endocarditis, and immunocompromised patients are at particular risk for these conditions. The emergence of antibiotic-resistant bacterial strains requires the exploration of alternative antibacterial therapies, which led our group to study the ability of bacterial viruses (bacteriophages, or phages) to rescue mice with VRE bacteremia. The phage strain used in this study has lytic activity against a wide range of clinical isolates of VRE. One of these VRE strains was used to induce bacteremia in mice by intraperitoneal (i.p.) injection of 10(9) CFU. The resulting bacteremia was fatal within 48 h. A single i.p. injection of 3 x 10(8) PFU of the phage strain, administered 45 min after the bacterial challenge, was sufficient to rescue 100% of the animals. Even when treatment was delayed to the point where all animals were moribund, approximately 50% of them were rescued by a single injection of this phage preparation. The ability of this phage to rescue bacteremic mice was demonstrated to be due to the functional capabilities of the phage and not to a nonspecific immune effect. The rescue of bacteremic mice could be effected only by phage strains able to grow in vitro on the bacterial host used to infect the animals, and when such strains are heat inactivated they lose their ability to rescue the infected mice.

Frequencia da mutacao delta-mtDNA 4977 e acumulo de placas neuriticas e emaranhados neurofibrilares no giro para-hipocampal humano, no envelhecimento normal e na doenca de Alzheimer / Delta mtDNA 4977 mutational frequence and neuritic plaques and neurofibrillary tangles in human parahippocampal gyrus, in normal aging and Alzheimer's disease

A presenca da mutacao-delecao mtDNA no giro para-hipocampal humano foi investigada em 95 pacientes autopsiados de tres series de origens geograficas distintas, Alemanha, Brasil e Japao, incluindo 70 pacientes sem doencas neuropsiquiatricas e 25 pacientes portadores da doenca de Alzheimer. Somente a serie alema, caracterizada por maiores proporcoes de neuronios medios e grandes, e alta incidencia de placas neuriticas e emaranhados neurofibrilares no giro para-hipocampal, apresentou a delta-mtDNA em niveis detectaveis pela reacao de cadeia da polimerase (PCR). As series brasileira e japonesa, caracterizadas por menores proporcoes de neuronios medios e grandes e baixa incidencia de placas e emaranhados, nao apresentaram niveis detectaveis da alfa-mtDNA. A frequencia f da alfa-mtDNA foi tres vezes menor no grupo de pacientes portadores da doenca de Alzheimer (f=0,12) que no grupo controle (f=0,37) (p=0,03)...