Host nutritional status: the neglected virulence factor.

The emergence of new infectious diseases and old diseases with new pathogenic properties is a burgeoning worldwide problem. Severe acute respiratory syndrome (SARS) and acquired immune deficiency syndrome (AIDS) are just two of the most widely reported recent emerging infectious diseases. What are the factors that contribute to the rapid evolution of viral species? Various hypotheses have been proposed, all involving opportunities for virus spread (for example, agricultural practices, climate changes, rainforest clearing or air travel). However, the nutritional status of the host, until recently, has not been considered a contributing factor to the emergence of infectious disease. In this review, we show that host nutritional status can influence not only the host response to the pathogen, but can also influence the genetic make-up of the viral genome. This latter finding markedly changes our concept of host-pathogen interactions and creates a new paradigm for the study of such phenomena.

The antibody response to influenza vaccination is not impaired in type 2 diabetics.

BACKGROUND: Diabetics are considered to be at high risk for complications from influenza infection and type 2 diabetes is a significant comorbidity of obesity. Obesity is an independent risk factor for complications from infection with influenza. Annual vaccination is considered the best strategy for protecting against influenza infection and it's complications. Our previous study reported intact antibody responses 30 days post vaccination in an obese population. This study was designed to determine the antibody response to influenza vaccination in type 2 diabetics. METHODS: Subjects enrolled were 18 or older without immunosuppressive diseases or taking immunosuppressive medications. A pre-vaccination blood draw was taken at time of enrollment, the subjects received the influenza vaccine and returned 28-32 days later for a post-vaccination blood draw. Height and weight were also obtained at the first visit and BMI was calculated. Antibody levels to the vaccine were determined by both ELISA and hemagglutination inhibition (HAI) assays. RESULTS: As reported in our previous work, obesity positively correlates with the influenza antibody response (p=0.02), while age was negatively correlated with antibody response (p<0.001). In both year 1 and year 2 of our study there was no significant difference in the percentage of the type 2 diabetic subjects classified as seroprotected or a responder to the influenza vaccine compared to the non-diabetic subjects. CONCLUSIONS: These data are important because they demonstrate that diabetics, considered a high risk group during influenza season, are able to mount an antibody response to influenza vaccination that may protect them from influenza infection.

Overweight and obese adult humans have a defective cellular immune response to pandemic H1N1 influenza A virus.

OBJECTIVE: Obese adults have a greater risk of morbidity and mortality from infection with pandemic H1N1 influenza A virus (pH1N1). The objective of the present study was to elucidate the specific mechanisms by which obesity and overweight impact the cellular immune response to pH1N1. DESIGN AND METHODS: Peripheral blood mononuclear cells from healthy weight, overweight, and obese individuals were stimulated ex vivo with live pH1N1 and then markers of activation and function were measured using flow cytometry and cytokine secretion was measured using cytometric bead array assays. RESULTS: CD4(+) and CD8(+) T cells from overweight and obese individuals expressed lower levels of CD69, CD28, CD40 ligand, and interleukin-12 receptor, as well as, produced lower levels of interferon-γ and granzyme B, compared with healthy weight individuals, suggesting deficiencies in activation and function are indicated. Dendritic cells from the three groups expressed similar levels of major histocompatibility complex-II, CD40, CD80, and CD86, as well as, produced similar levels of interleukin-12. CONCLUSIONS: The defects in CD4(+) and CD8(+) T cells may contribute to the increased morbidity and mortality from pH1N1 in obese individuals. These data also provide evidence that both overweight and obesity cause impairments in immune function.

Functional markers of selenium status: UK Food Standards Agency workshop report.

The workshop was organised to discuss the validity and limitations of existing functional markers of Se status in human subjects and to identify future research priorities in this area. Studies presented as part of this workshop investigated: the bioavailability of Se from different dietary sources; potential functional markers of Se status; individual variation in response to Se; the effect of marginal Se status on immune function. The workshop highlighted the need to define the relationship between functional markers of Se status and health outcomes.

Cytomegalovirus viremia, mortality, and end-organ disease among patients with AIDS receiving potent antiretroviral therapies.

OBJECTIVE: To determine the association of cytomegalovirus (CMV) viremia with CMV disease and death in patients with AIDS. DESIGN AND SETTING: Prospective, observational cohort study conducted at a university hospital. METHODS: A cohort of 190 subjects with AIDS who were CMV seropositive and had no history or evidence of CMV disease were longitudinally evaluated for signs and symptoms of CMV disease and CMV viremia with plasma CMV DNA polymerase chain reaction (PCR) and whole blood CMV hybrid capture. RESULTS: A total of 187 subjects had at least 1 study visit following entry. At baseline, the median CD4 cell count and plasma HIV RNA level were 110/microL (range = 3-620/microL) and 47,973 copies/mL (<30- >750,000 copies/mL), respectively. Highly active antiretroviral therapy (HAART) use increased from 87.5% during the 1st study year to 98.5% by the end of the study. During a median follow-up of 334 days, 16% (30) of the subjects died and 2 (6%) developed CMV disease. No deaths were attributable to CMV disease; 4 subjects who died developed CMV prior to death. Baseline HIV viral load and final CD4 cell count were significantly and independently associated with mortality. Detectable plasma CMV DNA PCR was an independent predictor of death even after adjusting for HIV RNA level and CD4 cell count prior to death (P = 0.038). In contrast, whole blood CMV hybrid capture did not predict mortality. The CMV assays neither collectively nor individually were found to be associated with the few cases of CMV disease. CONCLUSIONS: In patients with AIDS and seropositive for CMV, detection of CMV viremia with plasma CMV DNA PCR was predictive of death and provided additional prognostic information on the risk of all cause-mortality beyond that obtained with CD4 cell count and HIV viral load testing alone. Detection of CMV viremia by plasma with CMV DNA PCR in patients with AIDS, particularly those with low CD4 cell counts, provides additional rationale for optimization of antiretroviral therapy and consideration for preemptive anti-CMV therapy.

Selenium deficiency and viral infection.

The discovery that the juvenile cardiomyopathy known as Keshan disease likely has a dual etiology that involves both a nutritional deficiency of the essential trace mineral selenium (Se) as well as an infection with an enterovirus provided the impetus for additional studies of relationships between nutrition and viral infection. An amyocarditic strain of coxsackievirus B3, CVB3/0, converted to virulence when it was inoculated into Se-deficient mice. This conversion was accompanied by changes in the genetic structure of the virus so that its genome closely resembled that of other known virulent CVB3 strains. Similar alterations in virulence and genomic composition of CVB3/0 could be observed in mice fed normal diets but genetically deprived of the antioxidant selenoenzyme glutathione peroxidase (knockout mice). More recent research has shown that a mild strain of influenza virus, influenza A/Bangkok/1/79, also exhibits increased virulence when given to Se-deficient mice. This increased virulence is accompanied by multiple changes in the viral genome in a segment previously thought to be relatively stable. Epidemic neuropathy in Cuba has features that suggest a combined nutritional/viral etiology. Further research, both basic and applied, is needed to assess properly the possible role of malnutrition in contributing to the emergence of novel viral diseases.

Caracterización genómica de la cepa cubana de efecto citopático ligero / Genomic characterization of the Cuban strain of light cytopathic effect

Durante la epidemia de neuropatía ocurrida en Cuba en los años 1992/1994 se aislaron del líquido cefalorraquídeo de pacientes agentes virales relacionados antigénicamente con los virus Coxsackie. Para establecer una función de estos virus en la etiopatogenia de la enfermedad se seleccionaron las cepas 47/93 IPK identificada como Coxsackie A9 y la cepa 44/93 IPK de efecto citopático ligero (ECP-L) y se realizó un estudio de sus características antigénicas mediante Western Blot. Se comprobó la relación antigénica entre ambas cepas y se demostró la ausencia de proteínas estructurales en su forma nativa en los agentes de ECP-L. A partir de estos resultados se plantea la posibilidad de que la persistencia sea un mecanismo por el cual estos virus participen en la etiopatogenia de la neuropatía epidémica en Cuba