Cameron K. Tebbi

Several etiologic factors for the development of acute leukemias have been suggested; however, none is applicable to all cases. We isolated a certain mycovirus-containing Aspergillus flavus (MCAF) from the home of a patient with acute lymphoblastic leukemia. Repeated electron microscopic evaluations proved the existence of mycovirus in this organism. According to chemical analysis, this organism does not produce any aflatoxin, possibly due to its infestation with mycoviruses. We reported that using the ELISA technique, forty pediatric patients with acute lymphoblastic leukemia (ALL) uniformly had antibodies to the products of MCAF. In contrast, three separate groups of controls, consisting of normal blood donors, individuals with solid tumors, and patients with sickle cell disease, were negative. In vitro exposure of mononuclear blood cells from patients with ALL, in full remission, to the products of MCAF induced redevelopment of cell surface phenotypes and genetic markers characteristic of ALL. The controls were negative. The incubation of normal and ALL cell lines with the products of MCAF resulted in significant cellular apoptosis, changes in the cell cycle, and the downregulation of transcription factors, including PAX-5 and Ikaros (75 and 55 kDa). Fungi are widespread in nature, and many contain mycoviruses. Normally, an individual inhales 1 to 10 fungal spores per minute, while farmers can inhale up to 75,000 spores per minute. It is known that farmers and foresters, who are more exposed to fungi, have a higher rate of acute leukemia. In contrast, asthmatics, most of whom are allergic to fungal agents, and individuals working in office settings have a lower rate. One of the theories for the development of acute leukemia suggests a genetic predisposition followed by exposure to an infectious agent. With the above findings, we propose that mycovirus-containing Aspergillus flavus may have an etiological role in leukemogenesis in immune-depressed and genetically susceptible individuals.

Several etiologic factors for the development of acute leukemias have been suggested, however, none is applicable to all cases. We have isolated a certain mycovirus-containing Aspergillus flavus (MCAF) from the home of a patient with acute lymphoblastic leukemia. Repeated electron microscopic evaluations proved the existence of mycovirus in this organism. By chemical analysis, this organism does not produce any aflatoxin, which may be due to its infestation with mycoviruses. We have reported that using the ELISA technique, forty pediatric patients with acute lymphoblastic leukemia (ALL) uniformly had antibodies to the products of MCAF. In contrast, three separate groups of controls, consisting of normal blood donors, individuals with solid tumors, and patients with sickle cell disease, were negative. In vitro exposure of mononuclear blood cells from patients with ALL, in full remission, to the products of MCAF induced redevelopment of cell surface phenotypes and genetic markers characteristic of ALL. Controls were negative. Incubation of normal and ALL cell lines with the products of MCAF resulted in significant cellular apoptosis, changes in the cell cycle, and downregulation of transcription factors, including PAX-5 and Ikaros (75 and 55 kDa). Fungi are widespread in nature, and many contain mycoviruses. Normally, an individual inhales 1 to 10 fungal spores per minute, while farmers can inhale up to 75000 spores per minute. It is known that farmers and foresters, who are more exposed to fungi, have a higher rate of acute leukemia. In contrast, asthmatics, most of whom are allergic to fungal agents, and individuals working in office settings have a lower rate. One of the theories for the development of acute leukemia suggests a genetic predisposition followed by exposure to an infectious agent. With the above findings, we propose that mycovirus-containing Aspergillus flavus may have an etiological role in leukemogenesis in immune-depressed and genetically susceptible individuals.

Transcription factors control genes to maintain normal hemopoiesis, and dysregulation of some factors can lead to acute lymphoblastic leukemia (ALL). Mycoviruses are known to alter the genetics of their fungal host. The present study evaluates the effects of the products of a mycovirus-containing Aspergillus flavus (MCAF), isolated from the home of a patient with ALL, on certain transcription factors of normal and ALL cell lines. Our published studies have shown that ALL patients have antibodies to MCAF, and that exposure of the mononuclear leukocytes of patients in complete remission to its products, unlike controls, results in the re-development of genetic and cell surface phenotypes characteristic of ALL. For the present study, normal, pre-B, and B-cell leukemia cell lines were exposed to the culture of MCAF. Pre- and post-exposure levels of PAX5, Ikaros, and NF-κB were assessed. Exposure to MCAF resulted in apoptosis, cell cycle changes, and complete downregulation of all transcription factors in normal cell lines. In acute leukemia cell lines, cellular apoptosis and alterations in the cell cycle were also noted; however, while there was downregulation of all tested transcription factors, residual levels were retained. The noted alterations in the transcription factors caused by MCAF are novel findings. The possible role of MCAF in leukemogenesis needs to be further investigated. Mycovirus-containing Aspergillus flavus was initially isolated from a leukemia patient’s home. Our prior published studies have illuminated intriguing associations of this organism with leukemia. Unlike controls, patients diagnosed with acute lymphoblastic leukemia (ALL) harbor antibodies to this organism. Furthermore, the exposure of mononuclear cells from patients with ALL in complete remission to the products of this organism reproduced genetic and cell phenotypes characteristic of ALL. These findings underscore the potential role of environmental factors in leukemogenesis and hint at novel avenues for therapeutic intervention and preventive strategies.

Transcription factors bind specific DNA motifs to regulate the expression of target genes in order to maintain normal hematopoiesis

Certain viruses have been found to induce diverse biological pathways to carcinogenesis, evidenced by the presence of viral gene products in some tumors. Despite the fact that many fungal agents contain mycoviruses, until recently, their possible direct effects on human health, including carcinogenesis and leukemogenesis, had not been explored. In this regard, most studies of fungal agents have rightly concentrated on their mycotoxin formation and effects. Recently, the direct role of yeasts and fungi in the etiology of cancers, including leukemia, have been investigated. While greater attention has been placed on the carcinogenic effects of Candida, the role of filamentous fungi in carcinogenesis has also been explored. Recent findings from studies using the enzyme-linked immunosorbent assay (ELISA) technique indicate that the plasma of patients with acute lymphoblastic leukemia (ALL) uniformly contains antibodies for a certain mycovirus-containing Aspergillus flavus, while controls are negative. The exposure of mononuclear leukocytes from patients with ALL in full remission, and long-term survivors, to the product of this organism was reported to result in the re-development of typical genetics and cell surface phenotypes characteristic of active ALL. Mycoviruses are known to be able to significantly alter the biological characteristics and functions of their host. The possible carcinogenic and leukemogenic role of mycoviruses, with and without their host, needs to be further investigated.

Sickle cell disease and its variants constitute the most common inherited blood disorders affecting millions of individuals worldwide. Significant information regarding the nature of the genetic mutations and modifier genes that result in increased or decreased severity of the disease are available. In recent years, detailed data regarding molecular genetics, pathophysiology, mechanisms for the development of symptoms and side effects of sickle cell disease have been published. The relationship of physiological changes, cellular interactions, coexisting coagulation disorders, effects of association with other genetic disorders and a number of intervening factors have been explored. New techniques for pre-conception, prenatal, in utero, and neonatal screening are available. Means for prediction of the severity of the disease, clinical course of the disorder, and prevention of some of its major complications have been developed. The effects of psychosocial and environmental factors have been explored. Various therapeutic strategies including bone marrow and stem cell transplantation are currently employed in the treatment of patients with sickle cell disease. Recent progress in understanding the molecular pathways controlling mammalian erythropoiesis and globin switching, as well as advances in genome engineering, particularly the gene-editing techniques, have opened a venue for genetic-based treatment of the disease. Currently, sickle cell disease is often associated with a high rate of complications and mortality. The development of new pharmacological agents, methods for gene therapy, and alterations and modification of the coexisting genetic factors and modifiers for treatment of the disease are encouraging.

Acute leukemias constitute some of the most common malignant disorders. Despite significant progress made in the treatment of these disorders, their etiology remains unknown. A large and diverse group of genetic and environmental variables have been proposed. The role of a variety of factors, including pre-existing and acquired genetic mutations, exposure to radiation and various chemicals during preconception, pregnancy and throughout life, have been explored. The effects of inherited genetic variations and disorders, pre-existing diseases, infectious agents, hobbies, occupations, prior treatments, and a host of other factors have been proposed, but none is universally applicable to all cases. Variation in the incidence and prognosis based on the age, sex, race, type of the disease, geographic area of residence and other factors are intriguing but remain unexplained. Advances in genomic profiling, including genome-wide gene expression, DNA copy number and single nucleotide polymorphism (SNP) genotype, may shed some light on the role of genetics in these disparities. Separate two-hit hypotheses for the development of acute myeloblastic and lymphoblastic leukemia have been proposed. The latter combines genetics and infection factors resulting in leukemogenesis. A number of pre- and post-natal environmental conditions and exposure to infections, including a mycovirus infected Aspergillus flavus, have been suggested. The exact nature, timing, sequence of the events and mechanisms resulting in the occurrence of leukemia requires further investigations. This review summarizes some of the above factors in acute lymphoblastic and myeloblastic leukemias and the direction for future research on the etiology of these disorders.

Acute lymphoblastic leukemia (ALL) is the most common cancer in children and is also seen in adults. Currently, no plasma-based test for the detection of ALL is available. We have cultured the home of a patient with ALL and isolated a mycovirus containing Aspergillus flavus. This culture was subjected to electron microscopy, purification, and mass spectrometry. Using enzyme-linked immunosorbent assay technique, plasma of patients with ALL and long-term survivors of this disease were tested for antibodies, utilizing supernatant of the culture of this organism. The results were compared with 3 groups of controls, including healthy individuals, patients with sickle cell disease, and solid tumors. Using electron microscopy, the isolated A. flavus contained mycovirus particles. In chemical analysis, this organism did not produce any aflatoxin. Using an enzyme-linked immunosorbent assay technique, the supernatant of the culture of the mycovirus containing A. flavus could differentiate ALL patients from each group of controls (P<0.001). These studies provide a new technique for the detection of ALL and may add information for future research regarding leukemogenesis.