Role of Simian Vacuolating Virus-40 (SV-40) in Causing Cancer/Tumors

The Simian vacuolating virus-40 (SV-40) is a polyoma virus. The SV-40 is a DNA virus that has the potential to cause tumors. Simian vacuolating virus-40 is believed to slash/suppress the transcriptional properties of tumor-suppressing p53 gene in human beings through its large T-antigen (SV-40 large T-antigen) as well as small T-antigen (SV-40 small T-antigen). It has been genetically established that SV-40 large T-antigen is the major protein involved in neoplastic process. The SV-40 large T-antigen predominantly exerts its effect through deregulation of tumor-suppressing p53 gene, which is responsible for initiating regulated cell death (apoptosis). The regulated cell death or apoptosis is a natural phenomenon that is must for maintaining shape and size of our body organs and tissues. The p53 gene is the most often mutated gene in human cancers. Due to its tumor suppressor role the p53 gene is invariably called the guardian of human genome. The p53 protein present in the cells, plays a major role in the regulation of normal cell cycle, differentiation of cells and cell death. The p53 gene also takes care of DNA repair, aging process and formation of blood vessels. It provides switching mechanism for activation and deactivation of transcription of its target genes by binding to the corresponding DNA sequences in the nuclei of cells. The cell cycle is arrested normally when a cell is damaged. Mutations caused by SV-40 virus in p53 gene would contribute to uncontrolled cellular proliferation, leading to a tumor. It has very well been reported in the medical literature that SV-40 is associated with brain tumors, malignant mesothelioma, non-Hodgkin lymphoma and bone cancers.


Immunohistochemical (IHC) testing is required to detect and demonstrate the viral infection in tumor tissue/biopsy. The immunohistochemical detection of simian vacuolating virus-40 (SV-40) could be culminated, using anti-simian vacuolating virus-40 (anti-SV-40) antibodies. The IHC testing on formalin fixed, paraffin embedded tissues has an advantage over immunofluorescence testing that one would have the convenience of archiving IHC stained slides for future reference. The worldwide availability of anti-simian vacuolating virus-40 (anti-SV-40) antibodies has given a boost to the research in this field.

Amoebiasis: Bowel amoebiasis and spread of infection to liver and lungs

The organism that causes amoebiasis is a unicellular parasite called Entamoeba histolytica. A variety of clinical presentations are seen. Though the disease is not a major health problem but in serious forms of amoebiasis, significant morbidity and mortality is unavoidable. We may have asymptomatic carriers of amoebic infection. On the other hand Entamoeba histolytica infection may result in fulminant dysentery with fever, diarrhoea, bleeding and even perforation of intestine. The organism can be identified in wet slide preparation of stool specimen obtained from infected patient.

The infection is transmitted by the faeco-oral route. The infection can be an asymptomatic one, that is, the victim could be in good health in-spite of harboring the Entamoeba histolytica infection. In severe cases of infection, Entamoeba histolytica can result in full-fledged frank dysentery along with colonic ulceration. Uncommonly, Entamoeba histolytica can invade organs other than large intestine. Liver is the second common site followed by lungs. The brain, genitals and the skin are other possible sites if infection by the amoeba. The majority of patients do not develop frank-dysentery, i.e. they do not develop diarrhoea with blood or mucus. Vague symptoms, such as discomfort in the tummy, irregularity of bowels, constipation, diarrhoea, griping and tenesmus occur in various combinations. In some cases, low grade fever, loss of weight, pallor, generalized non-specific aches and pains are common. The patient usually carries on his day-to day duties with sub-optimum health and efficiency.

The diagnosis of asymptomatic bowel amoebic infection can be established through repeated fresh stool microscopic examination. The sigmoidoscopic examination of ulcerative lesions of colon and microscopic examination of direct smears obtained from the ulcers would further confirm the diagnosis of amoebic ulcers. Invasion of liver by Entamoeba histolytica is the second commonest form of amoebiasis. The onset is usually insidious but an exceptionally rapid course can be seen during endemics of bowel amoebiasis. The presenting symptoms of liver amoebiasis are pain in the upper right quadrant of tummy, or fever or both. The presence of jaundice is very rare in patients with liver amoebiasis. Fever of uncertain origin is a common problem in many developing countries. One of the causes of the fever of uncertain origin could be amoebic infection of the liver.

The diagnosis of amoebic infection of the lungs and brain requires a high degree of expertise on the part of physician/clinician. The amoebic infection of brain is usually diagnosed at the operation table. Amoebic ulceration of skin is not very rare. Sophisticated techniques like serology and radio-isotopic scan can be of great help in establishing the diagnosis of amoebic abscess of liver, lung or brain. The treatment of amoebiasis is highly effective once a correct diagnosis has been made. Eradication or prevention of amoebiasis in any locality can be achieved only if there are optimum ways of sewage disposal and personal hygiene.