A passenger virus is a

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

that is frequently found in samples from diseased tissue, such as

tumour A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

s, but is not a contributing factor in causing the

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

Experimental demonstration of passenger status

Proving that a virus has no causative role can be difficult. Although none of the following signs is definitive, evidence that a virus found in diseased tissue might be passenger only rather than a causative agent includes: *injection of the virus into healthy animals without causing disease; *the absence of the virus at the earliest stages of the disease; *curing the viral infection using

antiviral drug Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do n ...

s or

vaccination Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating ...

with no effect on the course of the disease.

Examples

A well-established example is lactate dehydrogenase virus, which is often found in mouse tumours.

GB virus C GB virus C (GBV-C), formerly known as hepatitis G virus (HGV) and also known as human pegivirus – HPgV is a virus in the family ''Flaviviridae'' and a member of the ''Pegivirus'', is known to infect humans, but is not known to cause human dise ...

and

Chandipura virus ''Chandipura vesiculovirus'' (CHPV) is a member of the ''Rhabdoviridae'' family that is associated with an encephalitic illness in humans. It was first identified in 1965 after isolation from the blood of two patients from Chandipura village in ...

are possible examples in humans. It has also been suggested that a virus related to

Alcelaphine herpesvirus 1 The subfamily Alcelaphinae or tribe Alcelaphini of the family Bovidae contains wildebeest, hartebeest, bonteboks, and several similar species. Depending on the classification, there are 6–10 species placed in four genera, although ''Beatragus'' ...

is a passenger virus that, unlike AHV1 itself, does not cause

bovine malignant catarrhal fever Bovine malignant catarrhal fever (BMCF) is a fatal lymphoproliferative disease caused by a group of ruminant gamma herpes viruses including ''Alcelaphine gammaherpesvirus 1'' (AlHV-1) and ''Ovine gammaherpesvirus 2'' (OvHV-2) These viruses cause ...

. The discredited

Duesberg hypothesis The Duesberg hypothesis is the claim that AIDS is not caused by HIV, but, instead, that AIDS is caused by noninfectious factors such as recreational and pharmaceutical drug use and that HIV is merely a harmless passenger virus. The hypothesis wa ...

posits that

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

is a passenger virus in the

etiology Etiology (pronounced ; alternatively: aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek (''aitiología'') "giving a reason for" (, ''aitía'', "cause"); and ('' -logía''). More completely, e ...

AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual m ...

References

{{reflist Virology