Poliovirus

384,139views

test

00:00 / 00:00

Poliovirus

Watch later

Watch later

Lead poisoning
Hemolytic disease of the newborn
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
Autoimmune hemolytic anemia
Pyruvate kinase deficiency
Paroxysmal nocturnal hemoglobinuria
Sickle cell disease (NORD)
Hereditary spherocytosis
Aplastic anemia
Fanconi anemia
Megaloblastic anemia
Folate (Vitamin B9) deficiency
Vitamin B12 deficiency
Diamond-Blackfan anemia
Acute intermittent porphyria
Porphyria cutanea tarda
Hemophilia
Vitamin K deficiency
Bernard-Soulier syndrome
Glanzmann's thrombasthenia
Hemolytic-uremic syndrome
Thrombotic thrombocytopenic purpura
Von Willebrand disease
Disseminated intravascular coagulation
Heparin-induced thrombocytopenia
Antithrombin III deficiency
Factor V Leiden
Protein C deficiency
Protein S deficiency
Antiphospholipid syndrome
Hodgkin lymphoma
Non-Hodgkin lymphoma
Chronic leukemia
Acute leukemia
Leukemoid reaction
Myelodysplastic syndromes
Polycythemia vera (NORD)
Myelofibrosis (NORD)
Essential thrombocythemia (NORD)
Langerhans cell histiocytosis
Multiple myeloma
Monoclonal gammopathy of undetermined significance
Waldenstrom macroglobulinemia
Microcytic anemia: Pathology review
Heme synthesis disorders: Pathology review
Anticoagulants: Heparin
Anticoagulants: Warfarin
Anticoagulants: Direct factor inhibitors
Antiplatelet medications
Thrombolytics
Introduction to the immune system
Cytokines
Innate immune system
Complement system
T-cell development
B-cell development
MHC class I and MHC class II molecules
T-cell activation
B-cell activation and differentiation
Cell-mediated immunity of CD4 cells
Cell-mediated immunity of natural killer and CD8 cells
Antibody classes
Somatic hypermutation and affinity maturation
VDJ rearrangement
Contracting the immune response and peripheral tolerance
B- and T-cell memory
Anergy, exhaustion, and clonal deletion
Vaccinations
Type I hypersensitivity
Type II hypersensitivity
Type III hypersensitivity
Type IV hypersensitivity
Sepsis
Neonatal sepsis
Abscesses
Food allergy
Anaphylaxis
Rheumatic heart disease
Myasthenia gravis
Graves disease
Pemphigus vulgaris
Serum sickness
Systemic lupus erythematosus
Poststreptococcal glomerulonephritis
Graft-versus-host disease
Contact dermatitis
Transplant rejection
Cytomegalovirus infection after transplant (NORD)
Post-transplant lymphoproliferative disorders (NORD)
X-linked agammaglobulinemia
Selective immunoglobulin A deficiency
Common variable immunodeficiency
IgG subclass deficiency
Hyperimmunoglobulin E syndrome
Isolated primary immunoglobulin M deficiency
Thymic aplasia
DiGeorge syndrome
Severe combined immunodeficiency
Adenosine deaminase deficiency
Ataxia-telangiectasia
Hyper IgM syndrome
Wiskott-Aldrich syndrome
Leukocyte adhesion deficiency
Chediak-Higashi syndrome
Chronic granulomatous disease
Complement deficiency
Hereditary angioedema
Asplenia
Thymoma
Ruptured spleen
Development of the integumentary system
Skin anatomy and physiology
Hair, skin and nails
Wound healing
Vitiligo
Albinism
Acne vulgaris
Folliculitis
Rosacea
Hidradenitis suppurativa
Atopic dermatitis
Lichen planus
Pityriasis rosea
Psoriasis
Seborrhoeic dermatitis
Urticaria
Actinic keratosis
Epidermolysis bullosa
Bullous pemphigoid
Erythema multiforme
Stevens-Johnson syndrome
Pressure ulcer
Sunburn
Burns
Frostbite
Cellulitis
Erysipelas
Impetigo
Necrotizing fasciitis
Human papillomavirus
Varicella zoster virus
Poxvirus (Smallpox and Molluscum contagiosum)
Coxsackievirus
Herpes simplex virus
Candida
Malassezia (Tinea versicolor and Seborrhoeic dermatitis)
Pediculus humanus and Phthirus pubis (Lice)
Sarcoptes scabiei (Scabies)
Human herpesvirus 6 (Roseola)
Parvovirus B19
Measles virus
Rubella virus
Vascular tumors
Human herpesvirus 8 (Kaposi sarcoma)
Angiosarcomas
Skin cancer
Alopecia areata
Telogen effluvium
Onychomycosis
Development of the axial skeleton
Development of the limbs
Development of the muscular system
Skeletal system anatomy and physiology
Bone remodeling and repair
Cartilage structure and growth
Fibrous, cartilage, and synovial joints
Muscular system anatomy and physiology
Brachial plexus
Neuromuscular junction and motor unit
Sliding filament model of muscle contraction
Slow twitch and fast twitch muscle fibers
Muscle contraction
Muscle spindles and golgi tendon organs
Radial head subluxation (Nursemaid elbow)
Developmental dysplasia of the hip
Legg-Calve-Perthes disease
Slipped capital femoral epiphysis
Transient synovitis
Osgood-Schlatter disease (traction apophysitis)
Rotator cuff tear
Dislocated shoulder
Winged scapula
Thoracic outlet syndrome
Carpal tunnel syndrome
Ulnar claw
Erb-Duchenne palsy
Klumpke paralysis
Iliotibial band syndrome
Unhappy triad
Anterior cruciate ligament injury
Patellar tendon rupture
Meniscus tear
Patellofemoral pain syndrome
Sprained ankle
Achilles tendon rupture
Spondylolysis
Spondylolisthesis
Degenerative disc disease
Spinal disc herniation
Sciatica
Compartment syndrome
Rhabdomyolysis
Osteogenesis imperfecta
Craniosynostosis
Pectus excavatum
Arthrogryposis
Genu valgum
Genu varum
Pigeon toe
Flat feet
Club foot
Cleidocranial dysplasia
Achondroplasia
Osteomyelitis
Bone tumors
Osteochondroma
Chondrosarcoma
Osteoporosis
Osteomalacia and rickets
Osteopetrosis
Paget disease of bone
Osteosclerosis
Lordosis, kyphosis, and scoliosis
Osteoarthritis
Spondylosis
Spinal stenosis
Rheumatoid arthritis
Juvenile idiopathic arthritis
Gout
Calcium pyrophosphate deposition disease (pseudogout)
Psoriatic arthritis
Ankylosing spondylitis
Reactive arthritis
Spondylitis
Septic arthritis
Bursitis
Baker cyst
Muscular dystrophy
Polymyositis
Dermatomyositis
Inclusion body myopathy
Polymyalgia rheumatica
Fibromyalgia
Rhabdomyosarcoma
Lambert-Eaton myasthenic syndrome
Sjogren syndrome
Mixed connective tissue disease
Raynaud phenomenon
Scleroderma
Development of the nervous system
Nervous system anatomy and physiology
Neuron action potential
Cerebral circulation
Blood brain barrier
Cerebrospinal fluid
Cranial nerves
Ascending and descending spinal tracts
Sympathetic nervous system
Adrenergic receptors
Parasympathetic nervous system
Cholinergic receptors
Body temperature regulation (thermoregulation)
Hunger and satiety
Cerebellum
Basal ganglia: Direct and indirect pathway of movement
Memory
Sleep
Consciousness
Learning
Stress
Language
Emotion
Attention
Spina bifida
Chiari malformation
Dandy-Walker malformation
Syringomyelia
Tethered spinal cord syndrome
Aqueductal stenosis
Septo-optic dysplasia
Cerebral palsy
Spinocerebellar ataxia (NORD)
Transient ischemic attack
Ischemic stroke
Intracerebral hemorrhage
Epidural hematoma
Subdural hematoma
Subarachnoid hemorrhage
Saccular aneurysm
Arteriovenous malformation
Broca aphasia
Wernicke aphasia
Wernicke-Korsakoff syndrome
Kluver-Bucy syndrome
Concussion and traumatic brain injury
Shaken baby syndrome
Epilepsy
Febrile seizure
Early infantile epileptic encephalopathy (NORD)
Tension headache
Cluster headache
Migraine
Idiopathic intracranial hypertension
Trigeminal neuralgia
Cavernous sinus thrombosis
Alzheimer disease
Vascular dementia
Frontotemporal dementia
Lewy body dementia
Creutzfeldt-Jakob disease
Normal pressure hydrocephalus
Torticollis
Essential tremor
Restless legs syndrome
Parkinson disease
Huntington disease
Opsoclonus myoclonus syndrome (NORD)
Multiple sclerosis
Central pontine myelinolysis
Acute disseminated encephalomyelitis
Transverse myelitis
JC virus (Progressive multifocal leukoencephalopathy)
Adult brain tumors
Acoustic neuroma (schwannoma)
Pituitary adenoma
Pediatric brain tumors
Brain herniation
Brown-Sequard Syndrome
Cauda equina syndrome
Treponema pallidum (Syphilis)
Friedreich ataxia
Neurogenic bladder
Meningitis
Neonatal meningitis
Encephalitis
Brain abscess
Epidural abscess
Sturge-Weber syndrome
Tuberous sclerosis
Neurofibromatosis
von Hippel-Lindau disease
Amyotrophic lateral sclerosis
Spinal muscular atrophy
Poliovirus
Guillain-Barre syndrome
Charcot-Marie-Tooth disease
Bell palsy
Orthostatic hypotension
Horner syndrome
Congenital neurological disorders: Pathology review
Headaches: Pathology review
Seizures: Pathology review
Cerebral vascular disease: Pathology review
Traumatic brain injury: Pathology review
Spinal cord disorders: Pathology review
Dementia: Pathology review
Central nervous system infections: Pathology review
Movement disorders: Pathology review
Neuromuscular junction disorders: Pathology review
Demyelinating disorders: Pathology review
Adult brain tumors: Pathology review
Pediatric brain tumors: Pathology review
Neurocutaneous disorders: Pathology review
Cholinomimetics: Direct agonists
Cholinomimetics: Indirect agonists (anticholinesterases)
Muscarinic antagonists
Sympathomimetics: Direct agonists
Sympatholytics: Alpha-2 agonists
Adrenergic antagonists: Presynaptic
Adrenergic antagonists: Alpha blockers
Adrenergic antagonists: Beta blockers
Anticonvulsants and anxiolytics: Barbiturates
Anticonvulsants and anxiolytics: Benzodiazepines
Nonbenzodiazepine anticonvulsants

Assessments

Flashcards

0 / 18 complete

USMLE® Step 1 questions

0 / 3 complete

High Yield Notes

7 pages

Flashcards

Poliovirus

0 of 18 complete

Questions

USMLE® Step 1 style questions USMLE

0 of 3 complete

A 14-week-old girl is brought to the pediatrician for a follow-up appointment. Her parents are concerned since their neighbor’s child recently became ill and developed asymmetric weakness of the lower extremities. The patient was born in Pakistan, and her birth history was uncomplicated. During the visit, the patient is given oral droplets to prevent infection against an RNA enterovirus. This pharmaceutical agent works via which of the following mechanisms of action?  

External References

First Aid

2024

2023

2022

2021

Poliovirus p. 545

immunodeficient patients p. 116

medical importance p. 164

picornavirus p. 165

unvaccinated children p. 183

Paralysis

poliovirus p. 183

Sabin poliovirus vaccine p. 164

Vaccines p. 109

Poliovirus p. 164

Poliomyelitis p. 545

restrictive lung disease p. 694

Cerebrospinal fluid (CSF)

poliomyelitis p. 545

Headache p. 532

poliomyelitis p. 545

Nausea

polio presentation p. 545

Transcript

Watch video only

In poliomyelitis, also called polio, “polio” refers to the poliovirus, which is an enterovirus that invades the intestines, “myel” refers to the spinal cord which is affected in the disease, and -itis refers to inflammation.

So poliomyelitis is an enteroviral disease first enters the body through the intestines, but then spreads and causes nerve injury in the spinal cord.

Former US president Franklin D. Roosevelt contracted polio when he was a baby, and it left him wheelchair-bound.

Broadly speaking, the nervous system consists of two parts.

The central nervous system consists of the brain and the spinal cord.

So the peripheral nervous system includes the nerves that fan out from the central nervous system to reach the skin, muscles, and organs.

Now looking at the cross-section of the brain, there’s gray matter at the periphery of the brain. This is called the cerebral cortex and it consists of nerve cell bodies.

Just inside the gray matter of the brain, is the white matter, and it consists of nerve axons.

In contrast, if you look at the cross-section of the spinal cord, the white matter is on the outside and the gray matter is on the inside, and overall it kinda looks like a butterfly.

If we draw a horizontal line through the spinal cord, the front half is the anterior or ventral half, and the back half is the posterior or dorsal half.

And the butterfly wings are sometimes referred to as horns; so we have two dorsal horns that contain cell bodies for sensory neurons and two ventral horns that contain cell bodies for motor neurons.

So for example, if you step on a lego in your living room, the sensation of discomfort is carried from the nerves in your foot, through the peripheral nervous system to reach the dorsal horn in the spinal cord.

It then travels up the spinal cord to the brain, letting you know that there’s tissue damage.

In response, your brain sends a message through the upper motor neurons, which are part of the cerebral cortex, and down the spinal cord to a lower motor neuron which is located in the anterior horn of the spinal cord.

From there, the signal finally gets delivered to the leg muscles and allows you to lift your foot.

In addition to sending signals from the brain, these lower motor neurons also release trophic or growth factors that promote muscle growth in the muscle that they innervate.

Polio is a viral infection caused by poliovirus which is a single-stranded RNA virus that’s protected by a capsid, which is a protein coat.

Polio mainly affects children under the age of 5 and it’s spread by fecal-oral transmission, which means that the virus usually enters the body through contaminated food and water that goes in the mouth.

It’s also transmitted when an infected person sneezes or coughs, which spreads thousands of virus-containing droplets into the local area.

Once the virus enters the body, it binds to mucosal cells of the oropharynx and small intestine, and gets inside those cells, and then releases its RNA.

The viral RNA uses the cell’s RNA polymerase enzyme to make copies of itself, and then the new RNA copies hijack the ribosomes that normally make proteins for the cell, and forces the ribosomes to make viral proteins instead.

The viral protein and RNA self-assemble into lots of new polioviruses, and within days, they cause the mucosal cell to lyse, releasing the newly formed viruses which make their way to nearby lymph nodes and eventually into the bloodstream.

Poliovirus prefers to infect motor nerves, so oftentimes it will leave a blood vessel and get into the interstitial tissue of muscle tissue.

From there, poliovirus invades the motor neuron and travels retrograde - meaning backwards up through the axon - to the anterior horn of the spinal cord.

Infected motor neurons attract immune cells like neutrophils and macrophages which cause inflammation and damage to the spinal cord.

As infected motor neurons die, the muscles of the trunk and limbs no longer receive signals from the brain or trophic factors which causes the muscles to start to atrophy and become weak.

On rare occasions, poliovirus can cause bulbar polio, which is when it affects a part of the brain stem that has motor nerves involved in speaking and swallowing.

This part of the brain stem also sends motor nerves to the diaphragm and so if they get damaged, it can impair breathing.

Summary

Poliovirus is a single-stranded RNA virus, known to cause poliomyelitis. It is transmitted through fecal-oral transmission or by aerosol droplets, and then replicates in the small intestine and oropharynx before it spreads to the central nervous system and causes nerve injury. Symptoms include high fevers, intense muscle pain from spasms and weakness, loss of muscle reflexes, and eventually paralysis. Diagnosis is done by the detection of the poliovirus from a stool or throat, or by analysis of the cerebrospinal fluid. There is no cure for polio, but it can be prevented by polio vaccines.