Polyoma Virus

Question 1

Micro details of Polyoma virus

Answer 1

• family papovaviridae
  subfamily - papilloma
• Circular dsDNA, very small
  non-enveloped icosahedral capsid

Question 2

How are polyoma viruses pathogenic?

Answer 2

• transform non-permissive cells and lead to tumor formation
• use large and small T antigen to make immortalized cells then the virus uses middle and small T antigen to transform non-permissive cells

Question 3

What are the two types of polyoma virus

Answer 3

BK and JC

• 50% of 3-4 yos seropositive for BK
• 50% of 10-14 yr olds seropositive for JC
• infections in healthy kids are unapparent
• they are ubiquitious but aren’t oncogenic in humans

Question 4

Who usually gets diseases w/ polyoma virus?

Answer 4

1. ICP like transplant patients and AIDs

Question 5

What must polyoma viruses do to be as pathogenic as they can be?

Answer 5

• they have overlapping splicing regions to increase the number of proteins they can make to infect cells
• have many types of early T proteins

Question 6

How do JC and BK viruses infect humans?

Answer 6

1. inoculate in respiratory tract
2. multiply here and lead to primary viremia and multiply in kidneys leading to transient secondary viremia
3. immunocompetent pts - have latent viruses in kidneys
4. ICPS - have reactivation of BK and JC virus
   BK - stays in urinary tract and may cause hemorrhagic cystitis
   JC - goes to CNS and causes PML, death w/in 3-6 months, reactivated virus infects and lyses oligodendrocytes

Question 7

Dx of JC?

Answer 7

cell culture is not practical

• detect white matter lesion by MRI
• PCR amplification of JC DNA from infected brain or spinal fluid

Question 8

Rx for PML

Answer 8

• adjust immunosuppression in transplant pts

- adjust HAART in AIDS patients