USMLE – viruses Phloston.

USMLE – viruses Phloston

RNA viruses

RNA viruses Icosahedral or helical nucleocapsids

RNA viruses Icosahedral or helical nucleocapsids
Icosahedral are either enveloped or non-enveloped. Helicals are always enveloped.

Icosahedral are either enveloped or non-enveloped. Helicals are always enveloped. For icosahedral, non-enveloped viruses, you’ve got SS(+) non-segmented and DS-segmented.

Icosahedral are either enveloped or non-enveloped. Helicals are always enveloped. For icosahedral, non-enveloped viruses, you’ve got SS(+) non-segmented and DS-segmented. SS(+) non-segmented, non-enveloped icosahedral viruses are split into picornaviridae and caliciviridae.

Icosahedral are either enveloped or non-enveloped. Helicals are always enveloped. For icosahedral, non-enveloped viruses, you’ve got SS(+) non-segmented and DS-segmented. SS(+) non-segmented, non-enveloped icosahedral viruses are split into picornaviridae and caliciviridae. Picornaviridae are split into rhinovirus (on its own) and the enteroviruses.

RNA viruses The enteroviruses comprise polio, HepA, coxsackie and echovirus.

RNA viruses The enteroviruses comprise polio, HepA, coxsackie and echovirus. For polio, know anterior horns, superior gluteal nerve palsy (trendelenburg gait). Contraction of the virus is THROUGH INGESTION (exceedingly high-yield). Sabin (oral) is the live-vaccine. Salk (killed) is the IM/IV vaccine.

RNA viruses The enteroviruses comprise polio, HepA, coxsackie and echovirus. For polio, know anterior horns, superior gluteal nerve palsy (trendelenburg gait). Contraction of the virus is THROUGH INGESTION (exceedingly high-yield). Sabin (oral) is the live-vaccine. Salk (killed) is the IM/IV vaccine. HepA  Asymptomatic (high-yield), shortest incubation of the Heps (2-6 wks); killed vaccine

RNA viruses coxsackieA  herpangina (if instead herpes they’ll imply Cowdry bodies via mention of intranuclear inclusions), hand-foot-mouth disease

RNA viruses coxsackieA  herpangina (if instead herpes they’ll imply Cowdry bodies via mention of intranuclear inclusions), hand-foot-mouth disease coxsackie-B most common cause of viral myocarditis; DIRECT-VIRAL DAMAGE (NOT type-II HS, like rheumatic heart disease); DCM

RNA viruses coxsackieA  herpangina (if instead herpes they’ll imply Cowdry bodies via mention of intranuclear inclusions), hand-foot-mouth disease coxsackie-B most common cause of viral myocarditis; DIRECT-VIRAL DAMAGE (NOT type-II HS, like rheumatic heart disease); DCM echovirus  meningitis; they’ll tell you kid’s got meningitis from RNA virus and then ask you for the structure (i.e. non-enveloped, ssRNA virus)

RNA viruses Rhinovirus  most common cause of the common cold (high-% question); contraction occurs via ICAM-1 (CD54)  know that. Sometimes they’ll ask you for the picornavirus that’s respiratory-contracted.

RNA viruses Rhinovirus  most common cause of the common cold (high-% question); contraction occurs via ICAM-1 (CD54)  know that. Sometimes they’ll ask you for the picornavirus that’s respiratory-contracted. For caliciviridae, know calicivirus (Norwalk virus) and HepE. The catch is that HepE has recently been reclassified under hepeviridae, so if the latter shows up, it’s correct over caliciviridae, but remember both (just do it; I’ve seen both in practice questions).

RNA viruses USMLE likes Norwalk virus for cruise ships (anything where a lot of people in close contact come down with a gastroenteritis).

RNA viruses USMLE likes Norwalk virus for cruise ships (anything where a lot of people in close contact come down with a gastroenteritis). For HepE, you’ve just gotta remember pregnant women (highest yield), Asia > USA (particularly Tibet), and of course it’s enteric.

RNA viruses As we said before, icosahedral, non-enveloped RNA viruses are either SS(+)-non-segmented or DS-segmented. For DS-segmented, all you need to remember is the reoviridae.

RNA viruses As we said before, icosahedral, non-enveloped RNA viruses are either SS(+)-non-segmented or DS-segmented. For DS-segmented, all you need to remember is the reoviridae. Reoviridae  rotavirus and reovirus (coltivirus)

RNA viruses Rotavirus is most common cause of viral enteritis in young children (exceedingly high-yield); USMLE wants you to know it is HIGHLY SEGMENTED [10] (like influenza virus [8]) and therefore can undergo REASSORTMENT. They’ll ask you for the virus that can undergo genetic modulation similar to influenza.

RNA viruses Coltivirus (reovirus) causes Colorado Tick fever. I’ve never encountered a question on this. But I would be aware of the viral structure regardless.

RNA viruses The icosahedral enveloped viruses are SS(+)-non-segmented and SS(+) diploid. (deltavirus used to be in this category but has recently been moved to helical)

RNA viruses The icosahedral enveloped viruses are SS(+)-non-segmented and SS(+) diploid. (deltavirus used to be in this category but has recently been moved to helical) SS(+)-non-segmented are togaviridae and flaviviridae

RNA viruses The icosahedral enveloped viruses are SS(+)-non-segmented and SS(+) diploid. (deltavirus used to be in this category but has recently been moved to helical) SS(+)-non-segmented are togaviridae and flaviviridae Togaviridae are alpha virus (equine encephalitides) and rubivirus (rubella)

RNA viruses The icosahedral enveloped viruses are SS(+)-non-segmented and SS(+) diploid. (deltavirus used to be in this category but has recently been moved to helical) SS(+)-non-segmented are togaviridae and flaviviridae Togaviridae are alpha virus (equine encephalitides) and rubivirus (rubella) Flaviviridae are HepC, West Nile, Yellow/Dengue fevers, Japanese encephalitis

RNA viruses For the equine encephalitides, there’s EEE, WEE and VEE for Eastern, Western and Venezuelan equine encephalitis, respectively.

RNA viruses For the equine encephalitides, there’s EEE, WEE and VEE for Eastern, Western and Venezuelan equine encephalitis, respectively. All you need to know for these are that they cause CNS effects and are associated with horses. Any mention of horses  alphavirus; know the structure.

RNA viruses For the equine encephalitides, there’s EEE, WEE and VEE for Eastern, Western and Venezuelan equine encephalitis, respectively. All you need to know for these are that they cause CNS effects and are associated with horses. Any mention of horses  alphavirus; know the structure. For rubella, know that it causes post-auricular or sub-occipital lymph node tenderness. That will be the give-away. It also causes a THREE-DAY rash.

RNA viruses For HepC, be aware that it has the longest incubation period (in contrast to HepA, which has the shortest).

RNA viruses For HepC, be aware that it has the longest incubation period (in contrast to HepA, which has the shortest). Histologically, HepC will cause a nodular or clumpy appearance; HepB, in contrast, will cause a ground-glass appearance. I’ve seen a question that mentioned an IV drug-user, and then they showed the liver histology, and the answer was HepB, not HepC, and it was strictly because it had a ground-glass appearance. HepC will be nodular or clumpy, not ground-glass, despite HepC being more common in IV drug-users.

RNA viruses You treat HepC with pegylated interferon-alpha and ribavirin. Regulater interferon-alpha is Tx for HepB, not C. If they list pegylated interferon-alpha and regular interferon-alpha as answer choices to the same question, if it’s pegylated, it’s HepC, not B; if it’s regular, it’s HepB Tx.

RNA viruses You treat HepC with pegylated interferon-alpha and ribavirin. Regulater interferon-alpha is Tx for HepB, not C. If they list pegylated interferon-alpha and regular interferon-alpha as answer choices to the same question, if it’s pegylated, it’s HepC, not B; if it’s regular, it’s HepB Tx. HepC is transmitted via blood. That means, it is NOT TRANSMISSIBLE BY SEX. Obviously if there’s menstruation, there’s a risk, but for the purpose of the USMLE, HepB is transmissible by sex, but HepC is not.

RNA viruses Like HepB, HepC is transmitted parenterally, can cause chronic disease and hepatocellular carcinoma. The latter will be implied in a question via mention of alpha-fetoprotein (the tumor marker for HCC; it’s also the tumor-marker for yolk-sac [endodermal sinus] and mixed germ cell tumors).

RNA viruses If they tell you a patient has HepC (or HepB or EtOHism), and then they show you a liver with lots of neoplastic lesions  colonic metastases, NOT primary HCC. So HY. USMLE wants you to realize that a primary HCC is typically a solitary lesion.

RNA viruses If they tell you a patient has HepC (or HepB or EtOHism), and then they show you a liver with lots of neoplastic lesions  colonic metastases, NOT primary HCC. So HY. USMLE wants you to realize that a primary HCC is typically a solitary lesion. Sometimes instead of listing “colonic adenocarcinoma” or “HCC” as answer choices, they’ll just ask for the tumor marker. In the above case, it would be CEA, not alpha-FP. Alpha-FP is HCC; colon cancer is CEA.

RNA viruses For west nile virus, just remember that the pt is yellow (jaundice) and that he or she has mid-zone necrosis of the liver (zone-2).

RNA viruses For west nile virus, just remember that the pt is yellow (jaundice) and that he or she has mid-zone necrosis of the liver (zone-2). For dengue fever, remember that the pt will have thrombocytopenia, severe back pain, and severe retro-ocular headache.

RNA viruses For west nile virus, just remember that the pt is yellow (jaundice) and that he or she has mid-zone necrosis of the liver (zone-2). For dengue fever, remember that the pt will have thrombocytopenia, severe back pain, and severe retro-ocular headache. I’ve never seen Sx of Japanese encephalitis asked in a question before.

RNA viruses But here’s where your points are. So if you’ve made it this far in the presentation, here’s your reward:

RNA viruses But here’s where your points are. So if you’ve made it this far in the presentation, here’s your reward: For the sake of the USMLE, they want you to know that Japanese encephalitis and Dengue fever are transmitted by the Aedes mosquito, but West Nile virus is transmitted by the CULEX mosquito.

RNA viruses But here’s where your points are. So if you’ve made it this far in the presentation, here’s your reward: For the sake of the USMLE, they want you to know that Japanese encephalitis and Dengue fever are transmitted by the Aedes mosquito, but West Nile virus is transmitted by the CULEX mosquito. Seemingly ridiculous, but know it. West Nile virus is transmitted by the Culex mosquito, and its reservoir is birds.

RNA viruses The SS(+)-diploid icosahedral, enveloped RNA viruses are HIV1/2 and HTLV1/2 (discuss)

RNA viruses The SS(+)-diploid icosahedral, enveloped RNA viruses are HIV1/2 and HTLV1/2 (discuss) HTLV  mycosis fungoides / Sezary syndrome

RNA viruses The SS(+)-diploid icosahedral, enveloped RNA viruses are HIV1/2 and HTLV1/2 (discuss) HTLV  mycosis fungoides / Sezary syndrome HTLV also causes TROPICAL SPASTIC PARAPARESIS. I’ve seen this rock up in a question. Abs against infected T-cells attack neural cells and cause muscle weakness/stiffness in the legs.

RNA viruses The SS(+)-diploid icosahedral, enveloped RNA viruses are HIV1/2 and HTLV1/2 (discuss) HTLV  mycosis fungoides / Sezary syndrome HTLV also causes TROPICAL SPASTIC PARAPARESIS. I’ve seen this rock up in a question. Abs against infected T-cells attack neural cells and cause muscle weakness/stiffness in the legs. In Sezary’s, you’ve got Pautrier microabscesses (T-cell collections). Don’t confuse with the Munro microabscesses of psoriasis (neutrophils in the skin).

RNA viruses The helical RNA viruses are divided into SS(+) non-segmented, SS(-) segmented and SS(-) non-segmented.

RNA viruses The helical RNA viruses are divided into SS(+) non-segmented, SS(-) segmented and SS(-) non-segmented. The SS(+) non-segmented one is coronaviridae  coronavirus  causes SARS

RNA viruses The helical RNA viruses are divided into SS(+) non-segmented, SS(-) segmented and SS(-) non-segmented. The SS(+) non-segmented one is coronaviridae  coronavirus  causes SARS The SS(-) segmented ones are orthomyxoviridae and bunyaviridae.

RNA viruses The helical RNA viruses are divided into SS(+) non-segmented, SS(-) segmented and SS(-) non-segmented. The SS(+) non-segmented one is coronaviridae  coronavirus  causes SARS The SS(-) segmented ones are orthomyxoviridae and bunyaviridae. Orthomyxoviridae are the influenza A, B + C viruses

RNA viruses Bunyaviridae  bunyavirus + hantavirus (mice + haemorrhagic pulmonary syndrome).

RNA viruses Bunyaviridae  bunyavirus + hantavirus (mice + haemorrhagic pulmonary syndrome). The USMLE, for whatever reason, wants you to know that hantavirus is transmitted by mice. There are quite a few “low-yield” viruses, but consider this detail one of the highest-yield of the low-yield. I’ve seen it in a few questions. Hantavirus is transmitted by mice. I even have a friend on SDN who had hantavirus show up on his/her real deal.

RNA viruses For influenza, you need to remember that it’s HIGHLY SEGMENTED, and that reassortment of the segments with animal viruses leads to antigenic Shift.

RNA viruses For influenza, you need to remember that it’s HIGHLY SEGMENTED, and that reassortment of the segments with animal viruses leads to antigenic Shift. In contrast, point mutations in haemagglutinin and neuraminidase lead to antigenic Drift.

RNA viruses For influenza, you need to remember that it’s HIGHLY SEGMENTED, and that reassortment of the segments with animal viruses leads to antigenic Shift. In contrast, point mutations in haemagglutinin and neuraminidase lead to antigenic Drift. You’ll know it’s a shift vs drift bc shift causes PANdemic (worldwide or continental-magnitude disease), whereas drift causes EPIdemic (towns or states).

RNA viruses If they ask about the target of an influenza vaccine, the answer is ALWAYS HAEMAGGLUTININ. Remember that. I talk about this more specifically at the end of this lecture, but haemagglutinin mediates viral attachment. Vaccines target this molecule. Neuraminidase inhibitors (-mivirs), in contrast, prevent viral spread (“cells packed with virions”).

RNA viruses If they ask about the target of an influenza vaccine, the answer is ALWAYS HAEMAGGLUTININ. Remember that. I talk about this more specifically at the end of this lecture, but haemagglutinin mediates viral attachment. Vaccines target this molecule. Neuraminidase inhibitors (-mivirs), in contrast, prevent viral spread (“cells packed with virions”). They also, once again, want you to remember that rotavirus, like influenza virus, is highly segmented.

RNA viruses The helical, enveloped SS(-) non-segmented ones are paramyxoviridae, rhabdoviridae, filoviridae and arenaviridae.

RNA viruses The helical, enveloped SS(-) non-segmented ones are paramyxoviridae, rhabdoviridae, filoviridae and arenaviridae. Paramyxoviridae  parainfluenza virus (paramyxovirus), pneumovirus (RSV), rubulavirus and morbillivirus

RNA viruses For parainfluenza virus, remember that it causes laryngotracheobronchitis (croup), which has a seal-like barking cough. This causes a steeple-sign on lateral x-ray (in contrast, epiglottitis causes a thumb-print sign on x-ray; know that for DDx).

RNA viruses For parainfluenza virus, remember that it causes laryngotracheobronchitis (croup), which has a seal-like barking cough. This causes a steeple-sign on lateral x-ray (in contrast, epiglottitis causes a thumb-print sign on x-ray; know that for DDx). For pneumovirus, it’s aka respiratory syncytial virus (RSV). It’s the most common cause of bronchiolitis in infants. If there’s any “pneumonia”-type presentation in an infant  RSV; Tx w/ ribavirin.

RNA viruses For clarification purposes: Rubulavirus = mumps
Morbillivirus = measles = ruBeola Those two are paramyxoviridae. Don’t confuse with: Rubivirus = rubella = German measles = three-day measles; this is Togaviridae In addition, roSeola infantum = HHV-6. Don’t confuse with ruBeola, which is measles.  This slide is very important.

RNA viruses For mumps, just remember MOP: meningitis, orchitis, parotitis.

RNA viruses For mumps, just remember MOP: meningitis, orchitis, parotitis. For measles, just remember that the rash starts at the head and moves to the toes.

RNA viruses For mumps, just remember MOP: meningitis, orchitis, parotitis. For measles, just remember that the rash starts at the head and moves to the toes. You also need to be extremely aware of subacute sclerosing pan-encephalitis (SSPE) as a disease associated with measles.

RNA viruses For SSPE, you’ve gotta know that sometimes children can get measles, the infection resolves, but that the virus can remain latent in the CNS, only to re-present later as SSPE. This occurs in M-protein-negative measles strains, and there will concomitantly be no evidence of anti-M-protein Abs in the CNS.

RNA viruses They’ll tell you a 10-yr-old girl was perfectly normal, but then started doing poorly in school, got myalgias and then rapidly deteriorated and died. They’ll ask for which organism is responsible. It’s measles. You’ve gotta know this is SSPE. Holy cow. I’d say this is a 240+ question, but it’s ludicrously HY and is very commonly asked.

RNA viruses They’ll tell you a 10-yr-old girl was perfectly normal, but then started doing poorly in school, got myalgias and then rapidly deteriorated and died. They’ll ask for which organism is responsible. It’s measles. You’ve gotta know this is SSPE. Holy cow. I’d say this is a 240+ question, but it’s ludicrously HY and is very commonly asked. Or they might tell you a 17-yr-old immigrant had similar Sx  you’d need to infer that her immigrant status means she likely wasn’t immunized with MMR when younger, and she got SSPE subsequently. HY!!

RNA viruses Another thing: all paramyxoviridae produce F-protein, which allows them to spread cell-to-cell via syncytia formation.

RNA viruses Another thing: all paramyxoviridae produce F-protein, which allows them to spread cell-to-cell via syncytia formation. Palivizumab targets F-protein.

RNA viruses Another thing: all paramyxoviridae produce F-protein, which allows them to spread cell-to-cell via syncytia formation. Palivizumab targets F-protein. You’ve gotta realize that syncytia formation means the virus has very little exposure to the humoral environment. This means very strong CD8+ immunity is needed to kill it. If they ask you for which virus requires really good intracellular immunity, you know it’s any one of the four paramyxoviridae.

RNA viruses Filoviridae  filovirus  subdivided into Marburg + ebola viruses

RNA viruses Filoviridae  filovirus  subdivided into Marburg + ebola viruses Arenaviridae  lymphocytic choriomeningitis virus aka lassavirus

RNA viruses Filoviridae  filovirus  subdivided into Marburg + ebola viruses Arenaviridae  lymphocytic choriomeningitis virus aka lassavirus Rhabdoviridae  lyssavirus (rabies)

RNA viruses For lyssavirus (rabies), it’s actually very HY to know that it looks bullet-shaped on EM. I’ve seen this in a couple questions.

RNA viruses For lyssavirus (rabies), it’s actually very HY to know that it looks bullet-shaped on EM. I’ve seen this in a couple questions. It also has a very long incubation period (up to several months).

RNA viruses For lyssavirus (rabies), it’s actually very HY to know that it looks bullet-shaped on EM. I’ve seen this in a couple questions. It also has a very long incubation period (up to several months). Skunks, bats, wild dogs and raccoons are reservoirs.

RNA viruses For lyssavirus (rabies), it’s actually very HY to know that it looks bullet-shaped on EM. I’ve seen this in a couple questions. It also has a very long incubation period (up to several months). Skunks, bats, wild dogs and raccoons are reservoirs. It ascends MOTOR neurons to the CNS.

RNA viruses For lyssavirus (rabies), it’s actually very HY to know that it looks bullet-shaped on EM. I’ve seen this in a couple questions. It also has a very long incubation period (up to several months). Skunks, bats, wild dogs and raccoons are reservoirs. It ascends MOTOR neurons to the CNS. If bit by animal, first step is IV immunoglobulin, THEN killed virus vaccine. Ok? IV immunoglobulin first (passive immunity), THEN give the killed vaccine (active immunity).

RNA viruses The only organism that has a longer incubation period than rabies is elephantitis (~9 months; lymphadenopathy), which is Wuchereria bancrofti, transmitted by female mosquito.

RNA viruses For ebola/marburg, just know that primates can transmit the virus and it’s rapidly fatal. I may have only seen one question on ebola, and it was pretty obvious. Realize that the rarer the condition, the more obvious they’ll make the vignette.

RNA viruses For ebola/marburg, just know that primates can transmit the virus and it’s rapidly fatal. I may have only seen one question on ebola, and it was pretty obvious. Realize that the rarer the condition, the more obvious they’ll make the vignette. I’ve never seen a question on lymphocytic choriomeningitis virus (arenavirus) beyond just knowing its structure and that it’s rodent-transmitted.

RNA viruses All RNA viruses replicate in the cytoplasm EXCEPT FOR THE LENTIVIRIDAE (retroviruses) AND INFLUENZA, WHICH REQUIRE THE NUCLEUS.

RNA viruses All RNA viruses replicate in the cytoplasm EXCEPT FOR THE LENTIVIRIDAE (retroviruses) AND INFLUENZA, WHICH REQUIRE THE NUCLEUS. SS(+) non-segmented RNA viruses are notable for synthesizing their proteins as a SINGLE TRANSLATIONAL TRANSCRIPT THAT IS SUBSEQUENTLY CLEAVED (retarded detail, but I’ve seen it in a question).

DNA viruses (hooray)

DNA viruses Icosahedral or complex nucleocapsids.

DNA viruses Icosahedral or complex nucleocapsids.
The only virus with a complex nucleocapsid is Poxvirus. It’s DS-linear and is the only DNA virus that DOESN’T NEED THE NUCLEUS TO REPLICATE.

DNA viruses For the icosahedral ones, there are non-enveloped and enveloped types.

DNA viruses For the icosahedral ones, there are non-enveloped and enveloped types. The non-enveloped are SS-linear, DS-circular and DS-linear.

DNA viruses The SS-linear icosahedral non-enveloped DNA virus is erythrovirus (aka parvovirus B19).  slapped cheek appearance; once rash forms VIRUS HAS BEEN CLEARED AND PARENTS CAN BE TOLD CHILD DOESN’T NEED Tx. Aplastic anaemia in children and ARTHRITIS IN ADULTS (oh em gee high-yield wowwies); PB19 crosses placenta (add to TORCHeS)

DNA viruses How would the USMLE throw the PB19 aplastic anaemia at you? ..”giant red cell precursors seen on BM biopsy”  indicative of pure red-cell aplasia. Just take it as a lesson that on the real deal, they’ll take pretty much any and every concept and indirectly relate to it, rather than just telling you straight-up.

DNA viruses I’ve also seen in a question that PB19 binds to P-antigen, aka globoside, on the RBC surface. Don’t confuse that P with that in Palivizumab for F-protein (syncytia formation in paramyxoviridae  they’ll ask you which virus needs super-high CD8 for immunity  bc syncytium means virus doesn’t see humoral environment!).

DNA viruses The DS-circular non-enveloped icosahedral DNA viruses are the papovaviridae.

DNA viruses The DS-circular non-enveloped icosahedral DNA viruses are the papovaviridae. These are HPV and JC/BK polyomaviruses.  When PML (JC) appears, the USMLE wants you to know that it’s always because of REACTIVATION OF LATENT VIRUS (holy cow), NOT because of recent infection in immunocompromised. PML shows up in immunocompromised so the latter is juicy, but the former is right. BK affects the kidneys (BK = kidney)  all you need to know about BK.

DNA viruses For HPV, just know that is causes koilocytes (large, irregular cells with peri-nuclear halos on Pap-smear) and cervical cancer. Be familiar with cervical cancer histology; that’s really HY.

DNA viruses For HPV, just know that is causes koilocytes (large, irregular cells with peri-nuclear halos on Pap-smear) and cervical cancer. Be familiar with cervical cancer histology; that’s really HY. HPV-6/11 cause condyloma acuminata (warts); HPV-16/18/31/33/45 cause cervical cancer.

DNA viruses The other thing is that the papovaviridae are SUPERCOILED circular, whereas HepB (to be discussed soon) is PARTIAL circular.

DNA viruses The other thing is that the papovaviridae are SUPERCOILED circular, whereas HepB (to be discussed soon) is PARTIAL circular. As far as I can remember, when PML shows up in a question, they’ll mention it as MANY NON-CONTRASTING LESIONS on MRI. I’ve seen that in a few questions.

DNA viruses The icosahedral non-enveloped DS-linear DNA virus is adenovirus.  just remember CONJUNCTIVITIS and HAEMORRHAGIC CYSTITIS. Conjunctivitis will be straightforward. For HC, they’ll mention a bunch of kids at daycare with reddish urine and then ask you for the virus; they’ll throw rotavirus in there for kicks just bc that’s so common in infants, but it’s adenovirus. NOT ROTA

DNA viruses The enveloped icosahedral DNA viruses are the herpesviridae and hepadnaviridae (HepB).

DNA viruses For herpes, they like “intranuclear inclusions” for Cowdry bodies. “Punched out” ulcers is herpes. “Linear ulcers” is CMV.

DNA viruses For herpes, they like “intranuclear inclusions” for Cowdry bodies. “Punched out” ulcers is herpes. “Linear ulcers” is CMV. HepB is enveloped, icosahedral and circular, not linear.

DNA viruses For herpes, they like “intranuclear inclusions” for Cowdry bodies. “Punched out” ulcers is herpes. “Linear ulcers” is CMV. HepB is enveloped, icosahedral and circular, not linear. HepB’s DNA-dependent DNA-polymerase is mega-high-yield to remember. If they ask you about HepB’s enzyme, the DNA-d-DNA-pol is >>> important than its reverse transcriptase, but remember both.

DNA viruses For herpes, they like “intranuclear inclusions” for Cowdry bodies. “Punched out” ulcers is herpes. “Linear ulcers” is CMV. HepB is enveloped, icosahedral and circular, not linear. HepB’s DNA-dependent DNA-polymerase is mega-high-yield to remember. If they ask you about HepB’s enzyme, the DNA-d-DNA-pol is >>> important than its reverse transcriptase, but remember both. HepD (deltavirus) requires HepB to form envelope; prevention for HepD is HepB vaccination.

DNA viruses Remember that for Herpes, they cause Cowdry A bodies. These are intra-NUCLEAR inclusions. I also just want to point out that WARTHIN-FINKELDEY cells, caused by MEASLES, are VERY SIMILAR histologically to cells w/ herpes-induced Cowdry A bodies. So be aware of the patient’s overall presentation/Hx to make the correct diagnosis.

DNA viruses HHV1/2 = HSV1/2; HSV1 = herpes labialis (oral), whereas HSV2 = genital; they can be seen swapped, but for the purpose of the USMLE, those are the associations.

DNA viruses HHV1/2 = HSV1/2; HSV1 = herpes labialis (oral), whereas HSV2 = genital; they can be seen swapped, but for the purpose of the USMLE, those are the associations. HHV-3 = chickenpox (“crops of vesicles on the trunk”) = varicella zoster; can present years later as shingles (herpes zoster; not a different virus, but herpes zoster is literally the other name for shingles); if shingles  pain (herpetic neuralgia) and vesicles in a dermatomal distribution. Antivirals discussed later in this lecture.

DNA viruses HHV4 = EBV  mononucleosis (“atypical lymphocytes” on blood smear  they’re CD8+ T-CELLS NOT B-CELLS, DESPITE the virus normally infecting B-cells)  splenomegaly (pt with mono should avoid contact sports bc spleen is most easily ruptured abdominal organ, particularly when enlarged). Can cause Burkitt’s lymphoma.

DNA viruses HHV5 = CMV  commonly spread via renal transplantation or blood transfusions; causes blueberry muffin rash + hepatomegaly in neonate if TORCHeS. CMV colitis occurs in HIV pts w/ <50 CD4+ count; remember “linear ulcers.” Retinitis is most common CMV manifestation (CD4+ <200). Antivirals discussed later in this lecture.

DNA viruses HHV5 = CMV  commonly spread via renal transplantation or blood transfusions; causes blueberry muffin rash + hepatomegaly in neonate if TORCHeS. CMV colitis occurs in HIV pts w/ <50 CD4+ count; remember “linear ulcers.” Retinitis is most common CMV manifestation (CD4+ <200). Antivirals discussed later in this lecture. Remains latent in mononuclear cells (in contrast to EBV, which remains latent in B-cells)

DNA viruses HHV6 = roseola infantum = spiking fever followed by rash. That’s all you need to know about it.

DNA viruses HHV6 = roseola infantum = spiking fever followed by rash. That’s all you need to know about it. HHV8 causes Kaposi’s sarcoma in HIV pts (abnormal endothelial/vascular proliferations histologically), body-fluid lymphoma, and Castleman’s disease (non-cancerous lymph node growths). Kaposi’s can occur in the GIT  blood in stool. Bacillary angiomatosis (caused by bartonella henselae) can cause Kaposi-like lesions, except there will be neutrophils on biopsy instead of the vascular proliferations  don’t **** that up.

DNA viruses You’ve gotta know that all viruses derive their envelopes from the cell membrane, but herpesviridae GET IT FROM THE NUCLEAR MEMBRANE.

DNA viruses You’ve gotta know that all viruses derive their envelopes from the cell membrane, but herpesviridae GET IT FROM THE NUCLEAR MEMBRANE. You’ve also gotta know that dsDNA and SS(+)RNA viruses are infective VIA PURIFIED NUCLEIC ACID ALONE  they’ll ask you this to see if you understand the molecular biology

Antivirals Amantadine  blocks viral uncoating; mutated M2 protein = resistance; can cause ATAXIA; can be used for Parkinson’s disease, rubella and influenza; RImantidine has fewer CNS side-effects bc it doesn’t cross the BBB. You’ve also gotta know that antivirals reduce the length of Sx by days.  I’ve seen this in a question where “reduce Sx duration by half” was also an answer choice.

Antivirals For oseltamivir / zanamivir, they’ll tell you that a med was given and now the cells are “filled with virions.”  prevent viral release; they’ll also ask you for which drug prevents the spread of virus the best, and the –mivirs are right. They’re SIALIC ACID ANALOGUES. You’ve gotta know haemagglutinin and neurominidase, where sialic acid is cleaved by the latter for release. If they ask about the target of the best vaccine, the answer is ALWAYS HAEMAGGLUTININ (exceedingly high-yield).

Antivirals Ribavirin is used for HepC and RSV.  high-yield. I’ve also seen in a question that ribavirin CAUSES HAEMOLYTIC ANAEMIA. That’s in FA too btw. Ribavirin inhibits IMP dehydrogenase. UWorld went into extensive detail about ribavirin mechanisms, but the extent that is important is that there is decreased IMP to GMP conversion.

Antivirals Acyclovir  HHV1-4; guanosine analogue. Just know that HHV1-4 phosphorylate the drug to the monophosphate. Cellular kinases then bring the G*MP to the G*TP form. HHV1-4 resistance is due to LACK (NOT ALTERED) OF VIRAL THYMIDINE KINASE. I’ve seen altered kinase and lack of kinase as answers to the same question; the latter is the real deal and also in FA. Acylcovir (not oral) decreases LENGTH of outbreak; daily oral VALacyclovir decreases RECURRENCE of outbreaks. USMLE wants you to know that the drug causes CHAIN TERMINATION. FAMcyclovir is for shingles (HY).

Antivirals Ganciclovir is for CMV (HHV5).
Ultra high-yield: CMV has increased susceptibility to this drug bc of DIFFERENT DNA POLYMERASE STRUCTURE. Mechanism of phosphorylation similar to w/ acyclovir. Side-effects for this drug are EXCEEDINGLY HIGH-Y. NEUTROPENIA (and leuko-/thrombocytopenia) is the big one. They’ll give you a vignette of someone with a drop in grans who’s taking an anti-viral (won’t be obvious at all, so remember the neutropenia). They could even be tricky and ask for what was being treated (so you’d have to know the drop in grans was bc of ganciclovir, that CMV must have been the organism treated, and that the pt may have had retinitis/colitis).

Antivirals Foscarnet  just know this is for ganciclovir-refractory CMV. Like ganciclovir, its side-effects are ultra-HY: NEPHROTOXICITY and HYPOCALCAEMIA, -KALAEMIA, -MAGNAESEMIA. Crazy HY. It’s a pyrophosphate analogue, so it doesn’t require the initial phosphorylation that ganciclovir does. They’ll ask you this. Cidofovir is in FA, but I’ve actually never seen it rock up in a question. Just know that it also is nephrotoxic and doesn’t need the initial phosphorylation, so it’s used for acyclovir-refractory illness.

USMLE – viruses Phloston.

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USMLE – viruses Phloston.

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