USMLE viruses

USMLE virusesPhlostonAll info in this presentation is high-yield. I had two questions on my real deal that involved viral structural identification.RNA virusesRNA virusesIcosahedral or helical nucleocapsidsRNA virusesIcosahedral or helical nucleocapsidsIcosahedral are either enveloped or non-enveloped. Helicals are always enveloped.RNA virusesIcosahedral or helical nucleocapsidsIcosahedral are either enveloped or non-enveloped. Helicals are always enveloped.For icosahedral, non-enveloped viruses, youve got SS(+) non-segmented and DS-segmented.RNA virusesIcosahedral or helical nucleocapsidsIcosahedral are either enveloped or non-enveloped. Helicals are always enveloped.For icosahedral, non-enveloped viruses, youve got SS(+) non-segmented and DS-segmented.SS(+) non-segmented, non-enveloped icosahedral viruses are split into picornaviridae and caliciviridae.RNA virusesIcosahedral or helical nucleocapsidsIcosahedral are either enveloped or non-enveloped. Helicals are always enveloped.For icosahedral, non-enveloped viruses, youve 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 virusesThe enteroviruses comprise polio, HepA, coxsackie and echovirus.RNA virusesThe 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 virusesThe 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 vaccineRNA virusescoxsackieA herpangina (if instead herpes theyll imply Cowdry bodies via mention of intranuclear inclusions), hand-foot-mouth diseaseRNA virusescoxsackieA herpangina (if instead herpes theyll imply Cowdry bodies via mention of intranuclear inclusions), hand-foot-mouth diseasecoxsackie-B most common cause of viral myocarditis; DIRECT-VIRAL DAMAGE (NOT type-II HS, like rheumatic heart disease); DCMRNA virusescoxsackieA herpangina (if instead herpes theyll imply Cowdry bodies via mention of intranuclear inclusions), hand-foot-mouth diseasecoxsackie-B most common cause of viral myocarditis; DIRECT-VIRAL DAMAGE (NOT type-II HS, like rheumatic heart disease); DCMechovirus meningitis; theyll tell you kids got meningitis from RNA virus and then ask you for the structure (i.e. non-enveloped, ssRNA virus)RNA virusesRhinovirus most common cause of the common cold (high-% question); contraction occurs via ICAM-1 (CD54) know that. Sometimes theyll ask you for the picornavirus thats respiratory-contracted.RNA virusesRhinovirus most common cause of the common cold (high-% question); contraction occurs via ICAM-1 (CD54) know that. Sometimes theyll ask you for the picornavirus thats 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, its correct over caliciviridae, but remember both (just do it; Ive seen both in practice questions).RNA virusesUSMLE likes Norwalk virus for cruise ships (anything where a lot of people in close contact come down with a gastroenteritis).RNA virusesUSMLE likes Norwalk virus for cruise ships (anything where a lot of people in close contact come down with a gastroenteritis).For HepE, youve just gotta remember pregnant women (highest yield), Asia > USA (particularly Tibet), and of course its enteric.RNA virusesAs 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 virusesAs 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 virusesRotavirus 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. Theyll ask you for the virus that can undergo genetic modulation similar to influenza.RNA virusesColtivirus (reovirus) causes Colorado Tick fever. Ive never encountered a question on this. But I would be aware of the viral structure regardless.RNA virusesThe 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 virusesThe 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 flaviviridaeRNA virusesThe 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 flaviviridaeTogaviridae are alpha virus (equine encephalitides) and rubivirus (rubella)RNA virusesThe 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 flaviviridaeTogaviridae are alpha virus (equine encephalitides) and rubivirus (rubella)Flaviviridae are HepC, West Nile, Yellow/Dengue fevers, Japanese encephalitisRNA virusesFor the equine encephalitides, theres EEE, WEE and VEE for Eastern, Western and Venezuelan equine encephalitis, respectively.RNA virusesFor the equine encephalitides, theres 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 virusesFor the equine encephalitides, theres 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 virusesFor HepC, be aware that it has the longest incubation period (in contrast to HepA, which has the shortest).RNA virusesFor 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. Ive 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 virusesYou 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 its pegylated, its HepC, not B; if its regular, its HepB Tx.RNA virusesYou 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 its pegylated, its HepC, not B; if its regular, its HepB Tx.HepC is transmitted via blood. That means, it is NOT TRANSMISSIBLE BY SEX. Obviously if theres menstruation, theres a risk, but for the purpose of the USMLE, HepB is transmissible by sex, but HepC is not.RNA virusesLike 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; its also the tumor-marker for yolk-sac [endodermal sinus] and mixed germ cell tumors).RNA virusesIf 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 virusesIf 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, theyll 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 virusesFor 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 virusesFor 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 virusesFor 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.Ive never seen Sx of Japanese encephalitis asked in a question before.RNA virusesBut heres where your points are. So if youve made it this far in the presentation, heres your reward:RNA virusesBut heres where your points are. So if youve made it this far in the presentation, heres 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 virusesBut heres where your points are. So if youve made it this far in the presentation, heres 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 virusesThe SS(+)-diploid icosahedral, enveloped RNA viruses are HIV1/2 and HTLV1/2 (discuss)RNA virusesThe SS(+)-diploid icosahedral, enveloped RNA viruses are HIV1/2 and HTLV1/2 (discuss)HTLV mycosis fungoides / Sezary syndromeRNA virusesThe SS(+)-diploid icosahedral, enveloped RNA viruses are HIV1/2 and HTLV1/2 (discuss)HTLV mycosis fungoides / Sezary syndromeHTLV also causes TROPICAL SPASTIC PARAPARESIS. Ive seen this rock up in a question. Abs against infected T-cells attack neural cells and cause muscle weakness/stiffness in the legs. RNA virusesThe SS(+)-diploid icosahedral, enveloped RNA viruses are HIV1/2 and HTLV1/2 (discuss)HTLV mycosis fungoides / Sezary syndromeHTLV also causes TROPICAL SPASTIC PARAPARESIS. Ive seen this rock up in a question. Abs against infected T-cells attack neural cells and cause muscle weakness/stiffness in the legs. In Sezarys, youve got Pautrier microabscesses (T-cell collections). Dont confuse with the Munro microabscesses of psoriasis (neutrophils in the skin).RNA virusesThe helical RNA viruses are divided into SS(+) non-segmented, SS(-) segmented and SS(-) non-segmented.RNA virusesThe helical RNA viruses are divided into SS(+) non-segmented, SS(-) segmented and SS(-) non-segmented.The SS(+) non-segmented one is coronaviridae coronavirus causes SARSRNA virusesThe helical RNA viruses are divided into SS(+) non-segmented, SS(-) segmented and SS(-) non-segmented.The SS(+) non-segmented one is coronaviridae coronavirus causes SARSThe SS(-) segmented ones are orthomyxoviridae and bunyaviridae.RNA virusesThe helical RNA viruses are divided into SS(+) non-segmented, SS(-) segmented and SS(-) non-segmented.The SS(+) non-segmented one is coronaviridae coronavirus causes SARSThe SS(-) segmented ones are orthomyxoviridae and bunyaviridae.Orthomyxoviridae are the influenza A, B + C virusesRNA virusesBunyaviridae bunyavirus + hantavirus (mice + haemorrhagic pulmonary syndrome).

RNA virusesBunyaviridae 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. Ive 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 virusesFor influenza, you need to remember that its HIGHLY SEGMENTED, and that reassortment of the segments with animal viruses leads to antigenic Shift.RNA virusesFor influenza, you need to remember that its 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 virusesFor influenza, you need to remember that its 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.Youll know its a shift vs drift bc shift causes PANdemic (worldwide or continental-magnitude disease), whereas drift causes EPIdemic (towns or states).RNA virusesIf 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 virusesIf 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 virusesThe helical, enveloped SS(-) non-segmented ones are paramyxoviridae, rhabdoviridae, filoviridae and arenaviridae.RNA virusesThe helical, enveloped SS(-) non-segmented ones are paramyxoviridae, rhabdoviridae, filoviridae and arenaviridae.Paramyxoviridae parainfluenza virus (paramyxovirus), pneumovirus (RSV), rubulavirus and morbillivirusRNA virusesFor 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 virusesFor 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, its aka respiratory syncytial virus (RSV). Its the most common cause of bronchiolitis in infants. If theres any pneumonia-type presentation in an infant RSV; Tx w/ ribavirin.RNA virusesFor clarification purposes:Rubulavirus = mumpsMorbillivirus = measles = ruBeolaThose two are paramyxoviridae.Dont confuse with:Rubivirus = rubella = German measles = three-day measles; this is TogaviridaeIn addition, roSeola infantum = HHV-6. Dont confuse with ruBeola, which is measles. This slide is very important.RNA virusesFor mumps, just remember MOP: meningitis, orchitis, parotitis.RNA virusesFor mumps, just remember MOP: meningitis, orchitis, parotitis.For measles, just remember that the rash starts at the head and moves to the toes.RNA virusesFor 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 virusesFor SSPE, youve 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 virusesTheyll 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. Theyll ask for which organism is responsible. Its measles. Youve gotta know this is SSPE. Holy cow. Id say this is a 240+ question, but its ludicrously HY and is very commonly asked.RNA virusesTheyll 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. Theyll ask for which organism is responsible. Its measles. Youve gotta know this is SSPE. Holy cow. Id say this is a 240+ question, but its ludicrously HY and is very commonly asked.Or they might tell you a 17-yr-old immigrant had similar Sx youd need to infer that her immigrant status means she likely wasnt immunized with MMR when younger, and she got SSPE subsequently. HY!!RNA virusesAnother thing: all paramyxoviridae produce F-protein, which allows them to spread cell-to-cell via syncytia formation.RNA virusesAnother thing: all paramyxoviridae produce F-protein, which allows them to spread cell-to-cell via syncytia formation.Palivizumab targets F-protein.RNA virusesAnother thing: all paramyxoviridae produce F-protein, which allows them to spread cell-to-cell via syncytia formation.Palivizumab targets F-protein.Youve 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 its any one of the four paramyxoviridae.RNA virusesFiloviridae filovirus subdivided into Marburg + ebola viruses

RNA virusesFiloviridae filovirus subdivided into Marburg + ebola virusesArenaviridae lymphocytic choriomeningitis virus aka lassavirusRNA virusesFiloviridae filovirus subdivided into Marburg + ebola virusesArenaviridae lymphocytic choriomeningitis virus aka lassavirusRhabdoviridae lyssavirus (rabies)RNA virusesFor lyssavirus (rabies), its actually very HY to know that it looks bullet-shaped on EM. Ive seen this in a couple questions.RNA virusesFor lyssavirus (rabies), its actually very HY to know that it looks bullet-shaped on EM. Ive seen this in a couple questions.It also has a very long incubation period (up to several months).RNA virusesFor lyssavirus (rabies), its actually very HY to know that it looks bullet-shaped on EM. Ive 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 virusesFor lyssavirus (rabies), its actually very HY to know that it looks bullet-shaped on EM. Ive 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 virusesFor lyssavirus (rabies), its actually very HY to know that it looks bullet-shaped on EM. Ive 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 virusesThe only organism that has a longer incubation period than rabies is elephantitis (~9 months; lymphadenopathy), which is Wuchereria bancrofti, transmitted by female mosquito.RNA virusesFor ebola/marburg, just know that primates can transmit the virus and its 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 theyll make the vignette.RNA virusesFor ebola/marburg, just know that primates can transmit the virus and its 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 theyll make the vignette.Ive never seen a question on lymphocytic choriomeningitis virus (arenavirus) beyond just knowing its structure and that its rodent-transmitted.RNA virusesAll RNA viruses replicate in the cytoplasm EXCEPT FOR THE LENTIVIRIDAE (retroviruses) AND INFLUENZA, WHICH REQUIRE THE NUCLEUS.RNA virusesAll 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 Ive seen it in a question).DNA viruses (hooray)DNA virusesIcosahedral or complex nucleocapsids.DNA virusesIcosahedral or complex nucleocapsids.The only virus with a complex nucleocapsid is Poxvirus. Its DS-linear and is the only DNA virus that DOESNT NEED THE NUCLEUS TO REPLICATE.

DNA virusesFor the icosahedral ones, there are non-enveloped and enveloped types.DNA virusesFor the icosahedral ones, there are non-enveloped and enveloped types.The non-enveloped are SS-linear, DS-circular and DS-linear.DNA virusesThe 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 DOESNT NEED Tx. Aplastic anaemia in children and ARTHRITIS IN ADULTS (oh em gee high-yield wowwies); PB19 crosses placenta (add to TORCHeS)DNA virusesHow 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, theyll take pretty much any and every concept and indirectly relate to it, rather than just telling you straight-up.DNA virusesIve also seen in a question that PB19 binds to P-antigen, aka globoside, on the RBC surface. Dont confuse that P with that in Palivizumab for F-protein (syncytia formation in paramyxoviridae theyll ask you which virus needs super-high CD8 for immunity bc syncytium means virus doesnt see humoral environment!).DNA virusesThe DS-circular non-enveloped icosahedral DNA viruses are the papovaviridae.DNA virusesThe 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 its 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 virusesFor 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; thats really HY.DNA virusesFor 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; thats really HY.HPV-6/11 cause condyloma acuminata (warts); HPV-16/18/31/33/45 cause cervical cancer.DNA virusesThe other thing is that the papovaviridae are SUPERCOILED circular, whereas HepB (to be discussed soon) is PARTIAL circular.DNA virusesThe 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, theyll mention it as MANY NON-CONTRASTING LESIONS on MRI. Ive seen that in a few questions.DNA virusesThe icosahedral non-enveloped DS-linear DNA virus is adenovirus. just remember CONJUNCTIVITIS and HAEMORRHAGIC CYSTITIS. Conjunctivitis will be straightforward. For HC, theyll mention a bunch of kids at daycare with reddish urine and then ask you for the virus; theyll throw rotavirus in there for kicks just bc thats so common in infants, but its adenovirus.DNA virusesThe enveloped icosahedral DNA viruses are the herpesviridae and hepadnaviridae (HepB).DNA virusesFor herpes, they like intranuclear inclusions for Cowdry bodies. Punched out ulcers is herpes. Linear ulcers is CMV.DNA virusesFor 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 virusesFor 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.HepBs DNA-dependent DNA-polymerase is mega-high-yield to remember. If they ask you about HepBs enzyme, the DNA-d-DNA-pol is >>> important than its reverse transcriptase, but remember both.DNA virusesFor 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.HepBs DNA-dependent DNA-polymerase is mega-high-yield to remember. If they ask you about HepBs 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 virusesRemember 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 patients overall presentation/Hx to make the correct diagnosis.DNA virusesHHV1/2 = 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 virusesHHV1/2 = 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 virusesHHV4 = EBV mononucleosis (atypical lymphocytes on blood smear theyre 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 Burkitts lymphoma.DNA virusesHHV5 = 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/