Herpesviruses

00:01 Herpesiridae viruses.

00:05 The herpesviruses constitute a large number of viruses, and we'll go through them by name and number just very shortly, but all of them contain a large enveloped, nuclear membrane.

00:17 They all have an icosadeltahedral capsid.

00:21 But important to remember in terms of both clinical use and testing is that the herpesviruses have a double- stranded DNA genome which is linear.

00:31 They, like many other viruses, are able to create a lytic, but also latent infection cycle.

00:38 So, infection with any of the herpesviruses means that you have it for life.

00:43 In some part or some reservoir in the human body or the human immune system, there will be one of the herpesviruses living in a latent situation.

00:54 The treatment for when one is ready to treat the herpesviruses are these drugs here: acyclovir, penciclovir, famciclovir, valacyclovir, ganciclovir, and valganciclovir.

01:07 Each of these might have efficacy against all other herpesviruses.

01:13 But of these, acyclovir and ganciclovir are the most commonly used primarily to treat herpes 1 and 2 and then cytomegalovirus.

01:24 So, let's now look at the different types of herpesviruses and we start with herpes simplex 1 or herpesvirus 1.

01:32 This is the herpes that we all know and love, or not, as it is the source of oral herpes, those cold sores which recur, which everybody is quite familiar with.

01:41 But herpes I also can cause an adult or even child onset encephalitis called sporadic encephalitis, which affects the lobar, or the temporal lobar part of the brain and is quite devastating.

01:56 One can also have a much more mild disease with conjunctivitis, and importantly, herpes simplex type 1 and herpes simplex type 2 can both cross- contaminate and cause each other's illness.

02:09 So, via self-inoculation, and I'll leave it to your imagination for how that might occur, one can get herpes 2 mostly in the genital region, up to the eyes, up to the mouth.

02:21 Herpes simplex type 2 or herpes type 2 is primarily the cause of anything related to genital herpes.

02:29 This means that babies born to mothers with genital herpes will be exposed to and can develop infection with herpes as well causing neonatal herpes disease.

02:40 Both adults and infants can develop herpes type 2 meningitis, which behaves like a very simple or benign aseptic meningitis, but they also can develop herpes type 2 encephalitis, which again, is a far more serious disease.

02:57 And once again, herpes simplex virus type 1 from the face region can transmit down via self-inoculation to the genital region.

03:07 Herpes type 3 is named varicella-zoster virus, VZV, or sometimes just varicella virus.

03:15 This is the cause of shingles and chicken pox.

03:19 Herpesvirus 4 is named Epstein-Barr virus.

03:23 Most often you'll hear us say EBV, and this is the lovely cause of infectious mononucleosis, which many adults and adolescents have experienced, but it also can be the cause of some malignant diseases.

03:38 Hairy oral leukoplakia, which can be pre-malignant, Burkitt's lymphoma, and also nasopharyngeal carcinoma.

03:46 Herpesvirus 5 is named cytomegalovirus, CMV, and this is the cause of another milder form of infectious mononucleosis in adults or children, but even more importantly, is a significant cause of congenital infection.

04:03 Mothers who are infected primarily with CMV during their pregnancy can transmit symptomatic congenital CMV to their infants.

04:12 And those infants can have hepatitis, pneumonitis, encephalitis, retinitis, you name it.

04:19 Herpesviruses 6 and 7 are the roseoloviruses, and these both can cause exanthema subitum, which is the lovely Latin name, which to us is the disease, roseola, a very common childhood illness, and we'll show pictures of this coming up very shortly.

04:36 There's a whole list of other possibilities that can be caused by these viruses, but especially human herpesvirus 7 an cause pityriasis rosea, seizures, hepatitis, hypersensitivity syndrome, encephalopathy, the whole 9 yards.

04:52 It's quite rare, but when it happens, it's quite significant.

04:55 And then finally, herpesvirus 8 is named Kaposi's sarcoma-associated herpesvirus, or many times just Kaposi's virus.

05:05 And this is, of course, by its name, the cause of Kaposi's sarcoma.