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INTRODUCTION

Most of the viruses in this chapter cause skin lesions as their primary clinical manifestation. As described in Table 37–1, herpes simplex viruses (HSV) 1 and 2 and varicella-zoster virus cause vesicles. Human herpesvirus-6 causes roseola infantum characterized by a pink macular or maculopapular rash on the trunk. Human herpesvirus 8 causes Kaposi’s sarcoma (KS) characterized by purple macular or nodular lesions.

Table 37–1Features of Skin Lesions of Herpesviruses, Poxviruses, and Human Papillomavirus

Smallpox virus causes pustules, but the virus has been eradicated, so these lesions are not seen in medical practice today. Molluscum contagiosum virus (MCV), a member of the poxvirus family, causes fleshy papules on the skin. Human papillomavirus (HPV) causes papillomas (warts) on skin and mucous membranes of organs such as the cervix and larynx. Of the viruses described in this chapter, only two of the herpesviruses, cytomegalovirus and Epstein–Barr virus, do not cause skin lesions.

All of the viruses in this chapter have DNA as their genome (Table 37–2). The herpesviruses and poxviruses have linear double-stranded DNA, whereas HPV has circular double-stranded DNA. Herpesviruses and HPV replicate in the nucleus of infected cells, whereas poxviruses replicate in the cytoplasm.

Table 37–2Properties of Herpesviruses, Poxviruses, and Human Papillomavirus

Additional information regarding the clinical aspects of infections caused by the viruses in this chapter is provided in Part IX entitled Infectious Diseases beginning on page 607.

HERPESVIRUSES

OVERVIEW

The herpesvirus family contains seven important human pathogens: HSV types 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein–Barr virus, human herpesvirus 6 (HHV-6), and human herpesvirus 8 (also known as Kaposi’s sarcoma–associated herpesvirus [KSHV]).

All herpesviruses are structurally similar. Each has an icosahedral core surrounded by a lipoprotein envelope (Figure 37–1). The genome is linear double-stranded DNA. The virion does not contain a polymerase. They are large (120–200 nm in diameter), second in size only to poxviruses.

Figure 37–1

Herpes ...

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