<s>[INST] context: ANTIVIRAL DRUGS: CLASSI FICATION 1.Anti-Herpes virus Idoxuridine, Acyclovir, Valacyclovir, Famciclovir, Ganciclovir*, Foscarnet* 2 Anti-Retrovirus (a) Nucleoside reverse transcriptase inhibitors (Nis): Zidovudine (AZT), Didanosine, Zalcitabine*, Stavudine, Lamivudine, Abaca vir (b) Nonnucleoside reverse transcriptase inhibitors (NNis): Nevirapine, Eirenz, Delavirdine* (c) Protease inhibitors: Ritonavir, Indinavir, Nelfinavir, Saquinavir, Amprenavir*, Lopinavir 3. Anti-Influenza virus Amantadine, Rimantadine* 4. NonselectiVe antiviral drugs Ribavirin, Lamivudine, Adefovir dipivoxil, Interferon a * Not yet marketed in India. Acyclovir This deoxiguanosine analogue antiviral drug requires a virus specific enzyme for conversion to the active metabolite that inhibits DNA synthesis and viral replication. Acyclovir is active only against herpes group of viruses; H. simplex type I is most sensitive followed by H. simplex type II > varicella-zoster virus= Epstein-Barr virus; while cytomegalovirus (CMV) is practically not affected. Both H. simplex and varicella-zoster virus have been found to develop resistance to acyclovir during therapy; the former primarily due to mutants deficient in thymidine kinase activity and the latter primarily by change in specificity of virus directed enzyme so that its affinity for acyclovir is decreased. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:767,768 [/INST] question: Acyclovir is indicated in: | options: A: Candida B: Herpes simplex C: Mycoplasma D: Pneumocystis | answer: B </s>