Infectivity and duration of drug-resistant virus

Some strains of resistant virus have been found to be less infectious. One study has suggested that resistant virus has only a 25% capacity to infect others compared to wild-type virus.1 However, a consensus appears to have emerged, based on a significant body of research, that resistance mutations acquired at the time of infection may persist for many years in the absence of treatment.

This is different than what occurs in patients who develop drug resistance mutations during treatment. If these patients stop taking antiretroviral therapy, the bulk of the viral population reverts to the fittest strain of HIV in their body, the wild-type strain (although resistant virus is likely to persist in 'archived' DNA). However, in patients initially infected with a resistant strain, there is no wild-type strain archived in the body to become dominant, and random reversion of the virus to wild-type is very rare.

A British study of 14 people infected with a drug-resistant strain found that the vast majority of drug-resistant viruses persisted over two to 36 months.2 Multidrug resistance in two of these cases was found to be stable for over 18 months.

Resistant virus, including acquired multidrug resistance, has been found to persist nearly unchanged after periods up to seven years in one small, six-patient study.3 4 5 6 7

A large American study found resistance mutations in 12% of a treatment-naive cohort after eight years of infection.8

The M184V mutation has been seen to revert to wild type, with a viral load increase sometimes associated with that reversion.9 3 4 10


  1. Leigh-Brown AJ et al. Transmission fitness of drug-resistant human immunodeficiency virus and the prevalence of resistance in the antiretroviral-treated population. J Infect Dis 187: 683-686, 2003
  2. Pao D et al. Long-term persistence of primary genotypic resistance after HIV-1 seroconversion. J Acquir Immune Defic Syndr 37, 2004
  3. Brenner BG et al. Persistence and fitness of multidrug resistant human immunodeficiency virus type 1 acquired in primary infection. J Virol 76: 1753-1761, 2002
  4. Brenner B et al. Persistence of multidrug-resistant HIV-1 in primary infection leading to superinfection. AIDS 18: 1653-1660, 2004
  5. Barbour JD et al. Persistence of primary drug resistance among recently HIV-1 infected adults. AIDS 18: 1683-1689, 2004
  6. Delaugerre C et al. Persistence of HIV-1 multidrug resistance without any antiretroviral treatment 2 years after sexual transmission. Antivir Ther 8: S201, 2003
  7. Ravaux I et al. Persistence in HIV-1 protease of resistance mutations in absence of drug selective pressure three years after sexual transmission of a multiclass drug resistant variant. Antivir Ther 8: S415, 2003
  8. Novak RM et al. Prevalence of antiretroviral drug resistance mutations in chronically HIV-infected, treatment-naive patients: implications for routine resistance screening before initiation of antiretroviral therapy. Clin Infect Dis 40: 468-474, 2005
  9. Brenner B et al. Resistance to antiretroviral drugs in patients with primary HIV-1 infection. Investigators of the Quebec Primary Infection Study. Int J Antimicrob Agents 16: 429-434, 2000
  10. Little S et al. Persistence of transmitted drug-resistant virus among subjects with primary HIV infection deferring antiretroviral therapy. Eleventh Conference on Retroviruses and Opportunistic Infections, San Francisco, abstract 36LB, 2004
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.