Resistance primer

Open the interactive resistance explorer →

How genotypes are scored here

Each mutation adds a penalty score for each drug; some combinations add more. The total maps to a level, modelled on the Stanford HIVdb approach:

1	Susceptible	score < 10
2	Potential low-level resistance	10–14
3	Low-level resistance	15–29
4	Intermediate resistance	30–59
5	High-level resistance	≥ 60

A drug's contribution to the genotypic susceptibility score (GSS) is 1 (levels 1–2), 0.75 (3), 0.5 (4) or 0 (5). After virological failure, aim for at least two fully active drugs, or a fully active high-barrier anchor (dolutegravir or boosted darunavir).

The table is abridged and approximate, for teaching. Use the laboratory report or Stanford HIVdb clinically.

Signature mutations

M184V	Selected by lamivudine/emtricitabine; reduces viral fitness and increases tenofovir and zidovudine susceptibility.
M184I	Usually precedes M184V; same phenotype.
K65R	Selected by tenofovir (and abacavir); reduces tenofovir/abacavir/3TC activity but increases zidovudine susceptibility.
K103N	The classic efavirenz/nevirapine mutation; rilpivirine, doravirine and etravirine stay active.
E138K	Rilpivirine signature mutation, often with M184I.
Y181C	Broad first-generation NNRTI resistance; reduces rilpivirine and etravirine.
Y188L	High-level resistance to doravirine, efavirenz and rilpivirine.
Q148H	Integrase pathway; with G140S it reduces dolutegravir/bictegravir and abolishes raltegravir.
N155H	Raltegravir/elvitegravir pathway; second-generation INSTIs largely retained alone.
R263K	Selected by dolutegravir in INSTI-naive patients; low-to-intermediate dolutegravir resistance.
G118R	Rare dolutegravir-selected mutation with broad INSTI resistance.
I50L	Atazanavir signature mutation; increases susceptibility to other PIs.
I84V	Broad PI mutation; contributes to darunavir resistance with others.
L76V	Darunavir resistance-associated mutation.

Reverse transcriptase (RT)

Mutation	Abacavir	Zidovudine	Emtricitabine	Lamivudine	Tenofovir disoproxil	Doravirine	Efavirenz	Etravirine	Rilpivirine
M41L	5	15			5
K65R	45	-10	30	30	50
K65N	30		15	15	30
D67N	5	15			5
T69ins	60	60	30	30	60
K70R	5	30			5
K70E	15		10	10	30
L74V	30
L74I	30
Y115F	30				10
Q151M	60	60	10	10	15
M184V	15	-10	60	60	-10
M184I	15	-10	60	60	-10
L210W	5	30			5
T215Y	10	60			10
T215F	10	60			10
K219Q	5	15
K219E	5	15
A98G						10	15	10	15
L100I						15	60	30	60
K101E						15	30	30	45
K101P						15	60	60	60
K103N							60
K103S							45
V106A						45	30
V106M						30	60
V108I						10	10
E138A								10	15
E138G								10	15
E138K						10	10	15	45
E138Q								10	15
V179D						10	10	10	10
Y181C						10	30	30	45
Y181I						15	30	60	60
Y181V						15	30	60	60
Y188L						60	60	10	60
Y188H						15	30		15
G190A						10	45	10	15
G190S						15	60	10	15
G190E						60	60	45	60
H221Y							10		15
P225H						10	45
F227C						60	15	30	30
F227L						15
M230L						30	45	30	60
Y318F						30

Combination penalties

M41L + T215Y/T215F → ABC +5, AZT +15, TDF +5
M41L + L210W + T215Y/T215F → ABC +10, AZT +10, TDF +10
D67N + K70R + K219Q/K219E → ABC +5, AZT +10, TDF +5

Integrase (IN)

Mutation	Bictegravir	Cabotegravir	Dolutegravir	Raltegravir
T66I		10		15
T66K	15	15	15	30
E92Q	10	10	10	30
T97A		10	5	10
G118R	30	45	30	60
E138A	10	10	10	15
E138K	10	10	10	15
E138T	10	10	10	15
G140A	10	10	10	15
G140C	10	10	10	15
G140S	10	10	10	15
Y143C		10		45
Y143H		10		45
Y143R		10		60
Q148H	15	30	15	60
Q148K	30	45	30	60
Q148R	25	45	25	60
N155H	10	15	10	60
R263K	30	30	30	15

Combination penalties

G140S/G140A/G140C + Q148H/Q148K/Q148R → BIC +30, CAB +40, DTG +30
E138K/E138A/E138T + Q148H/Q148K/Q148R → BIC +25, CAB +35, DTG +25
N155H + Q148H/Q148K/Q148R → BIC +20, CAB +20, DTG +20

Protease (PR)

Mutation	Atazanavir	Darunavir
V32I	15	15
L33F	5	5
M46I	10
M46L	10
I47V	10	15
G48V	30
I50L	60
I50V		20
I54L	15	20
I54M	15	20
L76V		20
V82A	15
V82F	10	10
I84V	60	15
N88S	60
L90M	20