CD4 and infection: Here we observed a statistically significant difference between the CD4+ T-cell counts, and viral load of patients followed in Portugal and infected by virus of the MA1 compared to subtype B. Given that the two groups were normalised for factors known to influence CD4+ T-cell counts and viral load, these results suggest that the infection by MA1 viruses may lead to a lower viral load and a slower decrease of the CD4+ T-cell count when compared with infections by a virus of the predominant subtype.