Neither the number of HIV-1 proviruses within individual infected cells in HIV-1–infected patients nor their genetic relatedness within individual infected cells and between cells and plasma virus are well defined. To address these issues we developed a technique to quantify and genetically characterize HIV-1 DNA from single infected cells in vivo. Analysis of peripheral blood CD4 + T cells from nine patients revealed that the majority of infected cells contain only one copy of HIV-1 DNA, implying a limited potential for recombination in virus produced by these cells. The genetic similarity between HIV populations in CD4 + T cells and plasma implies ongoing exchange between these compartments both early and late after infection.

Extended-spectrum β-lactamase (ESBL) -producing Enterobacteriaceae have been notifiable according to the Swedish Communicable Disease Act since 2007. A major increase in the number of cases has been observed, with 2099 cases in 2007 and 7225 cases in 2012. The majority of the isolates are Escherichia coli. Additionally, Swedish data on the prevalence of ESBL-producing invasive isolates of E. coli are available through EARS-Net, and through biannual point prevalence studies, where molecular characterization of isolates from the entire country is carried out. This paper describes major trends in the Swedish epidemiology of ESBL-producing E. coli in the period 2007-2012. Isolates from the point prevalence studies were subjected to antimicrobial susceptibility testing, ESBL genotyping, pulsed-field gel electrophoresis, multi-locus sequence typing and phylogenetic grouping with PCR. The distribution of sequence types, resistance genes and susceptibility levels were all stable over the three study periods. The dominating resistance gene conferring ESBL was blaCTX -M-15 , found in 54-58% of the isolates. ST131 represented 34-38% of the isolates. Other major sequence types were ST38, ST69, ST405, ST617 and ST648, each representing 2-6% of the isolates. Phylogenetic group B2 was the most common, and was observed in 41-47% of the isolates. However, among ST131 isolates the B2 phylogenetic group represented 90-98% of the isolates. The most important epidemiological difference seen over time was that the median age of infected women decreased from 62 to 52 years (p <0.0001) and infected men from 67 to 64 years. A potential explanation might be the shift towards a higher proportion of community-acquired infections in individuals lacking comorbidities.

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The live attenuated SIVmacC8 vaccine was able to induce long-term protection against heterologous intrarectal SIVsm challenge in a proportion of macaques but not against the more divergent HIV-2, which was given intravenously.

The efficacy of a recombinant human immunodeficiency virus (HIV) type 2 canarypox (ALVAC HIV-2) vaccine candidate given alone or in combination with HIV-2 envelope gp125 or HIV-2 V3 synthetic peptides was investigated in 14 cynomolgus monkeys. High antibody titers to HIV-2 gp125 were demonstrated in monkeys given booster immunizations with gp125. Neutralizing antibody titers were low (< or = 20) in all monkeys except 2. Significant lymphocyte proliferative responses to killed HIV-2 virions were observed in monkeys given booster immunizations with gp125. HIV-2-specific cytotoxic T lymphocytes were demonstrated prior to viral challenge in 3 of 12 monkeys. After challenge with homologous cell-free HIV-2 propagated in monkey cells, 4 of 10 monkeys immunized with ALVAC HIV-2 plus HIV-2 gp125 or V3 peptides were protected, as determined by negative virus isolation and polymerase chain reaction for viral DNA. Four monkeys immunized with ALVAC HIV-2 alone were not protected. All 12 control monkeys became infected. There was no correlation between the immunologic parameters studied and protection against infection in the vaccinated monkeys.

In a monkey model we used a chimeric SIV expressing the HIV-1 envelope gene (SHIV-4) as a live attenuated vaccine and a virulent SIVsm as a mucosal challenge. Four cynomolgus monkeys were inoculated intravenously with SHIV-4. Virus was repeatedly isolated from blood mononuclear cells of all four animals for 2 to 7 months after the inoculation of SHIV. All monkeys developed neutralizing antibodies to HIV-1 and high antibody titers to HIV-1 envelope glycoproteins. In contrast, no neutralizing antibodies to SIVsm were detected and cross-reacting antibodies to SIV envelope glycoproteins were demonstrable in low titers. Nine to 12 months after the SHIV inoculation the four monkeys and six naive control monkeys were challenged intrarectally with 10 monkey infectious doses of macaque cell-grown SIVsm. After a follow-up period of 1 year, two of four SHIV-infected monkeys were completely protected against SIVsm infection as shown by repeated negative virus isolations and negative polymerase chain reaction for SIV envelope DNA. One naive monkey that received blood from the two protected monkeys showed no signs of infection. The remaining two SHIV-infected monkeys showed an initial infection on challenge with SIVsm, but viral replication was thereafter suppressed. Cytotoxic T lymphocytes to SIV Nef and RT were demonstrable in one of four SHIV-infected monkeys before SIVsm challenge, but this monkey was not protected against SIV infection. All six control animals yielded virus repeatedly after SIVsm challenge and three of them showed declining CD4 cell counts. Thus, infection with SHIV expressing HIV-1 envelope could induce cross-protection against mucosal SIVsm challenge.

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Improved hygiene measures in healthcare settings likely caused the sustained nationwide decrease in infection rates.