Rapid development of broadly influenza neutralizing antibodies through redundant mutations.

The neutralizing antibody response to influenza virus is dominated by antibodies that bind to the globular head of haemagglutinin, which undergoes a continuous antigenic drift, necessitating the re-formulation of influenza vaccines on an annual basis. Recently, several laboratories have described a new class of rare influenza-neutralizing antibodies that target a conserved site in the haemagglutinin stem. Most of these antibodies use the heavy-chain variable region VH1-69 gene, and structural data demonstrate that they bind to the haemagglutinin stem through conserved heavy-chain complementarity determining region (HCDR) residues. However, the VH1-69 antibodies are highly mutated and are produced by some but not all individuals, suggesting that several somatic mutations may be required for their development. To address this, here we characterize 197 anti-stem antibodies from a single donor, reconstruct the developmental pathways of several VH1-69 clones and identify two key elements that are required for the initial development of most VH1-69 antibodies: a polymorphic germline-encoded phenylalanine at position 54 and a conserved tyrosine at position 98 in HCDR3. Strikingly, in most cases a single proline to alanine mutation at position 52a in HCDR2 is sufficient to confer high affinity binding to the selecting H1 antigen, consistent with rapid affinity maturation. Surprisingly, additional favourable mutations continue to accumulate, increasing the breadth of reactivity and making both the initial mutations and phenylalanine at position 54 functionally redundant. These results define VH1-69 allele polymorphism, rearrangement of the VDJ gene segments and single somatic mutations as the three requirements for generating broadly neutralizing VH1-69 antibodies and reveal an unexpected redundancy in the affinity maturation process.

Risk of type 2 diabetes among HIV-infected and healthy subjects in Italy.

Type 2 diabetes mellitus is a growing problem in HIV population and a comparison with the general population may help screening and prevention. In this cross-sectional study the authors determined the prevalence of type 2 diabetes mellitus in 4,249 HIV-infected subjects attending the San Raffaele Infectious Diseases Department compared with 9,148 healthy controls recruited in 15 Italian regions, and identified risk factors associated with of type 2 diabetes mellitus. Type 2 diabetes mellitus was defined as reported diabetes, a fasting plasma glucose concentration ≥7.0 mmol/l, or current use of anti-diabetic medication. Prevalence of type 2 diabetes mellitus was higher in HIV-infected than healthy subjects (4.1 vs. 2.5 %; P < 0.0001). At multivariable analysis, HIV-infected subjects (odds ratio 1.70, 95 % CI, 1.12-2.51; P = 0.009), older age (P < 0.0001), higher BMI (P < 0.0001) and hypertension (P = 0.039) were associated with a higher risk of diabetes. Among HIV-infected patients, the risk of type 2 diabetes mellitus increased with older age (P < 0.0001), higher BMI (P = 0.003), higher triglycerides (P = 0.015) lower total cholesterol (P = 0.008), longer duration of HIV infection (P = 0.036) lower nadir CD4 (P = 0.027). Prevalence of type 2 diabetes mellitus in HIV-infected subjects was almost two-fold increased than healthy subjects and it was associated with the typical risk factors of the general population and also to longer duration of HIV infection and lower nadir CD4.

[Cardiovascular disease prevention: results from Programma FASEN - H San Raffaele]. / La prevenzione delle malattie cardiovascolari: l'esperienza del Programma FASEN - H San Raffaele.

We studied 9145 workers allocated among Italian country employed in the same factory. Most of them were male, mean age 47,6 (20,2

Induction of protective antibody response by MF59-adjuvanted 2009 pandemic A/H1N1v influenza vaccine in HIV-1-infected individuals.

OBJECTIVE: to determine the immunogenicity of the monovalent vaccine against 2009 pandemic influenza A/H1N1 in HIV-1-infected individuals. DESIGN: a total of 192 participants, including 44 HIV-1-positive individuals and 148 HIV-1-negative healthy controls were enrolled to receive a single dose of MF59-adjuvanted 2009 A/H1N1v vaccine formulated to contain 7.5 microg of haemagglutin antigen. METHODS: standard haemagglutination inhibition (HAI) assay was performed to evaluate seroconversion and seroprotecsion rates against the pandemic virus in serum samples collected at baseline (T0) and 3-5-week postvaccination (T28). Seroconversion to vaccination was defined by either prevaccination HAI titer less than 1: 10 with a postvaccination titer higher than 1: 40, or a prevaccination titer higher than 1: 10 and increase of at least four-fold or more after vaccination. Seroprotection was defined by HAI titers higher than 1: 40. RESULTS: the vaccine induced specific antibody titers in HIV-1-positive individuals similar to those of HIV-1-negative controls [215.3, 95% confidence interval (CI) 150.4-308.1 vs. 275.9, 95% CI 232.6-327.3] with postvaccination seroprotection rates higher than 97%. In contrast, the seroconversion rate was lower in the HIV-1-positive individuals as compared with the HIV-1-negative controls (36.4 vs. 79.0%, P < 0.0001), likely as a consequence of their high HAI baseline titers. Multivariable logistic regression analysis showed that seroconversion was less likely in HIV-1-positive individuals [odds ratio (OR) = 0.237, 95% CI 0.104-0.539, P = 0.0006) and with increasing age (OR = 0.805, 95% CI 0.684-0.947, P = 0.009). CONCLUSIONS: a single dose of MF59-adjuvanted 2009 influenza H1N1 vaccine induced an immune response against pandemic H1N1 virus in HIV-1-positive individuals reaching titers similar to those of HIV-1-negative individuals. The seroconversion rate was negatively associated with HIV infection and increasing age.