Jan 31, 2012
Stalk-specific pH1N1 antibodies may have snuffed out seasonal H1N1 flu
Infection with 2009 H1N1 pandemic influenza (pH1N1) boosted antibodies specific to the hemagglutinin (HA) stalk rather than its head, a phenomenon that may have contributed to the disappearance of seasonal H1N1 influenza strains circulating at the time, US researchers reported in a study in Proceedings of the National Academy of Sciences. The team created chimeric hemagglutinin (cHA) proteins and viruses expressing those chimeric proteins that allowed them to detect stalk-specific antibodies in preparations that also included head-specific antibodies. (The HA of flu viruses is shaped like a mushroom, with a head and a stalk.) They found relatively high titers of stalk-specific immunoglobulin G antibodies in the blood of pH1N1-infected patients compared with those who weren't infected. By using cHA engineered with heads of viruses not seen in humans, the researchers showed the antibodies were reacting with the stalk and not the head. They also showed that the antibodies reduced virus replication. They write, "We believe that the sudden boost in antistalk titer that occurred with pH1N1 virus infection may have generated herd immunity against the seasonal virus, ultimately resulting in its disappearance."
Jan 30 Proc Natl Acad Sci abstract
Inovio reports positive antigen response to H3N2, flu B vaccines in animals
Inovio Pharmaceuticals of Blue Bell, Pa., announced today that its synthetic vaccines for influenza A H3N2 and influenza B achieved protective antibody responses in immunized animals against multiple unmatched strains. The company had previously reported that its H5N1 synthetic vaccine achieved HA inhibition titers against six unmatched H5N1 strains in a phase I study in people. "We have in animals provided protection against all of the circulating influenza strains of the last 10 years," said Inovio's President and CEO, J. Joseph Kim, PhD. "We expect additional H5N1 human data by the end of the first quarter and look forward to human data from our combined H5N1 + H1N1 vaccine in the second quarter of 2012. We expect that data from these studies, coupled with this positive data for H3N2 and Type B, will enable us to launch a clinical study of a comprehensive universal influenza vaccine in 2013."
Jan 31 Inovio press release
Study: Nosocomial norovirus outbreaks more often tied to symptomatic illness
Dutch researchers found that symptomatic patients were much more likely to spread hospital-associated norovirus infection than were asymptomatic carriers, according to a study yesterday in Clinical Infectious Diseases. Investigators analyzed data from 37 norovirus-infected patients, 9 of whom were asymptomatic, and 48 infected healthcare workers (HCWs), 37 of whom were asymptomatic. They then estimated the onset of infection on the basis of shedding kinetics. Their Monte Carlo analysis yielded a reproduction number of 0.85 (95% confidence interval [CI], 0.55-1.05) for asymptomatic patients and HCWs and 1.64 (95% CI, 1.56-1.70) for symptomatic patients and HCWs. They also found that asymptomatic HCWs were rarely involved in nosocomial outbreaks.
Jan 30 Clin Infect Dis abstract
Pakistan aims to vaccinate 33 million kids against polio
Pakistan has launched its first polio vaccination drive of the year with a 3-day campaign aimed at vaccinating 33.4 million children, the Associated Press of Pakistan (APP) reported yesterday. The effort involves 76,587 trained door-to-door vaccination teams and 9,723 teams at vaccination sites. "All of us should take the responsibility to play our due role to ensure every child is vaccinated during the upcoming campaign and no single child misses the vaccination," said Altaf Bosan, MD, the country's head of polio eradication.
Jan 30 APP report