Outcome Of Superinfection Research Articles

TIV Vaccination Modulates Host Responses to Influenza Virus Infection that Correlate with Protection against Bacterial Superinfection.

Background: Influenza virus infection predisposes to secondary bacterial pneumonia. Currently licensed influenza vaccines aim at the induction of neutralizing antibodies and are less effective if the induction of neutralizing antibodies is low and/or the influenza virus changes its antigenic surface. We investigated the effect of suboptimal vaccination on the outcome of post-influenza bacterial superinfection. Methods: We established a mouse vaccination model that allows control of disease severity after influenza virus infection despite inefficient induction of virus-neutralizing antibody titers by vaccination. We investigated the effect of vaccination on virus-induced host immune responses and on the outcome of superinfection with Staphylococcus aureus. Results: Vaccination with trivalent inactivated virus vaccine (TIV) reduced morbidity after influenza A virus infection but did not prevent virus replication completely. Despite the poor induction of influenza-specific antibodies, TIV protected from mortality after bacterial superinfection. Vaccination limited loss of alveolar macrophages and reduced levels of infiltrating pulmonary monocytes after influenza virus infection. Interestingly, TIV vaccination resulted in enhanced levels of eosinophils after influenza virus infection and recruitment of neutrophils in both lungs and mediastinal lymph nodes after bacterial superinfection. Conclusion: These observations highlight the importance of disease modulation by influenza vaccination, even when suboptimal, and suggest that influenza vaccination is still beneficial to protect during bacterial superinfection in the absence of complete virus neutralization.

Infection kinetics and antibody responses in Deccani sheep during experimental infection and superinfection with bluetongue virus serotypes 4 and 16.

Aim:The current study was designed to understand the infection kinetics and antibody responses of major circulating serotypes of bluetongue virus (BTV) in India, i.e., BTV-4 and BTV-16 through experimental infection and superinfection of Deccani sheep, a popular breed of sheep found in the southern states of India.Materials and Methods:Experimental infection with 106 TCID50/ml BTV-4 was followed by superinfection with BTV-16 and vice versa. Along with observing for clinical signs and immunological responses in the experimentally infected sheep, the effect of infection of one specific serotype on the outcome of superinfection with a different serotype was also studied.Results:Certain interesting findings have been made in the course of experimental infection, such as prominent signs of infection in BTV-4 infection, mild or no clinical signs in BTV-16-infected and superinfected animals, and non-seroconversion of one of the BTV-16-superinfected animals. In addition, BTV was isolated from infected sheep in all the experimental conditions except BTV-16 superinfection. Furthermore, it was observed that immune response in the form of type-specific antibodies was slower with BTV-16 superinfection.Conclusion:Superinfection of a sheep with more than one serotype of BTV is a common phenomenon in BT endemic countries like India. Such situation was replicated in an experimental infection in the current study, and the findings to our knowledge are first of a kind and are likely to aid in unfolding the newer aspects of BTV pathogenesis and virulence.

HIV-1 elite controllers: Beware of super-infections

Super- and co-infection with HIV-1 are generally associated with accelerated disease progression. We report on the outcome of super-infection in two HIV-1 infected individuals previously known as elite controllers. Both presented an acute retroviral syndrome following super-infection and showed an immuno–virological progression thereafter. Host genotyping failed to reveal any of the currently recognized protective factors associated with slow disease progression. This report indicates that elite controllers should be informed of the risk of super-infection, and illustrates the complexity of mounting broad anti-HIV immunity.

Kinetics of WHV-HDV replication in acute fatal course of woodchuck hepatitis

The objective of this study was to evaluate, by developing one-step real-time PCR, the outcome of superinfection with hepatitis D virus (HDV) genotype I in woodchucks that were chronic carriers of woodchuck hepatitis virus (WHV) and did not show relevant signs of liver damage. Three woodchucks (Marmota monax) chronically infected with WHV were superinfected with a woodchuck HDV inoculum. The evolution of the WHV and HDV infections was monitored by quantifying HDV-RNA, WHV-DNA, and HDV-WHV antigens and antibodies. WHV and HDV sequencing was also performed and liver markers were evaluated. Liver damage was assessed using the Ishak method. All woodchucks showed a high HDV viral load, antigenemia and short survival after superinfection. Histopathological examination of autoptic liver samples showed massive liver necrosis compatible with an acute fatal course of hepatitis. The WHV sequencing showed that the virus population was not substituted by the WHV inoculum. The HDV sequencing performed during superinfection and at autopsy indicated amino acid changes in immune dominant regions of the HDV antigen. The strong correlation between acute infection with HDV genotype I and rapid and fatal liver failure indicates that HDV can be an important factor in the prognosis of HDV-WHV-superinfected woodchucks.

O.009 HDV-WHV genotypes and outcome of superinfection in woodchuck model

O.009 HDV-WHV genotypes and outcome of superinfection in woodchuck model