Limits...
Protection of mice against lethal challenge with 2009 H1N1 influenza A virus by 1918-like and classical swine H1N1 based vaccines.

Manicassamy B, Medina RA, Hai R, Tsibane T, Stertz S, Nistal-Villán E, Palese P, Basler CF, García-Sastre A - PLoS Pathog. (2010)

Bottom Line: The recent 2009 pandemic H1N1 virus infection in humans has resulted in nearly 5,000 deaths worldwide.Passive immunization with cross-reactive monoclonal antibodies (mAbs) raised against either 1918 or A/California/04/2009 HA proteins offered full protection from death.This data provides a mechanistic basis for the protection seen in the older population, and emphasizes a rationale for including vaccination of the younger, naïve population.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America.

ABSTRACT
The recent 2009 pandemic H1N1 virus infection in humans has resulted in nearly 5,000 deaths worldwide. Early epidemiological findings indicated a low level of infection in the older population (>65 years) with the pandemic virus, and a greater susceptibility in people younger than 35 years of age, a phenomenon correlated with the presence of cross-reactive immunity in the older population. It is unclear what virus(es) might be responsible for this apparent cross-protection against the 2009 pandemic H1N1 virus. We describe a mouse lethal challenge model for the 2009 pandemic H1N1 strain, used together with a panel of inactivated H1N1 virus vaccines and hemagglutinin (HA) monoclonal antibodies to dissect the possible humoral antigenic determinants of pre-existing immunity against this virus in the human population. By hemagglutinination inhibition (HI) assays and vaccination/challenge studies, we demonstrate that the 2009 pandemic H1N1 virus is antigenically similar to human H1N1 viruses that circulated from 1918-1943 and to classical swine H1N1 viruses. Antibodies elicited against 1918-like or classical swine H1N1 vaccines completely protect C57B/6 mice from lethal challenge with the influenza A/Netherlands/602/2009 virus isolate. In contrast, contemporary H1N1 vaccines afforded only partial protection. Passive immunization with cross-reactive monoclonal antibodies (mAbs) raised against either 1918 or A/California/04/2009 HA proteins offered full protection from death. Analysis of mAb antibody escape mutants, generated by selection of 2009 H1N1 virus with these mAbs, indicate that antigenic site Sa is one of the conserved cross-protective epitopes. Our findings in mice agree with serological data showing high prevalence of 2009 H1N1 cross-reactive antibodies only in the older population, indicating that prior infection with 1918-like viruses or vaccination against the 1976 swine H1N1 virus in the USA are likely to provide protection against the 2009 pandemic H1N1 virus. This data provides a mechanistic basis for the protection seen in the older population, and emphasizes a rationale for including vaccination of the younger, naïve population. Our results also support the notion that pigs can act as an animal reservoir where influenza virus HAs become antigenically frozen for long periods of time, facilitating the generation of human pandemic viruses.

Show MeSH

Related in: MedlinePlus

Prior infection with Cal/09 virus cross-protects mice against the lethal challenge with Neth/09 isolate.(A, B) Determination of LD50 for the Neth/09 isolate in C57B/6 mice (n = 5/group). Mice were infected with the indicated doses of virus and their body weight (A) and survival (B) were monitored for 14 days. (C, D) Re-challenge of Cal/09 infected mice with Neth/09 (n = 4/group). Six weeks old C57B/6 mice were inoculated with PBS (Mock) or Cal/09 isolate (103 or 5×104 pfu). After 21 days the mice were challenged with 1×106 pfu of Neth/09 isolate. The body weight (C) and survival (D) were monitored for 14 days as in Fig. 1.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2813279&req=5

ppat-1000745-g002: Prior infection with Cal/09 virus cross-protects mice against the lethal challenge with Neth/09 isolate.(A, B) Determination of LD50 for the Neth/09 isolate in C57B/6 mice (n = 5/group). Mice were infected with the indicated doses of virus and their body weight (A) and survival (B) were monitored for 14 days. (C, D) Re-challenge of Cal/09 infected mice with Neth/09 (n = 4/group). Six weeks old C57B/6 mice were inoculated with PBS (Mock) or Cal/09 isolate (103 or 5×104 pfu). After 21 days the mice were challenged with 1×106 pfu of Neth/09 isolate. The body weight (C) and survival (D) were monitored for 14 days as in Fig. 1.

Mentions: To further evaluate the pathogenesis of Neth/09, we next determined the LD50 of Neth/09 isolate in mice. Nine-week old female C57B/6 mice were infected with different doses of virus (5×102, 5×103, 5×104, 5×105 or 5×106 pfu) and monitored for weight loss and survival over a period of 14 days p.i. (Fig. 2A and B). All mice inoculated with 5×104 pfu or higher succumbed to infection or reached the experimental end point between days 4–8 p.i. (Fig. 2A). Mice inoculated with 5×103 pfu showed a 12.2% decrease in body weight, and mice infected with 5×102 pfu showed no significant drop in weight (Fig. 2B). The LD50 for Neth/09 was determined to be 1.58×104 pfu for 9-week-old C57B/6 mice (Reed and Muench method, [33]). Overall, these data indicates that the Neth/09 isolate is more pathogenic in mice than Cal/09 and thus, in the challenge experiments described herein, the Neth/09 isolate and C57B/6 mice were used as a lethal model for 2009 pandemic H1N1.


Protection of mice against lethal challenge with 2009 H1N1 influenza A virus by 1918-like and classical swine H1N1 based vaccines.

Manicassamy B, Medina RA, Hai R, Tsibane T, Stertz S, Nistal-Villán E, Palese P, Basler CF, García-Sastre A - PLoS Pathog. (2010)

Prior infection with Cal/09 virus cross-protects mice against the lethal challenge with Neth/09 isolate.(A, B) Determination of LD50 for the Neth/09 isolate in C57B/6 mice (n = 5/group). Mice were infected with the indicated doses of virus and their body weight (A) and survival (B) were monitored for 14 days. (C, D) Re-challenge of Cal/09 infected mice with Neth/09 (n = 4/group). Six weeks old C57B/6 mice were inoculated with PBS (Mock) or Cal/09 isolate (103 or 5×104 pfu). After 21 days the mice were challenged with 1×106 pfu of Neth/09 isolate. The body weight (C) and survival (D) were monitored for 14 days as in Fig. 1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2813279&req=5

ppat-1000745-g002: Prior infection with Cal/09 virus cross-protects mice against the lethal challenge with Neth/09 isolate.(A, B) Determination of LD50 for the Neth/09 isolate in C57B/6 mice (n = 5/group). Mice were infected with the indicated doses of virus and their body weight (A) and survival (B) were monitored for 14 days. (C, D) Re-challenge of Cal/09 infected mice with Neth/09 (n = 4/group). Six weeks old C57B/6 mice were inoculated with PBS (Mock) or Cal/09 isolate (103 or 5×104 pfu). After 21 days the mice were challenged with 1×106 pfu of Neth/09 isolate. The body weight (C) and survival (D) were monitored for 14 days as in Fig. 1.
Mentions: To further evaluate the pathogenesis of Neth/09, we next determined the LD50 of Neth/09 isolate in mice. Nine-week old female C57B/6 mice were infected with different doses of virus (5×102, 5×103, 5×104, 5×105 or 5×106 pfu) and monitored for weight loss and survival over a period of 14 days p.i. (Fig. 2A and B). All mice inoculated with 5×104 pfu or higher succumbed to infection or reached the experimental end point between days 4–8 p.i. (Fig. 2A). Mice inoculated with 5×103 pfu showed a 12.2% decrease in body weight, and mice infected with 5×102 pfu showed no significant drop in weight (Fig. 2B). The LD50 for Neth/09 was determined to be 1.58×104 pfu for 9-week-old C57B/6 mice (Reed and Muench method, [33]). Overall, these data indicates that the Neth/09 isolate is more pathogenic in mice than Cal/09 and thus, in the challenge experiments described herein, the Neth/09 isolate and C57B/6 mice were used as a lethal model for 2009 pandemic H1N1.

Bottom Line: The recent 2009 pandemic H1N1 virus infection in humans has resulted in nearly 5,000 deaths worldwide.Passive immunization with cross-reactive monoclonal antibodies (mAbs) raised against either 1918 or A/California/04/2009 HA proteins offered full protection from death.This data provides a mechanistic basis for the protection seen in the older population, and emphasizes a rationale for including vaccination of the younger, naïve population.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America.

ABSTRACT
The recent 2009 pandemic H1N1 virus infection in humans has resulted in nearly 5,000 deaths worldwide. Early epidemiological findings indicated a low level of infection in the older population (>65 years) with the pandemic virus, and a greater susceptibility in people younger than 35 years of age, a phenomenon correlated with the presence of cross-reactive immunity in the older population. It is unclear what virus(es) might be responsible for this apparent cross-protection against the 2009 pandemic H1N1 virus. We describe a mouse lethal challenge model for the 2009 pandemic H1N1 strain, used together with a panel of inactivated H1N1 virus vaccines and hemagglutinin (HA) monoclonal antibodies to dissect the possible humoral antigenic determinants of pre-existing immunity against this virus in the human population. By hemagglutinination inhibition (HI) assays and vaccination/challenge studies, we demonstrate that the 2009 pandemic H1N1 virus is antigenically similar to human H1N1 viruses that circulated from 1918-1943 and to classical swine H1N1 viruses. Antibodies elicited against 1918-like or classical swine H1N1 vaccines completely protect C57B/6 mice from lethal challenge with the influenza A/Netherlands/602/2009 virus isolate. In contrast, contemporary H1N1 vaccines afforded only partial protection. Passive immunization with cross-reactive monoclonal antibodies (mAbs) raised against either 1918 or A/California/04/2009 HA proteins offered full protection from death. Analysis of mAb antibody escape mutants, generated by selection of 2009 H1N1 virus with these mAbs, indicate that antigenic site Sa is one of the conserved cross-protective epitopes. Our findings in mice agree with serological data showing high prevalence of 2009 H1N1 cross-reactive antibodies only in the older population, indicating that prior infection with 1918-like viruses or vaccination against the 1976 swine H1N1 virus in the USA are likely to provide protection against the 2009 pandemic H1N1 virus. This data provides a mechanistic basis for the protection seen in the older population, and emphasizes a rationale for including vaccination of the younger, naïve population. Our results also support the notion that pigs can act as an animal reservoir where influenza virus HAs become antigenically frozen for long periods of time, facilitating the generation of human pandemic viruses.

Show MeSH
Related in: MedlinePlus