Virus-specific IgA Antibodies Research Articles

Orally Dissolving Film as a Potential Vaccine Delivery Carrier to Prevent Influenza Virus Infection

Orally dissolving films (ODF) are designed to be dissolved on the tongue and absorbed in the mouth. It offers multiple advantages over the commonly used needle-based vaccines, especially in terms of convenience allowing safe, painless, and easy self-administration. As the efficacy of ODF-encapsulated influenza vaccines has not been demonstrated, we assessed the protection elicited by inactivated influenza virus (A/PR/8/34, PR8) vaccine delivered using ODFs in mice. Trehalose and pullulan components of the ODF ensured that the HA antigens of the inactivated PR8 virus retained their stability while ensuring the rapid release of the vaccines upon exposure to murine saliva. Mice were immunized thrice by placing the PR8-ODF on the tongues of mice at 4-week intervals, and vaccine-induced protection was evaluated upon lethal homologous challenge infection. The PR8-ODF vaccination elicited virus-specific serum IgG and IgA antibody responses, hemagglutinin inhibition (HAI), and viral neutralization. Upon challenge infection, ODF vaccination showed higher levels of IgG and IgA antibody responses in the lungs and antibody-secreting cell (ASC) responses in both lung and spleen compared to unimmunized controls. These results corresponded with the enhanced T cell and germinal center B cell responses in the lungs and spleens. Importantly, ODF vaccination significantly reduced lung virus titers and inflammatory cytokines (IFN-γ, IL-6) production compared to unvaccinated control. ODF vaccination ensured 100% survival and prevented weight loss in mice. These findings suggest that influenza vaccine delivery through ODFs could be a promising approach for oral vaccine development.

Domestic pigs are susceptible to experimental infection with non-human primate-derived Reston virus without the need for adaptation

Domestic pigs are a critical component of the food supply and one of the most commonly raised production animals. Pork consumption has driven the intensification of pig production expanding into environments conducive to increased emergence and spread of infectious diseases, including the spillover of pathogens into human populations. One of these emerging viruses, Reston virus (RESTV), is an enigma among the Orthoebolavirus genus in that its lack of human pathogenicity is in stark contrast to the high virulence associated with most other ebolaviruses. RESTV is, however, associated with outbreaks of highly lethal hemorrhagic disease in non-human primates (NHP), as well as poorly understood clinical manifestations of mixed virulence and lethality in naturally and experimentally infected domestic pigs. Our results show it is possible for RESTV derived from an NHP to infect domestic pigs resulting in a spectrum of disease, from asymptomatic to severe respiratory distress. Further, we report on the first experimental transmission of RESTV between infected pigs and a co-housed, naïve animal, as well as the first report of the successful use of group oral fluids for the detection of RESTV RNA and virus-specific IgA antibodies.

Sublingual Vaccination with Live Influenza Virus Induces Better Protection Than Oral Immunization in Mice.

Both sublingual (SL) and oral vaccine administration modalities are convenient, easy, and safe. Here, we have investigated the differences in vaccine efficacy that are induced by oral and sublingual immunization with live influenza virus (A/Hong Kong/1/1968, H3N2) in mice. Intranasally administering a lethal dose of the influenza virus resulted in the deaths of the mice, whereas viral replication in the lungs did not occur upon SL or oral administration. At 30 days post-immunization through the SL or oral route, the mice were intranasally challenge-infected with the lethal dose of the homologous influenza virus. Both SL and oral immunizations with the influenza virus elicited significantly higher levels of virus-specific IgG and IgA antibody responses, as well as HAI titers in the sera. Upon challenge infection, the SL immunization elicited higher levels of pulmonary IgG antibody and CD8+ T cell responses than the oral immunization. Enhanced splenic germinal center B (GC B) and B cell proliferation were also detected from the SL immunization, both of which were significantly greater than those of the oral immunization. Importantly, compared to oral immunization, significantly lessened lung viral loads and bodyweight reductions were observed from the SL immunization and these parameters contributed to prolonging the survival of the immunized mice. These results indicate that both SL and oral administration could be effective routes in inducing protective immunity against influenza virus infection, with SL immunization being the better of the two delivery routes.

Saliva as a useful tool for evaluating upper mucosal antibody response to influenza.

Mucosal immunity plays a crucial role in controlling upper respiratory infections, including influenza. We established a quantitative ELISA to measure the amount of influenza virus-specific salivery IgA (sIgA) and salivary IgG (sIgG) antibodies using a standard antibody broadly reactive to the influenza A virus. We then analyzed saliva and serum samples from seven individuals infected with the A(H1N1)pdm09 influenza virus during the 2019-2020 flu seasons. We detected an early (6-10 days post-infection) increase of sIgA in five of the seven samples and a later (3-5 weeks) increase of sIgG in six of the seven saliva samples. Although the conventional parenteral influenza vaccine did not induce IgA production in saliva, vaccinated individuals with a history of influenza infection had higher basal levels of sIgA than those without a history. Interestingly, we observed sIgA and sIgG in an asymptomatic individual who had close contact with two influenza cases. Both early mucosal sIgA secretion and late systemically induced sIgG in the mucosal surface may protect against virus infection. Despite the small sample size, our results indicate that the saliva test system can be useful for analyzing upper mucosal immunity in influenza.

Secretory immunoglobulin A of the respiratory system and COVID-19

The main focus in the course of COVID-19 goes on assessing the overall immune response. The role of mucosal immunity in this disease has not been studied sufficiently.The studyaimed to analyze published data about secretory IgA as a significant indicator of the mucosal immune response of the respiratory tract in the context of the COVID-19 pandemic.Methods.Articles were identified via PubMed bibliographic database. The time-span of research was two years (2020, 2021).Results.The search identified 54 articles. There is evidence that secretory IgA (sIgA) is the main antibody isotype of the mucosal immunity. It is produced in quantities significantly higher than those of all other isotypes of immunoglobulins combined. sIgA antibodies are effective against various pathogens, including the SARS-CoV-2 virus, due to mechanisms such as neutralization, suppression of adhesion to the mucosal surface and invasion of epithelial cells, agglutination and facilitating the removal of pathogenic microorganisms with the mucosal secretions. Virus-specific IgA antibodies in the blood serum are detected in patients with COVID-19 as early as two days after the first symptoms, while IgM or IgG class antibodies appear only after 5 days. We accessed the efficacy of intranasal immunization as to induction of predominant production of sIgA in the upper and lower respiratory tract.Conclusion.The current information on the local immune response of the respiratory mucosa is important for understanding the pathophysiological mechanisms of the disease, diagnosis, and development of new methods of treatment and prevention of COVID-19.

Mannose Conjugated Chitosan-based Influenza Nanovaccine Intranasal Inoculation Enhances the Cross-reactive Immunity in Maternal Antibodies Positive Pigs

Abstract Swine influenza A virus (SwIAV) causes respiratory tract infection in pigs. Parenteral administration of inactivated SwIAV vaccine in weaned piglets provides variable protection due to preexisting specific maternal derived antibodies (MDA). We developed killed SwIAV antigen (KAg) encapsulated mannose-conjugated chitosan nanoparticles (mCS NPs-KAg) vaccine which targets dendritic cells. In MDA-positive piglets, prime-boost intranasal inoculation of mCS NPs-KAg vaccine elicited enhanced homologous (H1N2-OH10), heterologous (H1N1-OH7), and heterosubtypic (H3N2-OH4) influenza virus-specific secretory IgA (sIgA) antibody response in nasal passage compared to control CS NPs-KAg vaccinates. In both mCS NPs-KAg and CS NPs-KAg vaccinates upon challenge with a heterologous virus observed augmented cross-reactive virus-specific sIgA antibody response in nasal swab, lung lysate, and bronchoalveolar lavage (BAL) fluid, and IgG antibody levels in lung lysate and BAL fluid samples. Whereas the multivalent commercial inactivated SwIAV vaccine administered intramuscular had increased only the specific serum IgG antibody response. Additionally, mCS NPs-KAg vaccine increased the specific recall lymphocyte proliferation, and the frequency of IFNγ secreting T cells, late effector and effector memory T cells, and cytokines IL-4, IL-10, and IFNγ gene expression compared to CS NPs-KAg and commercial SwIAV vaccinates. Both the mCS NPs-KAg and CS NPs-KAg vaccines efficiently cleared the challenge virus load from airways and reduced the lung lesions compared to commercial vaccine. Overall, mCS NP-KAg vaccine in MDA-positive pigs induced a robust cross-reactive immunity and offered cross-protection against influenza virus.

Immunity and Protective Efficacy of Mannose Conjugated Chitosan-Based Influenza Nanovaccine in Maternal Antibody Positive Pigs.

Parenteral administration of killed/inactivated swine influenza A virus (SwIAV) vaccine in weaned piglets provides variable levels of immunity due to the presence of preexisting virus specific maternal derived antibodies (MDA). To overcome the effect of MDA on SwIAV vaccine in piglets, we developed an intranasal deliverable killed SwIAV antigen (KAg) encapsulated chitosan nanoparticles called chitosan-based NPs encapsulating KAg (CS NPs-KAg) vaccine. Further, to target the candidate vaccine to dendritic cells and macrophages which express mannose receptor, we conjugated mannose to chitosan (mCS) and formulated KAg encapsulated mCS nanoparticles called mannosylated chitosan-based NPs encapsulating KAg (mCS NPs-KAg) vaccine. In MDA-positive piglets, prime-boost intranasal inoculation of mCS NPs-KAg vaccine elicited enhanced homologous (H1N2-OH10), heterologous (H1N1-OH7), and heterosubtypic (H3N2-OH4) influenza virus-specific secretory IgA (sIgA) antibody response in nasal passage compared to CS NPs-KAg vaccinates. In vaccinated upon challenged with a heterologous SwIAV H1N1, both mCS NPs-KAg and CS NPs-KAg vaccinates augmented H1N2-OH10, H1N1-OH7, and H3N2-OH4 virus-specific sIgA antibody responses in nasal swab, lung lysate, and bronchoalveolar lavage (BAL) fluid; and IgG antibody levels in lung lysate and BAL fluid samples. Whereas, the multivalent commercial inactivated SwIAV vaccine delivered intramuscularly increased serum IgG antibody response. In mCS NPs-KAg and CS NPs-KAg vaccinates increased H1N2-OH10 but not H1N1-OH7 and H3N2-OH4-specific serum hemagglutination inhibition titers were observed. Additionally, mCS NPs-KAg vaccine increased specific recall lymphocyte proliferation and cytokines IL-4, IL-10, and IFNγ gene expression compared to CS NPs-KAg and commercial SwIAV vaccinates in tracheobronchial lymph nodes. Consistent with the immune response both mCS NPs-KAg and CS NPs-KAg vaccinates cleared the challenge H1N1-OH7 virus load in upper and lower respiratory tract more efficiently when compared to commercial vaccine. The virus clearance was associated with reduced gross lung lesions. Overall, mCS NP-KAg vaccine intranasal immunization in MDA-positive pigs induced a robust cross-reactive immunity and offered protection against influenza virus.

Humoral immune responses and neutralizing antibodies against SARS-CoV-2; implications in pathogenesis and protective immunity

The magnitude and the quality of humoral responses against SARS-CoV-2 have been associated with clinical outcome. Although the elicitation of humoral responses against different viral proteins is rapid and occurs in most infected individuals, its magnitude is highly variable among them and positively correlates with COVID-19 disease severity. This rapid response is characterized by the almost concomitant appearance of virus-specific IgG, IgA and IgM antibodies that contain neutralizing antibodies directed against different epitopes of the Spike glycoprotein. Of particularly interest, the antibodies against domain of the Spike that interacts with the cellular receptor ACE2, known as the receptor binding domain (RBD), are present in most infected individuals and are block viral entry and infectivity. Such neutralizing antibodies protect different animal species when administered before virus exposure; therefore, its elicitation is the main target of current vaccine approaches and their clinical use as recombinant monoclonal antibodies (mAbs) is being explored. Yet, little information exists on the duration of humoral responses during natural infection. This is a key issue that will impact the management of the pandemic and determine the utility of seroconversion studies and the level of herd immunity. Certainly, several cases of reinfection have been reported, suggesting that immunity could be transient, as reported for other coronaviruses. In summary, although the kinetics of the generation of antibodies against SASR-CoV-2 and their protective activity have been clearly defined, their role in COVID-19 pathogenesis and the length of these responses are still open questions.

Influenza vaccine efficacy induced by orally administered recombinant baculoviruses.

Although vaccine delivery through the oral route remains the most convenient and safest way for mass immunization purposes, this method is limited by the requirement for large antigen doses and low vaccine efficacy. In this study, we generated recombinant baculoviruses (rBVs) expressing influenza hemagglutinin (A/PR/8/34) and orally delivered a low dose of rBVs to evaluate its vaccine efficacy in mice. Intranasal rBV vaccination was included in the whole experiment for comparison. We found that oral vaccination elicited high levels of virus-specific IgG and IgA antibody responses in both serum and mucosal samples (lung, tracheal, intestinal, fecal and vaginal). Surprisingly, complete protection from the lethal influenza challenge was observed, as indicated by reductions in the virus titer, inflammatory cytokine production, body weight change, and enhanced survival. These results suggest that oral delivery of the influenza rBV vaccine induces mucosal and systemic immunity, which protect mice from the lethal influenza virus challenge. Oral delivery of baculovirus vaccines can be developed as an effective vaccination route.

Efficacy of orally administered porcine epidemic diarrhea vaccine-loaded hydroxypropyl methylcellulose phthalate microspheres and RANKL-secreting L. lactis

Here, we examined the efficacy of are combinant subunit antigen-based oral vaccine for preventing porcine epidemic diarrhea virus (PEDV). First, we generated a soluble recombinant partial spike S1 protein (aP2) from PEDV in E. coli and then evaluated the utility of aP2 subunit vaccine-loaded hydroxypropyl methylcellulose phthalate microspheres (HPMCP) and RANKL-secreting L. lactis (LLRANKL) as a candidate oral vaccine in pregnant sows. Pregnant sows were vaccinated twice (with a 2 week interval between doses) at 4 weeks before farrowing. Titers of virus-specific IgA antibodies in colostrum, and neutralizing antibodies in serum, of sows vaccinated with HPMCP (aP2) plus LL RANKL increased significantly at 4 weeks post-first vaccination. Furthermore, the survival rate of newborn suckling piglets delivered by sows vaccinated with HPMCP (aP2) plus LL RANKL was similar to that of piglets delivered by sows vaccinated with a commercial killed porcine epidemic diarrhea virus (PED) vaccine. The South Korean government promotes a PED vaccine program (live-killed-killed) to increase the titers of IgA and IgG antibodies in pregnant sows and prevent PEDV. The oral vaccine strategy described herein, which is based on a safe and efficient recombinant subunit antigen, is an alternative PED vaccination strategy that could replace the traditional strategy, which relies on attenuated live oral vaccines or artificial infection with virulent PEDV.

CpG ODN G9.1 as a novel nasal ODN adjuvant elicits complete protection from influenza virus infection without causing inflammatory immune responses

This study examined the protective efficacy of and immune response to a nasal influenza vaccine combined with a novel mucosal oligodeoxynucleotide (ODN) adjuvant, CpG ODN G9.1 (G9.1), in a model of infection limited to the upper respiratory tract (URT) and a model of infection in the lower respiratory tract (LRT). Mice were nasally primed with an A/California/7/2009 (Cal7) split vaccine (X179A) plus G9.1 and were then nasally given a booster with X179A alone. When mice were challenged with either a large (infection of the LRT) or small (infection limited to the URT) volume of live Cal7 influenza virus, mice nasally given G9.1 combined with X179A had a markedly higher rate of protection against infection limited to the URT. Moreover, this group of mice promptly recovered from an infection of the LRT. When mice were subcutaneously (s.c.) given X179A as a current form of vaccination, they had no protection from an infection limited to the URT but they did recover from an infection of the LRT. The patterns of protection were closely correlated with influenza virus-specific mucosal secretory IgA (SIgA) or serum IgG antibody (Ab) responses. Thus, SIgA Abs responses play an important role in protection from an infection limited to the URT while influenza virus-specific serum IgG Ab responses help to protect from an infection of the LRT. A finding of note is that lungs from mice nasally given G9.1 had low levels of type I IFN-associated protein- and transcription factor-specific mRNA expression. These results suggest that nasal G9.1 can be used as an effective and safe mucosal adjuvant for influenza vaccines since this nasal vaccine system elicits both mucosal SIgA and serum IgG Ab responses that provide complete protection without inducing potent inflammatory responses.

Influenza M2 virus-like particle vaccination enhances protection in combination with avian influenza HA VLPs.

Despite the ability to induce a broad range of cross protection, M2e5x virus-like particles (VLPs) alone provide limited vaccine efficacy and confer low efficacy of protection against highly pathogenic avian influenza virus (HPAIV) infection in chickens. Avian influenza hemagglutinin (HA) has been a major antigenic target that enhances humoral immunity, but the efficacy of avian HA-based vaccines against HPAIV needs to be further improved. In this study, we evaluated the vaccine efficacy induced by combination of conserved tandem repeat M2e5x VLPs and HA VLPs against an avian influenza virus. We found that combinatorial vaccine elicited higher levels of reassortant H5N1 (rgH5N1) virus-specific IgG, IgG1, IgG2a and IgA antibody responses compared to M2e5x VLPs in sera and lungs of mice. Combinatorial VLPs vaccination induced higher levels of CD8+ T cell and germinal center B cell responses in lung and spleen compared to M2e5x VLPs. Combinatorial VLPs vaccination showed significantly reduced inflammatory responses and lung viral loads upon rgH5N1 virus challenge infection, resulting in less body weight loss compared to M2e5x VLPs alone. These results indicate that immune responses to both M2e and HA might provide a strategy of vaccination inducing enhanced protection against avian influenza virus.

Comparative studies of mucosal humoral and cellular immune responses to2009 pandemic H1N1 influenza virus in mice.

The nasal-associated lymphoid tissues (NALTs), embedded in the submucosa of murine upper respiratory tract, represents an important site of induction for local mucosal immune responses to airborne pathogens and intranasal vaccines. Here, we systematically investigated the mucosal humoral and cellular immune responses of NALTs in mice infected with A/Beijing/501/2009 (BJ501) and A/Puerto Rico/8/1934 (PR8) viruses. Compared with PR8 infection, BJ501 induced a more rapid increase of virus-specific IgA and IgG antibodies in the nasal lavage fluid and a higher ratio of IgG1/IgG2a, indicating a stronger Th2 response to BJ501 in mucosal immunity. In addition, using virus-specific enzyme-linked immunospot assay (ELISpot assay), we observed higher and earlier responses of virus-specific IgA and IgG antibody-secreting cells (ASCs) and IFN-γ and IL-4 cytokine-secreting cells (CSCs) in NALTs of mice intranasally infected with BJ501 virus. In particular, the frequency of BJ501-specific IFN-γ-CSCs significantly correlated with the kinetics of BJ501 virus load in NALTs, suggesting an important role of IFN-γ-CSCs-associated mucosal cellular immune responses in BJ501 virus clearance. Collectively, BJ501 induced a more comprehensive and rapid mucosal immune responses in NALTs of mice, providing further understanding of the immune responses elicited by 2009 pandemic H1N1 virus in upper respiratory tract. Keywords: nasal-associated lymphoid tissues (NALTs); influenza virus; mucosal immune response; Th1/Th2 response.

IgA polymerization contributes to efficient virus neutralization on human upper respiratory mucosa after intranasal inactivated influenza vaccine administration

ABSTRACTUnlike the current injectable influenza vaccines, intranasally administered influenza vaccines induce influenza virus-specific IgA antibodies in the local respiratory mucosa as well as IgG antibodies in the systemic circulation. Our previous study showed that after five volunteers underwent intranasal administration with inactivated H3N2 or H5N1 vaccines, their IgA antibodies on the upper respiratory tract were present as monomers, dimers, and multimers (trimers and tetramers). Moreover, the multimers associated with the highest virus neutralizing activity. However, it has remained elusive whether a more practical intranasal vaccination strategy could induce the high-performance IgA multimers in the nasal mucosa. In the present study, volunteers were administered with two doses of the intranasal trivalent whole-virus inactivated influenza vaccine and showed that in nasal wash samples the amount of multimeric IgA correlated positively with virus neutralizing titers, indicating that the multimeric IgA antibodies play an important role in the antiviral activity at the nasal mucosa. Surface plasmon resonance analysis of the binding dynamics of nasal wash derived IgA monomers, dimers, and multimers against recombinant trimeric influenza virus HA showed that sample fractions containing IgA multimers dissociated from HA less well than sample fractions without IgA multimers. Thus, IgA multimers may “stick” to the antigen more tightly than the other structures. In summary, intranasal administration of two doses of multivalent inactivated influenza vaccines induced multimeric IgA. Multimerization of mucosal IgA antibodies conferred higher neutralizing activity against viruses in the nasal mucosa, possibly by increasing their cohesion to virus antigens.

Evaluation of seasonal influenza vaccines for H1N1pdm09 and type B viruses based on a replication-incompetent PB2-KO virus

Vaccination is the first line of protection against influenza virus infection in humans. Although inactivated and live-attenuated vaccines are available, each vaccine has drawbacks in terms of immunogenicity and safety. To overcome these issues, our group has developed a replication-incompetent PB2-knockout (PB2-KO) influenza virus that replicates only in PB2-expressing cells. Here we generated PB2-KO viruses possessing the hemagglutinin (HA) and neuraminidase (NA) segments from H1N1pdm09 or type B viruses and tested their vaccine potential. The two PB2-KO viruses propagated efficiently in PB2-expressing cells, and expressed chimeric HA as expected. Virus-specific IgG and IgA antibodies were detected in mice immunized with the viruses, and the immunized mice showed milder clinical signs and/or lower virus replication levels in the respiratory tract upon virus challenge. Our results indicate that these PB2-KO viruses have potential as vaccine candidates.

Mucosal immunization and adjuvants.

The goal of the influenza vaccine is to prevent influenza virus infection and control the yearly seasonal epidemic and pandemic. However, the presently available parenteral influenza vaccine induces only systemic humoral immunity, which does not prevent influenza virus infection on the mucosal surface. Secretary IgA antibodies play an important role in preventing natural infection. Moreover, the IgA antibody response mediates cross-protection against variant viruses in animal models. Thus, a mucosal influenza vaccine that induces mucosal immunity would be a powerful tool to protect individuals from the influenza virus. Although the function of the mucosal immune system, especially in the respiratory tract, is not completely understood, there are several studies underway to develop mucosal influenza vaccines. Here, we will review current knowledge concerning the induction of IgA, the role of B-cell production of influenza virus specific IgA antibodies in anti-influenza immunity, and the role of humoral memory responses induced upon vaccination.

MyD88 Signaling Is Indispensable for Primary Influenza A Virus Infection but Dispensable for Secondary Infection

Recent studies have revealed that innate immunity is involved in the development of adaptive immune responses; however, its role in protection is not clear. In order to elucidate the exact role of Toll-like receptor (TLR) or RIG-I-like receptor (RLR) signaling on immunogenicity and protective efficacy against influenza A virus infection (A/PR/8/34 [PR8]; H1N1), we adapted several innate signal-deficient mice (e.g., TRIF(-/-), MyD88(-/-), MyD88(-/-) TRIF(-/-), TLR3(-/-) TLR7(-/-), and IPS-1(-/-)). In this study, we found that MyD88 signaling was required for recruitment of CD11b(+) granulocytes, production of early inflammatory cytokines, optimal proliferation of CD4 T cells, and production of Th1 cytokines by T cells. However, PR8 virus-specific IgG and IgA antibody levels in both systemic and mucosal compartments were normal in TLR- and RLR-deficient mice. To further assess the susceptibility of these mice to influenza virus infection, protective efficacy was determined after primary or secondary lethal challenge. We found that MyD88(-/-) and MyD88(-/-) TRIF(-/-) mice were more susceptible to primary influenza virus infection than the B6 mice but were fully protected against homologous (H1N1) and heterosubtypic (H5N2) secondary infection when primed with a nonlethal dose of PR8 virus. Taken together, these results show that MyD88 signaling plays an important role for resisting primary influenza virus infection but is dispensable for protection against a secondary lethal challenge.

Local immune response to respiratory syncytial virus infection is diminished in senescence-accelerated mice

The effect of ageing on the local defence system against respiratory syncytial virus (RSV) infection was investigated using an aged mouse model of the senescence-accelerated mouse (SAM) strain P1. Following intranasal infection with RSV, SAM-P1 mice showed a marked loss in weight, with elevated virus growth in the lungs and prolonged virus shedding. The increased susceptibility to RSV infection was associated mainly with diminished cellular immunity by local virus-specific cytotoxic T lymphocytes and natural killer cells. The deficiency in cellular immune responses was due to a lack of clonal expansion of CD4(+) and CD8(+) T lymphocytes, together with an imbalance of T-helper type 1 (Th1)/Th2 cytokine production in the respiratory tract, including the lungs. Furthermore, the production of virus-specific local IgA antibody was restrained. Prolonged virus loading in the lungs of SAM-P1 mice caused a massive infiltration of CD16(+)/32(+) inflammatory cells, which was one factor responsible for severe pneumonia. The adoptive transfer of immune-competent spleen cells achieved an appreciable protection for SAM-P1 mice against RSV challenge infection. These results suggested that age-related immune dysfunction, especially defects in cellular immune responses, accounts for the increased morbidity and mortality in RSV infection of the elderly.

Detection of FMD virus type specific IgG1, IgG2 and IgA antibodies in milk and serum of buffaloes vaccinated with oil adjuvanted polyvalent FMD vaccine

The present investigation was carried out on 15 randomly selected milch buffaloes divided into three groups on the basis of lactation at an organized farm, to study the foot and mouth disease virus type specific antibodies in milk and serum following FMD vaccination. Milk and serum samples collected before vaccination i.e. 0 day and on 7, 14, 28, 42 and 56 days post vaccination, were analyzed for the detection of FMD virus specific IgG1, IgG2 and IgA antibody response by indirect double antibody sandwich ELISA.Significant FMD virus type specific antibody titres (IgG1, IgG2 and IgA) were detected in milk and serum of buffaloes on different days post vaccination, though the levels of antibodies were lower in milk as compared to serum. FMD virus type specific IgG1 was found to be the predominant subclass as compared to IgG2 and IgA both in milk and serum of vaccinated buffaloes. Milk and serum IgG1, IgG2 and IgA antibody titres were positively correlated with values of regression coefficient (R) as 0.506, 0.434 and 0.396, respectively.

Ginseng and Salviae herbs play a role as immune activators and modulate immune responses during influenza virus infection

We have investigated the adjuvant roles of common herbal medicines (ginseng, Salviae) and their effects on early immune responses during influenza virus infection in a mouse model. Intranasal co-administration with inactivated influenza virus A (PR8) and ginseng or Salviae extract increased the levels of influenza virus specific antibodies and neutralizing activities compared to immunization with PR8 alone, and provided protective immunity. Salviae co-administration significantly enhanced IFN-γ and IL-2 cytokine producing splenocytes while ginseng induced high levels of IL-4 and IL-5 cytokine producing cells after challenge infection. Cells expressing an early activation marker CD69 and levels of a pro-inflammatory cytokine IL-6 were highly elevated in lungs from naïve mice during challenge virus infection, which might be a mechanism in lung inflammation leading to death. In contrast, immunized mice that were co-administered ginseng or Salviae modulated CD69 expressing immune cells, did not produce IL-6, and showed significant enhancement of influenza virus specific IgA antibody in lungs after challenge virus infection. Therefore, these results indicate that both ginseng and Salviae play a role as mucosal adjuvants against influenza virus as well as immuno-modulators during influenza virus infection.