Neel K. Krishna, Ph.D.


Associate Professor

Department of Microbiology and Molecular Cell Biology

Lewis Hall, Room 3184
700 W. Olney Road
Norfolk, Virginia 23508
Office: (757) 446- 5677
Lab: (757) 446- 5645



Biomedical Graduate Students

Introduction to the Research Literature
Biomedical Sciences Seminar (Journal Club)
Concepts in Research Design Research Techniques
Advanced Molecular and Cellular Techniques, Course Director
Current Topics in Molecular Biology
Animal Virology
Advanced Cell Biology
Advanced Proteomics
Biomedical Sciences Program Track: Molecular Integrative Biosciences (MIB)

Medical Students

Medical Microbiology and Immunology, Course Director

Medical Masters Students

Medical Masters Library Thesis Research Paper


  • PhD, Pennsylvania State University School of Medicine, Hershey, PA
  • Postdoctoral Fellow, The Scripps Research Institute, La Jolla, CA

Academic Positions

2011 – Present

  • Associate Professor
  • Eastern Virginia Medical School
  • Department of Microbiology & Molecular Cell Biology
  • Department of Pediatrics

2003 – 2011

  • Assistant Professor
  • Eastern Virginia Medical School
  • Department of Microbiology & Molecular Cell Biology
  • Department of Pediatrics

Lab Members


Julia A. Sharp, Ph.D.

Postdoctoral Fellow

Norfolk, VA

Phone: (757) 446-5645


Haree K. Pallera

Undergraduate Student

Phone: (757) 446-5645


‌Research Interests

Keywords:  astrovirus, capsid/coat protein, peptide, inhibitor, complement, classical pathway, lectin pathway, C1q, MBL, Peptide Inhibitor of Complement C1 (PIC1).

I. Mechanistic study of astrovirus peptide inhibition of the complement system

My laboratory has traditionally studied the human astroviruses (HAstVs), a family of non-enveloped, icosahedral RNA viruses that cause gastroenteritis, predominantly in infants. Eight HAstV serotypes have been identified with a worldwide distribution. While the HAstVs represent a significant public health concern, very little is known about the pathogenesis and host immune response to this virus. Our research group, along with the laboratory of our collaborator Dr. Kenji Cunnion in the Department of Pediatrics, has demonstrated that HAstV-1 virions, specifically the viral capsid protein, suppress the complement system, a fundamental component of the innate immune response against pathogens in vertebrates. This is achieved by the capsid protein binding to the first component of the complement pathway, C1q and the related molecule MBL. Binding of C1q/MBL by capsid protein inhibits complement activation and its downstream effects (e.g., inflammation, cell lysis, phagocytosis, etc.). Our laboratory has recently isolated a highly potent peptide of 15 amino acid residues derived from the astrovirus capsid protein that mediates this complement suppressing activity. This peptide is termed Peptide Inhibitor of Complement C1 (PIC1). We are interested in determining the precise mechanism whereby PIC1 inhibits complement activation. Our working hypothesis of PIC1 inhibition of C1/MBL is illustrated below. Additionally, we are analyzing the role PIC1 may play in blocking the interaction of C1q/MBL with its cell surface ligands cC1qR (calreticulin) and gC1qR and the functional consequence of this activity on immune cell signaling.

Figure 1. A working model of PIC1 inhibition of C1q/MBL activation. In serum, C1q/MBL are associated with their cognate serine proteases (C1r2C1s2/MASPs respectively, shown as yellow sphere). Under normal conditions, C1q/MBL binds to an activator (aggregated antibody or directly to certain pathogens) via the globular heads (blue spheres) activating the serine proteases which leads to downstream activation of the complement system. PIC1 binds tightly to C1q/MBL conformationally altering the interaction of C1q/MBL with its respective serine proteases, thus preventing their activation.

II. Therapeutic development of PIC1

A second area of interest for our laboratory is the development PIC1 as a therapeutic for complement-mediated disease. Whilst the human complement system represents a front-line defense against pathogens such as bacteria and viruses, its uncontrolled activation can lead to severe pathology in many different inflammatory and autoimmune disorders with an immune component such as systemic lupus erythematosis, rheumatoid arthritis, inflammatory bowel disease, ischemia-reperfusion injury (myocardial infarct, stroke), glomerulonephritis, adult respiratory distress syndrome, transplant rejection, graft versus host disease and burn injuries.

Figure 2. Complement is an extremely powerful immunological amplification cascade (avalanche) for killing infectious microbes. However, disregulated complement activity can also severely damage the host and is responsible for many inflammatory and autoimmune diseases in humans. PIC1 is a synthesized peptide designed to stop complement activation at the first step in the cascade.

Currently there are only two complement inhibitors on the market. Given the very potent inhibition of the astrovirus derived peptides on the complement system, we are currently interested in developing PIC1 into a therapeutic compound as a method for regulating aberrant complement activity. Recently published data from the Cunnion and Krishna labs demonstrates that this peptide can block ABO incompatibility in vitro (a classical pathway mediated disease) and inhibit complement activation in vivo. We are currently evaluating the efficacy of PIC1 in pre-clinical models of complement-mediated disease such as acute intravascular hemolytic transfusion reaction (ABO incompatibility) as a proof of concept for eventual therapeutic development for conditions such as hemolytic anemia of the newborn (fetal hydrops, newborn jaundice), sickle cell crisis, and generalized acute intravascular transfusion reactions.


Figure 3. PIC1 inhibits human red blood cell (RBC) lysis in vitro. Top panel: ABO incompatible destruction of RBCs by the classical pathway of complement. In this example, transfused cells expressing A antigen have been exposed to incompatible recipient serum containing anti-A IgM. The bound IgM molecule is then recognized by serum complement C1 complex (C1q + C1r2C1s2). Upon binding IgM, C1 activates the classical pathway resulting in complement deposition on the donor cell and eventual clearance or lysis of host RBCs by the membrane attack complex (MAC). For clarity, only C1 binding and MAC formation are illustrated here. We hypothesized that PIC1 would bind to C1 and inhibit classical pathway mediated destruction of the target RBCs. Bottom panel: PIC1 inhibits complement activity in vitro. Human O serum was incubated with increasing concentrations of PIC1 or a buffer control and then added to human AB erythrocytes.  PIC1 blocked complement mediated hemolysis of the RBCs in a dose dependent manner. Values are the means of three independent experiments.  Error bars represent the SEM. Adapted from Mauriello et al., 2013.

In the News

Inducted into Alpha Omega Alpha (AOA) Honor Society, May 2013

Virginia Innovation Partnership U.S. Department of Commerce iP6 Challenge grant award recipient, April 2013:

Hampton Roads Community Foundation Yearbook, 2012 article: Researchers Closer to Development of Drug to Prevent Deadly Immune Response, August 27, 2010

Original Research Articles (peer-reviewed)

Role of molecular diagnostics in the management of infectious disease emergencies.

Krishna NK, Cunnion KM.

Med Clin North Am. 2012 Nov;96(6):1067-78. doi: 10.1016/j.mcna.2012.08.005. Epub 2012 Sep 27. Review.

PMID: 23102477 [PubMed - indexed for MEDLINE]

A novel peptide inhibitor of classical and lectin complement activation including ABO incompatibility.

Mauriello CT, Pallera HK, Sharp JA, Woltmann JL Jr, Qian S, Hair PS, van der Pol P, van Kooten C, Thielens NM, Lattanzio FA, Cunnion KM, Krishna NK.

Mol Immunol. 2013 Jan;53(1-2):132-9. doi: 10.1016/j.molimm.2012.07.012. Epub 2012 Aug 18.

PMID: 22906481 [PubMed - indexed for MEDLINE]

Hyperglycemic conditions inhibit C3-mediated immunologic control of Staphylococcus aureus.

Hair PS, Echague CG, Rohn RD, Krishna NK, Nyalwidhe JO, Cunnion KM.

J Transl Med. 2012 Mar 5;10:35. doi: 10.1186/1479-5876-10-35.

PMID: 22390383 [PubMed - indexed for MEDLINE] Free PMC Article

Potent inhibition of the classical pathway of complement by a novel C1q-binding peptide derived from the human astrovirus coat protein.

Gronemus JQ, Hair PS, Crawford KB, Nyalwidhe JO, Cunnion KM, Krishna NK.

Mol Immunol. 2010 Nov-Dec;48(1-3):305-13. doi: 10.1016/j.molimm.2010.07.012. Epub 2010 Aug 21.

PMID: 20728940 [PubMed - indexed for MEDLINE]

Human astrovirus coat protein binds C1q and MBL and inhibits the classical and lectin pathways of complement activation.

Hair PS, Gronemus JQ, Crawford KB, Salvi VP, Cunnion KM, Thielens NM, Arlaud GJ, Rawal N, Krishna NK.

Mol Immunol. 2010 Jan;47(4):792-8. doi: 10.1016/j.molimm.2009.10.006. Epub 2009 Nov 6.

PMID: 19896716 [PubMed - indexed for MEDLINE]

Human astrovirus coat protein: a novel C1 inhibitor.

Krishna NK, Cunnion KM.

Adv Exp Med Biol. 2008;632:237-51. Review.

PMID: 19025126 [PubMed - indexed for MEDLINE]

Human astrovirus coat protein inhibits serum complement activation via C1, the first component of the classical pathway.

Bonaparte RS, Hair PS, Banthia D, Marshall DM, Cunnion KM, Krishna NK.

J Virol. 2008 Jan;82(2):817-27. Epub 2007 Oct 24.

PMID: 17959658 [PubMed - indexed for MEDLINE] Free PMC Article

Capsid protein synthesis from replicating RNA directs specific packaging of the genome of a multipartite, positive-strand RNA virus.

Venter PA, Krishna NK, Schneemann A.

J Virol. 2005 May;79(10):6239-48.

PMID: 15858008 [PubMed - indexed for MEDLINE] Free PMC Article

Identification of structural domains involved in astrovirus capsid biology.

Krishna NK.

Viral Immunol. 2005;18(1):17-26. Review.

PMID: 15802951 [PubMed - indexed for MEDLINE] Free PMC Article

Complex formation among murine cytomegalovirus US22 proteins encoded by genes M139, M140, and M141.

Karabekian Z, Hanson LK, Slater JS, Krishna NK, Bolin LL, Kerry JA, Campbell AE.

J Virol. 2005 Mar;79(6):3525-35.

PMID: 15731247 [PubMed - indexed for MEDLINE] Free PMC Article

Analysis of RNA packaging in wild-type and mosaic protein capsids of flock house virus using recombinant baculovirus vectors.

Krishna NK, Marshall D, Schneemann A.

Virology. 2003 Jan 5;305(1):10-24.

PMID: 12504536 [PubMed - indexed for MEDLINE]

Large-scale, pH-dependent, quaternary structure changes in an RNA virus capsid are reversible in the absence of subunit autoproteolysis.

Taylor DJ, Krishna NK, Canady MA, Schneemann A, Johnson JE.

J Virol. 2002 Oct;76(19):9972-80.

PMID: 12208973 [PubMed - indexed for MEDLINE] Free PMC Article

Virus-like particles of a fish nodavirus display a capsid subunit domain organization different from that of insect nodaviruses.

Tang L, Lin CS, Krishna NK, Yeager M, Schneemann A, Johnson JE.

J Virol. 2002 Jun;76(12):6370-5.

PMID: 12021370 [PubMed - indexed for MEDLINE] Free PMC Article

Characterization of virus-like particles assembled in a recombinant baculovirus system expressing the capsid protein of a fish nodavirus.

Lin CS, Lu MW, Tang L, Liu W, Chao CB, Lin CJ, Krishna NK, Johnson JE, Schneemann A.

Virology. 2001 Nov 10;290(1):50-8.

PMID: 11883005 [PubMed - indexed for MEDLINE]

Insertion of capsid proteins from nonenveloped viruses into the retroviral budding pathway.

Krishna NK, Wills JW.

J Virol. 2001 Jul;75(14):6527-36.

PMID: 11413320 [PubMed - indexed for MEDLINE] Free PMC Article

Formation of an RNA heterodimer upon heating of nodavirus particles.

Krishna NK, Schneemann A.

J Virol. 1999 Feb;73(2):1699-703.

PMID: 9882383 [PubMed - indexed for MEDLINE] Free PMC Article

Importance of basic residues in the nucleocapsid sequence for retrovirus Gag assembly and complementation rescue.

Bowzard JB, Bennett RP, Krishna NK, Ernst SM, Rein A, Wills JW.

J Virol. 1998 Nov;72(11):9034-44.

PMID: 9765448 [PubMed - indexed for MEDLINE] Free PMC Article

Genetic determinants of Rous sarcoma virus particle size.

Krishna NK, Campbell S, Vogt VM, Wills JW.

J Virol. 1998 Jan;72(1):564-77.

PMID: 9420260 [PubMed - indexed for MEDLINE] Free PMC Article

Altered Rous sarcoma virus Gag polyprotein processing and its effects on particle formation.

Xiang Y, Ridky TW, Krishna NK, Leis J.

J Virol. 1997 Mar;71(3):2083-91.

PMID: 9032340 [PubMed - indexed for MEDLINE] Free PMC Article

Transport and processing of the Rous sarcoma virus Gag protein in the endoplasmic reticulum.

Krishna NK, Weldon RA Jr, Wills JW.

J Virol. 1996 Mar;70(3):1570-9.

PMID: 8627676 [PubMed - indexed for MEDLINE] Free PMC Article

Differential proteolytic processing leads to multiple forms of the CA protein in avian sarcoma and leukemia viruses.


Pepinsky RB, Papayannopoulos IA, Chow EP, Krishna NK, Craven RC, Vogt VM.


J Virol. 1995 Oct;69(10):6430-8.


PMID: 7666544 [PubMed - indexed for MEDLINE] Free PMC Article


Positionally independent and exchangeable late budding functions of the Rous sarcoma virus and human immunodeficiency virus Gag proteins.


Parent LJ, Bennett RP, Craven RC, Nelle TD, Krishna NK, Bowzard JB, Wilson CB, Puffer BA, Montelaro RC, Wills JW.


J Virol. 1995 Sep;69(9):5455-60.


PMID: 7636991 [PubMed - indexed for MEDLINE] Free PMC Article


Selected Book Chapters (out of 5)

Krishna NK, Koci MD, Guix S. 2013. Chapter 5: Immune Responses. In: Astrovirus Research: Essential Ideas, Everyday Impacts, Future Directions. Ed. S. Schultz-Cherry. Springer Science+Business Media, New York.

Krishna NK and Cunnion KM. 2011. Discovery of a novel inhibitor of the classical and lectin pathways of complement and its potential as a therapeutic modulator in preventing ischemia-reperfusion damage. Curr. Trends Immunol. Vol. 12, 77-88. Review.

Patent Applications

Provisional application filed 21 July, 2010. Title: “Peptide compounds to regulate the complement system.” Inventors:  Krishna NK and Cunnion KM.

Patents Granted

United States Patent 8,241,843. Issued: August 14, 2012. Title: “Methods for regulating complement cascade proteins using astrovirus coat protein and derivatives thereof.” Inventors: Krishna NK and Cunnion KM.

United states Patent US 20080286294. Issued: November 20, 2008. Title: “Nodavirus-VLPs Immunization Composition.” Inventors: Thiery R, Baud M, Cabon J, Cozien J, Lamour F, Lin CS, Krishna NK, Johnson JE and Schneemann A.