Abstract

Hundreds of billions of dollars have been spent for over three decades in the search for an effective human immunodeficiency virus (HIV) vaccine with no success. There are also at least two other sexually transmitted viruses, for which no vaccine is available, the herpes simplex virus (HSV) and the hepatitis C virus (HCV). Traditional textbook explanatory paradigm of rapid mutation of retroviruses cannot adequately address the unavailability of vaccine for many sexually transmissible viruses, since HSV and HCV are DNA and non-retroviral RNA viruses, respectively, whereas effective vaccine for the horsefly-transmitted retroviral cousin of HIV, equine infectious anemia virus (EIAV), was found in 1973. We reported earlier the highly disordered nature of proteins in outer shells of the HIV, HCV, and HSV. Such levels of disorder are completely absent among the classical viruses, such as smallpox, rabies, yellow fever, and polio viruses, for which efficient vaccines were discovered. This review analyzes the physiology and shell disorder of the various related and non-related viruses to argue that EIAV and the classical viruses need harder shells to survive during harsher conditions of non-sexual transmissions, thus making them vulnerable to antibody detection and neutralization. In contrast, the outer shell of the HIV-1 (with its preferential sexual transmission) is highly disordered, thereby allowing large scale motions of its surface glycoproteins and making it difficult for antibodies to bind to them. The theoretical underpinning of this concept is retrospectively traced to a classical 1920s experiment by the legendary scientist, Oswald Avery. This concept of viral shapeshifting has implications for improved treatment of cancer and infections via immune evasion.

Highlights

  • Biomolecules 2019, 9, 178 to this, a closer look at all available data reveals that such an explanation is limited as there are several counterexamples for this hypothesis. If this would be the case for all retroviruses that utilize the error-prone reverse transcription as the definition of retrovirus entails, why effective vaccines have been found for human immunodeficiency virus (HIV)’s horse cousin, equine infectious anemia virus (EIAV), at least since 1973? [6,7,8,9,10]

  • Using advanced computational techniques (e.g., PONDR® -VLXT) we showed that depending on a strain, the percentage of intrinsic disorder (PID) in HIV-1 matrix protein (p17) can be as high as 70%, the levels, which are very rare in the outer shells of other viruses [11,12]

  • herpes simplex virus (HSV)-2 is usually spread via sexual intercourse, whereas HSV-1 can be spread by kissing, even though the two viruses are closely related [42]

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Summary

The Mystery of the Elusive HIV Vaccine

The search for an effective human immunodeficiency virus (HIV) vaccine has spanned over 30 years with hundreds of billions of dollars spent with no success [1]. Biomolecules 2019, 9, 178 to this, a closer look at all available data reveals that such an explanation is limited as there are several counterexamples for this hypothesis. If this would be the case for all retroviruses that utilize the error-prone reverse transcription as the definition of retrovirus entails, why effective vaccines have been found for HIV’s horse cousin, equine infectious anemia virus (EIAV), at least since 1973? Using advanced computational techniques (e.g., PONDR® -VLXT) we showed that depending on a strain, the percentage of intrinsic disorder (PID) in HIV-1 matrix protein (p17) can be as high as 70%, the levels, which are very rare in the outer shells of other viruses [11,12]. With the availability of information for a wide variety of viruses that include polio, rabies, HCV, HSV, and yellow fever viruses (YFV) [3,11,12,17,18,19,20,21,22,23,24,25,26] important comparisons become feasible as we shall see below

Protein Intrinsic Disorder
Viral Shells
Virus Selection
Protein Intrinsic Disorder of Viral Shells
Outer Shell Hardness and the Classical Vaccine Successes
Influenza Virus
Viral Shapeshifters of Another Kind
HIV-1 and HIV-2
HCV and HIV
More than One Mode of Evasion
Experimental and Empirical Evidence Has Trickled in During the Last 10 Years
Findings
Implications and Potential Applications of the Viral Shapeshifters

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